Method for separating nucleated cells

Abstract

A method for effectively recovering nucleated cells from cell-containing fluid containing nucleated cells and cells to be removed by introducing cell-containing fluid into a filter and recovering the nucleated cells captured in the filter, recovering liquid dispersing element is used in combination with nucleated cells capturing elements, to constitute specific arrangement, and further a comparatively flat filter, where an effective filtering membrane area and packing thickness are in a specific ratio, is used.

Description

BACKGROUND OF THE INVENTION

[0002] (1) Field of the Invention

[0003] This invention relates to a method for separating and recovering only necessary cells from a fluid containing a mixture of various cells. The cells thus obtained can be used in providing therapy for various diseases, such as hematopoietic stem cell transplantation, and in fundamental sciences such as immunology and cell biology.

[0004] (2) Description of the Related Art

[0005] Japanese patent JP-A-54-119012 discloses a technique for recovering lymphocytes by capturing leukocytes on a filter from a body fluid such as blood containing leukocytes (granulocytes, monocytes and lymphocytes) and erythrocytes.

[0006] In the case of hematopoietic stem cell transplantation, cord blood stem cells are noted as a source of hematopoietic stem cells which does not cause any invasion to donors, and their clinical application is vigorously attempted, mainly in countries in Europe and America. Since cord blood stem cells are rarely transplanted to a patient immediately after being collected from a donor, unlike in other hematopoietic stem cell transfers, i.e., bone marrow transplantation and peripheral blood stem cell transplantation, they should be preserved for use after the collection. Such preservation is often needed, particularly in the case of unrelated setting. Before cryopreservation of cord blood, the separation of nucleated cells and the removal of erythrocytes is considered necessary in order to prevent side effects of erythrocytes lysis after thawing, and to reduce the volume during the cryopreservation. At present, cord blood is preserved after the separation, in most cases (“Peripheral Blood Stem Cell Transplantation” p. 173, NANKODO Ltd.). JP-B-8-69 discloses details of a protocol for separating cord blood by a Ficoll-Hypaque method, a centrifugation method using a liquid having an adjusted specific gravity, hereinafter referred to as “Ficoll method”. The Ficoll method, however, is disadvantageous in that it is only feasible on a laboratory level and requires very troublesome and time-consuming operations. International Publication No. WO 96/17514 discloses a bag system and method for separating erythrocytes in cord blood by agglutination and precipitation by the use of hydroxyethyl starch to obtain a concentrated nucleated cell suspension, and a cell suspension obtained by that method. This method is somewhat superior to the Ficoll method, a conventional method in that it involves fewer troublesome operations, but it also is time-consuming because two centrifugation runs are necessary.

[0007] As methods for solving the above complicated problems, JP-A-10-201470 discloses a filtering method wherein objective cells in blood are captured by a filter, followed by recovering with application of shear force by passing the high viscous recovering fluid through the filter. Further, recently, JP-A-10-137557, JP-A-11-178920, JP-A-11-206875, and JP-A-11-313887 have disclosed methods for separating cells, comprising compressing a filter packed with porous material to filter blood, releasing the compression to enlarge pore size of the filter material than that at filtering and introducing the fluid into the filter, to recover the objective cells with enhanced recovery rate.

[0008] However, there were many problems in these blood filtering methods including clogging of filter pores caused by aggregates such as fibrin clots and destructed blood cells in blood, resulting in reduced filtering rate and extended filtering time and complete clogging, which makes continuing treatment operation impossible. As countermeasures against these problems, a method is employed where filtering volume per unit area is reduced by expanding filtering area. As disclosed in the filtering method above, generally, blood is introduced into the filter at low speed to prevent low capturing ability of the objective cells in the filtering, while the recovering liquid is introduced into the filter at high speed in the recovery step, to wash out objective cells captured in the filter, by applying shear force of the recovering liquid. In the case of expanding the filtering area, and when the recovering liquid is introduced with high speed in the recovery operation, the recovering liquid flows predominantly near the area, where the recovering liquid is introduced, without spreading uniformly in the filtering area, thus suppressing increase in the recovery rate of the objective cells. Namely, there is a problem that to secure filtering speed and to obtain high recovery rate of the objective cells cannot be attained at the same time.

[0009] Further, in the above filtering methods, to improve recovery rate of the objective cells, the recovering liquid is introduced into the filter having more enlarged pore size of porous material in the recovery step than in the filtering step, and thus the objective cells captured in the filter is recovered. However, in practical applications, inner filter volume is expanded in the recovery step to maintain high recovery rate, therefore, volume of the recovering liquid introduced into the filter should be increased, thus centrifugal concentration is required to reduce to desired volume, and accompanied increase in material cost also provide a problem.

[0010] Further, in these methods, thickness of filtering material is controlled by compressing filtering material or reversely by releasing the compression, thus the pore size is changed. This causes troublesome operation with difficulty in exact control, and a problem of unstable recovery rate of the objective cells.

[0011] As explained above, in the conventional filtering methods, such technology is not known as simultaneously satisfies conflicting requirements each other, that is, to maintain flow rate in the filtering and to obtain high recovery of the objective cells, and also recovering process of the objective cells using smaller fluid volume is not known. Consequently, technology which can satisfy all of the above is required for separating and recovering the specific cells.

[0012] On the other hand, some methods for separating hematopoietic stem cells have been reported as substitutes for the Ficoll method and the erythrocyte aggutination and removal. JP-A-8-104643 discloses a method for recovering hematopoietic stem cells by capturing them on a filter permeable to erythrocytes, and then causing a liquid flow in a direction opposite to the first liquid flow direction. This method, however, merely uses Hanks' Balanced Salt Solution (HBSS) as the liquid for the recovery.

[0013] Dextran is a polysaccharide composed of glucose units as monomer units mainly by α-1,6 linkages, and has been used since early times as an agent for separating leukocytes. The separation of leukocytes by the-use of dextran, however, utilizes the effect of dextran as a hemagglutinating agent. After erythrocytes in a test tube are agglutinated and precipitated, centrifugation is carried out if necessary, and then leukocytes in the supernatant are recovered with a pipet (Shiro Miwa, Rinsho Kensa Gijutsu Zensho, Vol. 3, “Ketsueki Kensa” p. 425). Such an effect is not characteristic of only dextran, because hydroxyethyl starch and the like have the same hemagglutinating effect as that of dextran.

[0014] Next, systems for separating hematopoietic stem cells are described below. JP-A-7-184991 discloses an assembly for collecting cord blood, in particular, a filter for removing contaminants in cord blood, such as aggregates (e.g. micro-aggregates), tissue particles, bone particles, steatomas, etc., which is provided before a container for blood collection. This filter, however, is not for capturing cells which should be recovered, but for removing contaminants. Even if a material capable of capturing hematopoietic stem cells is used in the filter by chance, this reference does not describe the recovery of the captured hematopoietic stem cells at all.

[0015] JP-A-8-52206 discloses an apparatus comprising a membrane type plasma separator, as an apparatus for collecting cord blood which is used for separating hematopoietic stem cells from cord blood collected. This reference also discloses another separation method using an apparatus for density gradient separation, i.e., separation by the Ficoll method.

[0016] The present invention is intended to provide a method for separating cells which are desired to be recovered (hereinafter referred to as “cells to be recovered” or “necessary cells”) from a mixture of necessary cells and unnecessary cells (hereinafter referred to as “cells to be removed”) by a simple and rapid procedure. This procedure comprises a cell separation method which captures necessary cells by use of a capturing means such as filtering a fluid containing the cell mixture, and then recovering the captured cells with high recovery. The present invention also provides a line system obtained by embodiment of this method for practical clinical employment. The present invention also provides a recovering liquid used in said system, and a cell-containing fluid obtained by using the method.

[0017] In order to solve the problems identified in the prior art, the present inventors noted properties of a liquid for recovering cells from a cell-capturing means, and earnestly investigated these properties to conclude that when cells are recovered by using a recovering liquid having a definite viscosity, a high recovery can be attained. As a result of earnest investigation on the compositions of various recovering liquids, the present inventors found such a striking effect that, when cells are recovered by using a physiological solution containing dextran, a very high recovery can be attained. Thus, the objectives of the present invention have been accomplished.

[0018] One aspect of the present invention is to provide a separating method wherein the nucleated cells are recovered with high yield, while suppressing decrease in filtering rate caused by aggregates in blood, and the objective nucleated cells can be simply recovered using smaller fluid volume, in a recovery of nucleated cells captured in a filter, by introducing recovering liquid into the filter, after cell-containing fluid, containing nucleated cells and cells to be removed, is filtered through the filter.

[0019] The present inventers have extensively studied for solving the above problems, and found that, in a method for separating objective cells, by using recovering liquid dispersing means is used in combination with nucleated cells capturing means, to constitute specific arrangement and a comparatively flat filter, having specific ratio of effective filtering area and packing thickness, problems, that is, to maintain fluid rate in the filtration and to obtain high recovery of nucleated cells by uniform flow of the recovering liquid, can be solved at the same time, and thus completed the present invention.

SUMMARY OF THE INVENTION

[0020] One aspect of the present invention is directed to a cell separation method comprising steps of introducing a cell-containing fluid containing cells to be recovered and cells to be removed into a cell-capturing means capable of substantially capturing the cells to be recovered and substantially permitting passage therethrough of the cells to be removed. Then, the resulting fluid containing the cells to be removed is taken from the cell-capturing means, and then a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s is introduced into the cell-capturing means to recover therefrom the cells to be recovered which have been captured by the cell-capturing means.

[0021] Another aspect of the present invention is directed to a cell separation and preservation method comprising steps of introducing a cell-containing fluid containing cells to be recovered and cells to be removed, into a cell-capturing means capable of substantially capturing the cells to be recovered, and substantially permitting passage therethrough of the cells to be removed. The resulting fluid containing the cells to be removed is taken out of the cell-capturing means, and a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s is introduced into the cell-capturing means to recover therefrom the cells to be recovered which have been captured by the cell-capturing means. The recovered cells are then preserved.

[0022] Another aspect of the present invention is directed to a cell separation and preservation method comprising steps of introducing a cell-containing fluid containing cells to be recovered and cells to be removed into a cell-capturing means capable of substantially capturing the cells to be recovered, and substantially permitting passage of the cells to be removed. The resulting fluid containing the cells to be removed is taken from the cell-capturing means, and a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s is introduced into the cell-capturing means to recover therefrom the cells to be recovered which have been captured by the cell-capturing means. The recovered cells are then subjected to cryopreservation and thawing.

[0023] Still another aspect of the present invention is directed to a cell separation system comprising a cell-capturing means which is capable of substantially capturing cells to be recovered and substantially permitting passage therethrough of cells to be removed, which has at least an inlet and an outlet. A line for introducing into the cell-capturing means a cell-containing fluid containing the cells to be recovered and the cells to be removed is connected upstream to the inlet of the cell-capturing means. A line for introducing a liquid into the cell-capturing means is connected downstream to the outlet of the cell-capturing means, and a line for cell recovery from the inlet side of the cell-capturing means is connected upstream to the inlet of the cell-capturing means.

[0024] Still another aspect of the present invention is directed to a cell separation method comprising steps of introducing a cell-containing fluid containing cells to be recovered and cells to be removed into a cell-capturing means capable of substantially capturing the cells to be recovered and substantially permitting passage therethrough of the cells to be removed, through a line connected upstream to the inlet of the cell-capturing means. The resulting fluid containing the cells to be removed is taken out through the outlet of the cell-capturing means, and then a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s is introduced into the cell-capturing means through a line connected downstream to the outlet of the cell-capturing means to recover the cells to be recovered which have been captured by the cell-capturing means, through a line connected upstream to the inlet of the cell-capturing means.

[0025] That is, the present invention relates to the following inventions (1) to (7):

[0026] (1) A method for separation of nucleated cells by introducing cell-containing fluid, containing nucleated cells and cells to be removed, into a filter which substantially captures the nucleated cells but substantially passes the cells to be removed, followed by draining the cell-containing fluid to be removed, from the said filter and introducing thus recovering liquid into said filter to recover the nucleated cells which are captured on the filter, characterized in that a vessel as a filter, having at least an inlet and an outlet of the cell-containing fluid, is packed with nucleated cells capturing means and recovering liquid dispersing means, both consisting of porous materials, in the direction from the inlet side toward the exit side of the cell-containing fluid, in this order; said filter used has value of 15-120 cm, obtained from effective filtration area of said filter divided by thickness of the cell-capturing means in packing step; the nucleated cells in the filter are captured by introducing the cell-containing fluid into the filter from the inlet of the cell-containing fluid, followed by draining the fluid containing the cells to be removed from said filter, and introducing the recovering liquid from the outlet of the cell-containing fluid, to recover the nucleated cells, which are captured in said filter, from the inlet of the cell-containing fluid.

[0027] (2) The method for separating nucleated cells in accordance with (1), wherein aggregates-capturing means is further packed in the inlet side of the cell-containing fluid in said nucleated cells capturing means.

[0028] (3) The method for separating nucleated cells, according to (1) or (2), wherein said porous material is non-woven fabric.

[0029] (4) The method for separating nucleated cells, according to (3), characterized in that the nucleated cells capturing means and the recovering liquid dispersing means, both consisting of non-woven fabric are:

[0030] a) the cell-capturing means, consisting of non-woven fabric with mean fiber diameter of 1.1-3.0 μm and packing density of 0.1-0.3 g/cm3; and

[0031] b) the recovering liquid dispersing means, consisting of the non-woven fabric with mean fiber diameter of 0.5-1.5 μm and packing density of 0.1-0.3 g/cm3, respectively and

[0032] mean fiber diameter becomes smaller in the order of the nucleated cells capturing means and the recovering liquid dispersing means.

[0033] (5) The method for separating nucleated cells, according to (1) or (2), wherein said porous material has spongy structure.

[0034] (6) The method for separating nucleated cells, according to (5), characterized in that the nucleated cells capturing means and the recovering liquid dispersing means, both consisting of spongy structure, are:

[0035] a) the cell-capturing means, consisting of spongy structure having mean pore diameter in packing of 7-25 μm and void ratio in packing of 55-90%; and

[0036] b) the recovering liquid dispersing means, consisting of spongy structure having mean pore diameter in packing of 2-10 μm and void ratio in packing of 55-90%, respectively and mean pore size becomes smaller in the order of the nucleated cells capturing means and the recovering liquid dispersing means.

[0037] (7) The method for separating nucleated cells, according to (1), wherein said porous material is a combination of non-woven fabric and spongy structure.

[0038] Still another aspect of the present invention is directed to a liquid containing hematopoietic stem cells which is substantially free from erythrocytes and/or platelets and has a viscosity of not more than 500 mpa·s and not less than 5 mPa·s.

[0039] Still another aspect of the present invention is directed to a liquid containing cells to be recovered and substantially having no cells to be removed which is obtained by a cell separation method comprising steps of introducing a cell-containing fluid containing cells to be recovered and cells to be removed into a cell-capturing means capable of substantially capturing the cells to be recovered and substantially permitting passage therethrough of the cells to be removed. The resulting fluid containing the cells to be removed is taken out from the cell-capturing means, and then a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s is introduced into the cell-capturing means to recover therefrom the cells to be recovered which have been captured by the cell-capturing means.

[0040] Still another aspect of the present invention is directed to a liquid for recovering captured cells from a cell-capturing means which has a viscosity of not more than 500 mPa·s and not less than 5 mPa·s.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIG. 1 is one embodiment of the cell separation system according to the present invention.

[0042] FIG. 2 is a schematic view of a cell separation system used in Example 1.

[0043] FIG. 3 is a schematic view of a cell separation system used in Example 4.

[0044] FIG. 4 is a schematic view of a cell separation system used in Example 6.

PREFERRED EMBODIMENT OF THE INVENTION

[0045] In the present specification, the term “cells to be recovered” means cells used for some purpose after their separation and recovery. The term “cells to be removed” means cells unnecessary for the above purpose or cells which should be positively removed because they are, for example, pathogenic cells, so that contamination by them of cells to be recovered causes a problem.

[0046] The cell-containing fluid containing cells to be recovered and cells to be removed can be but is not limited to peripheral blood, bone marrow, cord blood (including not only that collected through a umbilical cord blood vessel but also that collected through a placenta blood vessel), lymph fluids, and those obtained by subjecting the above fluids to some treatment such as centrifugation, and suspensions obtained by resuspending cells extracted from any of various organs or tissues, in some liquid.

[0047] The term “nucleated cells” means cells having a nucleus therein. The nucleated cells include, for example, leukocytes, granulocytes, neutrophils, baso-phils, eosinophils, myelocytes, erythroblasts, lymphocytes, T lymphocytes, helper T lymphocytes, cytotoxic T lymphocytes, suppressor T lymphocytes, B lymphocytes, NK cells, NKT cells, monocytes, macrophages, dendritic cells, osteoclasts, osteoblasts, osteocytes, hematopoietic stem cells, fibroblasts and chondroblasts.

[0048] The term “mononuclear cell fraction containing hematopoietic stem cells” means a mononuclear cell population containing hematopoietic stem cells and/or hematopoietic progenitor cells (they are hereinafter given the general name “hematopoietic stem cells”). “Mononuclear cell” is a general term for cells having a nucleus therein, and specific examples thereof are lymphocytes (T cells, B cells and NK cells), monocytes, hematopoietic stem cells, myelocytes, blast cells, etc.

[0049] The content of hematopoietic stem cells in the mononuclear cell population is usually 0.01% to 99% and varies depending on the kind-of a starting cell population, and whether cells are treated or not. The content of hematopoietic stem cells is usually, for example, about 0.01% in peripheral blood, 0.05 to 1.0% in cord blood and 0.5 to 2% in bone marrow in the case of a normal person. In peripheral blood having a granulocyte colony-stimulating factor (G-CSF) administered, the content of hematopoietic stem cells differs markedly among individuals, and is 0.1 to several per cent. When cell separation using a monoclonal antibody, in particular, cell separation by a flow cytometry method is carried out, the content of hematopoietic stem cells reaches 99% in some cases. In any case, the term “mononuclear cell fraction containing hematopoietic stem cells” does not concretely specify the content of hemato-poietic stem cells at all.

[0050] The cells having no nucleus which are referred to in the present specification include, for example, erythrocytes and platelets.

[0051] The term “cells to be removed have a surface marker different from that of cells to be recovered” in the present specification means that the cells to be recovered and the cells to be removed are similarly nucleated cells, but are different in surface marker (the cells to be recovered and the cells to be removed belong different subgroups, respectively). For example, the cells to be recovered are helper T lymphocytes (having anti-CD4 antigen as a surface marker), and the cells to be removed are suppressor T lymphocytes (having anti-CD8 antigen as a surface marker).

[0052] When cells to be recovered are nucleated cells, and cells to be removed are cells having no nucleus, examples of their combination and examples of use thereof are as follows, but the combination and use are not limited thereto.

[0053] 1. Cells to be recovered: leukocytes, cells to be removed: erythrocytes, use: interferon preparation.

[0054] 2. Cells to be recovered: lymphocytes, cells to be removed: erythrocytes and platelets, use: adoptive-immuno therapy.

[0055] 3. Cells to be recovered: a mononuclear cell fraction containing hematopoietic stem cells, cells to be removed: erythrocytes and platelets, use: hematopoietic stem cell transplantation.

[0056] Cells to be recovered: endothelial precursor cells, cells to be removed: erythrocytes and platelets, use: therapeutic vasculogenesis

[0057] When cells to be recovered are nucleated cells, and cells to be removed are nucleated cells having a surface marker different from that of the cells to be recovered, examples of their combination and examples of use thereof are as follows, but the combination and use are not limited thereto.

[0058] 1. Cells to be recovered: CD34-positive nucleated cells, cells to be removed: CD34-negative nucleated cells, use: CD34-positive cell transplantation.

[0059] 2. Cells to be recovered: CD8-positive T lymphocytes, cells to be removed: CD8-negative T lymphocytes, use: adoptive-immuno therapy.

[0060] When cells to be recovered are nucleated cells and cells to be removed are cells having no nucleus and nucleated cells having a surface marker different from that of the cells to be recovered, examples of their combination and examples of use thereof are as follows, but the combination and use are not limited thereto.

[0061] 1. Cells to be recovered: CD34-positive nucleated cells, cells to be removed: erythrocytes, platelets and CD34-negative nucleated cells, use: CD34-positive cell transplantation.

[0062] 2. Cells to be recovered: CD8-positive T lymphocytes, cells to be removed: erythrocytes, platelets and CD8-negative T lymphocytes, use: adoptive-immuno therapy.

[0063] In the present invention, the cell-capturing means capable of capturing at least cells to be recovered and substantially permitting passage therethrough of cells to be removed, may comprise a container having a liquid inlet and a liquid outlet which is packed with a material capable of capturing the cells to be recovered and substantially permitting passage therethrough of the cells to be removed, and a molded container having a cell-capturing surface on its inner surface. In the present invention, “substantially captures the cells having nucleus” means that not lower than 60% of the cells having nucleus in the cell-containing fluid is captured in the filter. Further, in the present invention, “allows the cells to be removed to substantially pass through” means that not lower than 60% of the cells to be removed in the cell-containing fluid is passed through the filter. In the present invention, “cell-capturing means” may be called “cell separator” or “filter”. The material capable of capturing the cells to be recovered and substantially permitting passage therethrough of the cells to be removed may be any conventional cell-capturing material so long as it can selectively capture the cells to be recovered. The following materials, for example, are preferable because of their excellent moldability, sterilizability, and low cytotoxicity: synthetic polymers such as polyethylenes, polypropylenes, polystyrenes, acrylic resins, nylons, polyesters, polycarbonates, polyacrylamides, polyurethanes, etc.; natural polymers such as agarose, cellulose, cellulose acetate, chitin, chitosan, alginates, etc.; inorganic materials such as hydroxyapatite, glass, alumina, titania, etc.; and metals such as stainless steel, titanium, aluminum, etc.

[0064] These capturing materials may be used as they are, or after being subjected to surface modification necessary for selective passage or capture of cells, etc. For example, for improving the permeability to platelets, there is, for instance, the method comprising coating with a polymer having nonionic hydrophilic groups and basic nitrogen-containing functional groups which has been proposed in International Publication No. WO 87/05812. As a method for selective capture of cells, a method of immobilizing a ligand having affinity for specific cells, such as an amino acid, peptide, sugar or glycoprotein (including bio-ligands such as antibody and adhesion molecules) may be used, for example, by the haloaceamide method proposed in JP-A-2-261833.

[0065] The shape of the capturing material may be granular, a fiber mass, woven fabric, non-woven fabric, a spongy structure, a flat plate, etc. The granules, fiber mass, woven fabric, non-woven fabric and spongy structure are preferable because they have a large surface area per volume. From the viewpoint of ease of handling, porous structures such as the fiber mass, woven fabric, non-woven fabric and spongy structure are more preferable. Among them, the non-woven fabric and spongy structure are the most preferable from the viewpoint of the flowability of a cell suspension and productivity.

[0066] Porous material to be used as a filter material in the present invention is composed of a nucleated cells capturing means and a recovering liquid dispersing means, which are packed in the filter in the direction from the inlet side to the exit side for a cell-containing fluid, in this order.

[0067] The term “nucleated cells capturing means” in the present invention means filter material having functions for capturing nucleated cells in the cell-containing fluid and passing the cells to be removed. In the case that porous material, as material for capturing nucleated cells, is non-woven fabric, mean fiber diameter of 1.1-3.0 μm and packing density of 0.1-0.3 g/cm3 are preferable. Mean fiber diameter below 1.1 μm and packing density over 0.3 g/cm3 are not preferable since the nucleated cells are captured only at the vicinity of the upstream of the nucleated cells capturing means, and the fine pores in the filter are clogged in short period, filtering rate of the fluid is lowered, and further recovery rate is lowered due to reduced detaching efficiency of the nucleated cells. On the contrary, mean fiber diameter over 3.0 μm and packing density below 0.1 g/cm3 are not preferable since the nucleated cells can not be captured sufficiently which induces clogging of fine pores of the filter by the cell reached to the recovering liquid dispersing means at the downstream, to lower filtering rate of the fluid, and further the recovery rate is lowered by reduced detaching efficiency of the nucleated cells.

[0068] In the case that porous material, as the nucleated cells capturing means, has spongy structure, mean pore diameter in packing of 7-25 μm and void ratio in packing of 55-90% are preferable. Mean pore diameter below 7 μm and void ratio in packing below 55% are not preferable since the nucleated cells are captured only at the vicinity of the upstream of the nucleated cells capturing means, and the fine pores in the filter are clogged within short time, filtering rate of the fluid is lowered, and further recovery rate is lowered due to reduced detaching efficiency of the nucleated cells. On the contrary, mean pore diameter over 25 μm and void ratio in packing over 90% are not preferable since the nucleated cells can not be captured sufficiently which induces clogging of fine pores of the filter by the cell reached to the recovering liquid dispersing means at the downstream, to lower filtering rate of the fluid, and further the recovery rate is lowered by reduced detaching efficiency of the nucleated cells.

[0069] The term “recovering liquid dispersing means” in the present invention, means filter material having function for spreading uniformly the recovering fluid into the filtering part of the filter by means of resistant force of the filter material when the recovering liquid is introduced into the filter. In the case that porous material, as the nucleated cells capturing means, is non-woven fabric, mean fiber diameter of 0.5-1.5 μm and packing density of 0.1-0.3 g/cm3 are preferable. Mean fiber diameter below 0.5 μm and packing density over 0.3 g/cm3 are not preferable since detaching rate of the captured nucleated cells is decreased and the recovering rate is lowered, because resistance of the filter is increased and flow rate of the recovering liquid is lowered. On the contrary, mean fiber diameter over 1.5 μm and packing density below 0.1 g/cm3 are not preferable since recovery rate of the nucleated cells is decreased because resistance of the filter is small and the recovering liquid can not be spread uniformly.

[0070] In the case that porous recovering liquid dispersing means has spongy structure, mean pore diameter in packing of 2-10 μm and void ratio in packing of 55-90% are preferable. Mean pore diameter below 2 μm or less and void ratio in packing below 55% are not preferable since detaching rate of the captured nucleated cells is decreased and the recovering rate is lowered, because resistance of the filter is increased and flow rate of the recovering liquid is lowered. On the contrary, mean pore diameter over 10 μm and void ratio in packing over 90% are not preferable since recovery rate of the nucleated cells is decreased because resistance of the filter is small and the recovering liquid can not be spread uniformly.

[0071] In the present invention, it is especially important that cell-capturing means and recovering liquid dispersing means are used in combination, arranged in the specific direction. The above nucleated cells capturing means and the recovering liquid dispersing means should be packed in the direction from the inlet of the cell-containing fluid to the outlet of the filter, in this order. This arrangement can provide uniform flow of the recovering liquid and increased recovery efficiency of the captured cells.

[0072] In the present invention, in addition to the above two materials, the addition of the aggregates-capturing means is also preferable, and the aggregates-capturing means can be packed in the most inlet side of the cell-containing fluid in the filter.

[0073] The term “aggregates-capturing means” in the present invention is filter material to be packed in the inlet side of the cell-containing fluid in the nucleated cells capturing means, and which has function for capturing the cell aggregates such as fibrin clots, blood clots, activated platelets and destructed granulocytes in the cell-containing fluid, and function for suppressing decrease in flow rate as well as decrease in the recovery rate for the nucleated cells in filtering. In the case that the porous aggregates-capturing means is non-woven fabric, mean fiber diameter of 5-20 μm and packing density of 0.1-0.3 g/cm3 are preferable. Mean fiber diameter below 5 μm and packing density over 0.3 g/cm3 are not preferable since not only the aggregates but also nucleated cells and cells to be removed are captured and clog filter pores, which lowers flow rate of the filtration, and also lowers recovery rate due to incorporation of the nucleated cells into the aggregates. On the contrary, mean fiber diameter over 20 μm and packing density below 0.1 g/cm3 are not preferable since the aggregates can not be captured sufficiently and reached to the nucleated cells capturing means, which is set downstream in the filtration, to clog fine filter pores and lower filtering rate of the fluid, and further to lower the recovery rate due to incorporation of the nucleated cells into the aggregates.

[0074] In the case that the porous aggregates-capturing means has spongy structure, mean pore diameter in packing of 60-150 μm and void ratio in packing of 55-90% are preferable. Mean pore diameter below 60 μm and the void ratio in packing below 55% are not preferable since not only the aggregates but also nucleated cells and cells to be removed are captured and clog filter pores, which lowers flow rate of the filtration of the cell-containing fluid, and also lowers recovery rate due to incorporation of the nucleated cells into the aggregates. On the contrary, mean fiber diameter over 150 μm and void ratio over 90% are not preferable since the aggregates can not be captured sufficiently and reached to the material for capturing the nucleated cells, which is set downstream in the filtration and clog fine pores of the nucleated cells capturing means and lower filtering rate, and further to lower the recovery rate due to incorporation of the nucleated cells into the aggregates.

[0075] In the present invention, it is required to use the filter packed with the nucleated cells capturing means and the recovering liquid dispersing means, in specific direction, and at the same time, the filter should have value of 15-120 cm, which can be obtained from effective filtration area of said filter divided by thickness of the nucleated cells capturing means in the packing. This value over 120 cm is not preferable, since the effective filtering area is too large as compared with thickness of the nucleated cells capturing means, which suppresses uniform spread of the recovering liquid into the filtering area in the recovery step, resulting in lower recovery rate of the nucleated cells. While, this value below 15 cm causes low flow rate in filtering due to small effective filtering area and thick nucleated cells capturing means. Further, the above case is also not preferable, since resistance for introducing the recovering liquid into the filter is too high and flow rate of the recovering liquid is lowered, which in turn lowers recovery rate of the nucleated cells.

[0076] The term “fiber diameter” in the present specification means a value obtained by the following procedure.

[0077] Portions which are individually considered to be substantially uniform are sampled from a filter element which constitute a porous structure, and photographed at a magnification of 1,000 to 3,000 by using a scanning electron microscope and the like. The fiber diameter values are read from the photograph and averaged.

[0078] In the sampling, the effective filtration sectional area portion of the filter element is partitioned into sections 0.5 to 1 cm square, and of these sections, three or more sections, preferably five or more sections, are sampled at random. The random sampling is carried out, for example, by assigning a lot number to each of the above-mentioned sections and selecting sections in a necessary number or more by, for instance, a method using a table of random numbers. Then, three or more, preferably five or more portions of each sampled section are photographed, and the diameters of all photographed fibers are measured.

[0079] Here, the diameter of a fiber refers to the width of the fiber in a direction perpendicular to the fiber axis, and the average is calculated by dividing the sum of the diameters measured of all the fibers by the number of the fibers. However, data obtained in, for example, the following cases are omitted: the case where a plurality of fibers overlap one another and the width of any of them cannot be measured because the view of this fiber is obstructed by the other fibers; the case where a plurality of fibers form a thick fiber owing to their melting or the like; and the case where fibers widely different in diameter are present as a mixture.

[0080] The average of the fiber diameters is calculated from data obtained for 500 or more fibers, preferably 1,000 or more fibers by the method described above.

[0081] The term “pore size” in the present specification has the following meaning: a porous structure is cut perpendicularly to the direction of flow of blood, the area of each of pores dispersed in the whole section is measured, the diameter in terms of a circle of the pore is calculated from the area, the relationship between diameter and the number of pores is determined, and a diameter in terms of a circle at which the number of pores is largest is taken as the pore size.

[0082] That is, the term “pore size” used in the present specification has the following meaning: the diameter of each of pores dispersed in any section of the porous structure is converted to the diameter of a circle having the same area as that of the pore, a graph is obtained by plotting this diameter as abscissa at intervals of 0.1 μm, and plotting the number of pores in each interval (0.1 μm) as ordinate, and a diameter corresponding to the peak of the normal distribution curve obtained is taken as the pore size.

[0083] Specifically, the pore size is determined by photographing the surface of a capturing material by a scanning electron microscope, and visually measuring the diameters of 2,000 or more pores dispersed on the photographed surface, at random. Pores having a pore size large than the determined pore size are present in a smaller number, and the passage of particles with a diameter larger than the determined pore size through the capturing means is not always impossible.

[0084] When the measurement of the diameters of pores is difficult in determining the pore size of a porous structure, the pore size is determined as follows. A specimen with a certain thickness is obtained by cutting the porous structure at a distance of 0.5 mm or less from the surface of the porous structure in the direction of the thickness of the capturing means as perpendicularly as possible to the direction of flow of blood. The specimen is subjected to measurement by a mercury injection method (Pore Size 9320, Shimadzu Corp.). The amount of mercury injected is taken as 0% when no mercury has gotten into the pores of the porous structure. The amount of mercury injected is taken as 100% when mercury has gotten into all the pores of the porous structure. A pore size corresponding to an amount of mercury injected of 50% is taken as the pore size of the porous structure. In this case, the measurement is carried out in a pressure range of a mercury porosimeter of 1 to 1,000 psia.

[0085] In the case of a porous structure which is so flexible that when it is subjected to the measurement as it is, it is deformed during the measurement to make the detection of pores impossible, the above measurement is carried out by conducting a pretreatment such as fixation of the pores for preventing their deformation under pressure. The present invention includes such a porous structure.

[0086] In the present invention, “a vessel having at least an inlet and an outlet of the cell-containing fluid” is not limited as long as it has flat shape, and, for example, a vessel having shape observed in the known leukocytes reduction filter, disclosed in JP-B-02-13588 can be used. Namely, it has shape in which an inlet and an outlet of the fluid are faced each other in vertical direction to porous material, so as to sandwich the porous material, and shape facing each other in non-vertical direction, so as to sandwich the porous material. In the above two shapes, the latter is preferable from the standpoint of availability of filtering area of the filter and decrease in residual platelet count/erythrocyte count, and more preferable shape is such one wherein a distance between the inlet and the outlet of the fluid becomes maximum. Further, in these shapes, the inlet and the outlet of the recovering liquid can be set independently from the inlet and the outlet of the cell-containing fluid.

[0087] Material of the vessel preferably has water-insolubility, superior moldability and sterilization compatibility and low cytotoxicity. Further, hard materials are preferable so that, when the cell-containing fluid is introduced into the filter in filtering and the recovering liquid is introduced into the filter in recovery step, it shows substantially no expansion by pressure loading to the inside of the filter. When the vessel for the filter expands in the filtering, pore size of the porous filter materials becomes larger, which lowers capturing rate of the nucleated cells. Further, expansion of the vessel in the recovery is not preferable, since shear force for washing out the nucleated cells, captured in the filter material, is lowered as a result of reduced flow rate of the recovering liquid, and further the recovery rate is lowered due to large amount of the residual recovering liquid. Consequently, preferable materials include synthetic polymers such as polyethylenes, polypropylenes, polystyrenes, acrylic resins, nylons, polyesters, polycarbonates, polyacrylamides, polyurethanes, poly(vinyl chloride)s, etc.; inorganic materials such as hydroxyapatite, glass, alumina, titania, etc.; and metals such as stainless steel, titanium, aluminum, etc., but are not limited to these as long as they are hard materials and suitable for medical use.

[0088] In the method for separating nucleated cells of the present invention, the viscosity of the recovering liquid need not be particularly limited because the filter is packed with the recovering liquid dispersing means. More preferably, cells to be recovered which have been captured by the cell-capturing means are recovered by using a liquid with a specific viscosity (hereinafter referred to also as “recovering liquid” or “liquid for recovery”). The viscosity of this liquid is preferaby not be more than 500 mPa·s and not less than 5 mPa·s, more preferably not more than 100 mPa·s and not less than 5 mPa·s, further preferably not more than 50 mPa·s and not less than 7 mPa·s. When the viscosity is less than 5 mPa·s, the recovery is low. When the viscosity is more than 500 mPa·s, the passage of the liquid through the cell-capturing means is very difficult even if a pump is used, so that the work-efficiency is low. Moreover, a pressure increase is caused, so that leakage from a joint between tubes in a line tends to occur. Therefore, such viscosity values are not desirable. As a method for measuring the viscosity, use of a rotating viscometer is preferable because it is the simplest, and has a high precision. However, as described above the viscosity should not be necessarily limited as for the recovering liquid in the method for separating nucleated cells.

[0089] Any liquid may be used as the recovering liquid, so long as it has little undesirable influence on cells. For example, solutions of synthetic polymers such as poly(ethylene glycol)s poly(vinylpyrrolidone)s, poly(vinyl alcohol)s etc.; solutions of natural polymers such as methyl cellulose, gelatin, hydroxyethyl starch, dextran, chitin derivatives, collagen, fibronectin, albumin, globulin, etc.; solutions of organic substances such as glucose, saccharose, maltose, trehalose, sorbitol, glycerol, dimethyl sulfoxide, silicone oil, etc.; and mixtures thereof may be used. Typical example of the plasma protein is HSA (human serum albumin) and that of the serum is human AB serum. From the viewpoint of safety such as protection of infection, a sample from the autologous blood is idealistic, however there is a problem for requiring great deal of time and labor for the preparation thereof. In addition, in view of the prion infection, use of blood derived from bovine is not recommendable. As a result of investigation by the present inventors, it was found that an especially high recovery can be attained by using dextran. Therefore, employment of dextran is explained below in detail.

[0090] The dextran referred to herein is a glucose polymer in which most of the glucose units are joined by α-1,6 linkages. The dextran includes its partial hydrolysis products and its derivatives such as sulfate esters. Although the dextran is not limited in molecular weight, its average molecular weight is preferably 1,000 to 10,000,000, more preferably 5,000 to 5,000,000, most preferably 10,000 to 1,000,000, in view of solubility, availability, etc. Since the viscosity varies depending on the molecular weight, even at the same concentration, the molecular weight of the concentration is properly adjusted so that the viscosity may be not more than 500 mPa·s and not less than 5 mPa·s. A sterilized dextran 40 injection (a 10 w/v % solution of dextran with a molecular weight of about 40,000 in physiological saline), approved as a medicine, is on the market and hence can be suitably used. In order to adjust the viscosity to not more than 500 mPa·s and not less than 5 mPa·s, the dextran may be used singly, or in admixture with other substances. Examples of the substances are synthetic polymers such as poly(ethylene glycol)s, poly(vinyl-pyrrolidone)s, poly(vinyl alcohol)s, etc.; natural polymers such as methyl cellulose, gelatin, hydroxyethyl starch, dextran, chitin derivatives, collagen, fibronectin, albumin, globulin, etc.; and organic substances such as glucose, saccharose, maltose, trehalose, sorbitol, glycerol, dimethyl sulfoxide, etc. Although a mechanism by which cells can be recovered with high recovery by using dextran is not known at present, the present inventors conjecture that the dextran has a property of reducing the adhesiveness of the cells to the capturing material.

[0091] The solvent used for dissolving a solute in the preparation of the liquid having a viscosity of not more than 500 mPa·s and not less than 5 mPa·s, may be physiological saline, buffer solutions such as Dulbecco phosphate buffer solution (D-PBS), Hank's Balanced Salt Solution (HBSS) and the like, and media such as RPMI1640 and the like. If necessary, dextran, hydroxyethyl starch, albumin, globulin, glucose, saccharose, trehalose, globulin, citrate-phosphate-dextrose (CPD), acid-citrate-dextrose (ACD), EDTA, heparin, etc. may be incorporated into the liquid for supply of a nutriment, protection of cell membrane, or impartment of anticoagulating effect, etc.

[0092] The liquid with a specific viscosity according to the present invention is preferably one which can be used for cryopreservation of cells to be recovered, or preservation of the cells in a liquid state. As described above, for hematopoietic stem cell transplanation, in particular, hematopoietic stem cell transplanation using cord blood, a cell population freed of erythrocytes by a Ficoll method or the like is washed (because a Ficoll solution is toxic), and a cryoprotectant and the like are added thereto to prepare a cell suspension, followed by cryopreservation in liquid nitrogen or a freezer until needed for practical use. In the present invention, a cell suspension to be preserved can be prepared without troublesome operations after cell separation by using a liquid suitable both for the preservation, in particular, cryopreservation, as well as for recovery, by having a specific viscosity. Specific examples of the liquid for recovery which is usable for cryopreservation and as a cryoprotectant are, a nutriment, or a cell membrane protecting component, etc. Cryoprotectants are classified into two categories, 1) extracellular cryoprotectants, and 2) intracellular cryoprotectants, according to the action mechanism. In the first category, water-soluble polymers such as hydroxyethyl starch, dextran, poly(vinylpyrrolidone)s, etc. are generally used. In the second category, low-molecular weight organic compounds such as dimethyl sulfoxide, glycerol, etc. are generally used. The nutriment includes sugars such as glucose and the like, and various media for cell culture. As the cell membrane protecting component, albumin is generally used. Plasma is used in some cases as a combination of the nutriment and the cell membrane protecting component. As described above, these components are preferably used singly, or in combination in the liquid for recovery having a specific viscosity of the present invention. The components described above may be added at the time of cryopreservation after cell recovery.

[0093] There are generally two freezing methods employed, i.e., a simple method using a deep-freezer at −80° C., or a method comprising slow cooling in a program freezer and preservation in liquid nitrogen. For thawing cells subjected to cryopreservation, rapid thawing in a warm bath at 37° C. is generally carried out.

[0094] As a method for introducing the cell-containing fluid referred to in the present specification into the cell-capturing means, there may be adopted either a method of connecting a bag or bottle containing the cell-containing fluid through a tube, and then introducing the fluid, for example, by utilizing its fall, a roller pump, causing a flow of the fluid by squeezing the bag, or by a method of connecting a syringe containing the cell-containing fluid, and introducing the fluid by pushing the piston of the syringe by hand or using a device such as a syringe pump. The pushing by hand is characterized by its simplicity, and the use of the device is characterized in that the control of the flow rate of the recovering liquid in its introduction is easy. Therefore, a suitable method is selected depending on the purpose.

[0095] When the cell-containing fluid is introduced into the cell-capturing means, the cells to be recovered are captured, and the cells to be removed flow out, but a minority thereof remain in the container in some cases. Therefore, the cell-capturing means is preferably rinsed in order to rinse away the slight amount of the remaining cells to be removed. Any rinse may be used, so long as it is a physiological solution. Several examples thereof are physiological saline, buffer solutions such as Dulbecco phosphate buffer solution (D-PBS), Hank's Balanced Salt Solution (HBSS) and the like, and media such as RPMI1640 and the like. If necessary, dextran, hydroxyethyl starch, albumin, globulin, glucose, saccharose, trehalose, globulin, citrate-phosphate-dextrose (CPD), acid-citrate-dextrose (ACD), EDTA, or heparin, etc. may be added to the physiological solutions mentioned above for supply of a nutriment, protection of cell membrane, and impartment of anticoagulating effect, etc.

[0096] There are two directions for introduction of the rinse, i.e., the same direction as the direction of introduction of the cell-containing fluid, and the direction opposite thereto. Of these, the same direction is preferable. In the case of the opposite direction, the cells to be recovered which have been captured are liable to leak out owing to the rinsing. The viscosity of the rinse is preferably less than 5 mPa·s. When the viscosity is 5 mPa·s or more, the cells to be recovered which have been captured are liable to leak out.

[0097] In the present invention, as a method for introducing the liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s into the above-mentioned cell-capturing means, there may be adopted either a method of connecting a bag or bottle containing the liquid to the cell-capturing means through a tube, and introducing the liquid by utilizing its fall, a roller pump, by squeezing the bag, or by a method of connecting a syringe containing the liquid, and introducing the liquid into the cell-capturing means by pushing the piston of the syringe by hand, or by using a device such as a syringe pump. In this case, as in the direction of introduction of the liquid, there are two directions, i.e., the same direction as the direction of introduction of the cell-containing fluid, and the direction opposite thereto. Of these, the latter is usually preferable because the cell recovery is higher. The flow rate of the recovering liquid is preferably rapid because the recovery tends to be increased. The linear speed obtained by dividing the flow rate by the filtration sectional area is usually 0.5 cm/min. or more, preferably 5 cm/min. or more, and more preferably 10 cm/min. or more.

[0098] It is also possible to recover a slight amount of cells (or their constituents) remaining in the cell-capturing means, by introducing another liquid after introducing the recovering liquid. By this recovery, the collection of a sample for HLA typing, which is indispensable, for example, in hematopoietic stem cell transplantation, can be carried out simultaneously with the cell separation procedure. A slight amount of the cells (or their constituents) remaining in the cell-capturing means are used for various purposes, other than HLA typing such as investigation of ex vivo expansion of hematopoietic stem cells, genetic diagnosis, or employment in cell transplantation in combination with the cells obtained by the first recovery. A brief supplementary explanation of HLA typing is given below.

[0099] HLA typing is carried out by using DNA present in the nuclei of nucleated cells. Therefore, recovering the DNA is preferable to recovering the cells themselves because it is laborsaving. Accordingly, a liquid capable of lysing or disrupting the cells is preferably used as a recovering liquid. The liquid includes, for example, hypotonic liquids such as solutions of surfactants (e.g. sodium dodecyl sulfate, lauryl sodium sulfate and Triton X-100), distilled water, ion-exchanged water, etc. The DNA recovered by the use of such a liquid is purified by a well-known phenol chloroform method or the like and subjected to HLA typing.

[0100] In the present invention, the recovered cells may be preserved until use. For the preservation, there are two methods, preservation in a liquid state, and cryopreservation. The cryopreservation is usually carried out because the preservation in a liquid state is limited in time to at most 2 to 3 days in the case of, for example, hematopoietic stem cells.

[0101] Next, the cell separation system of the present invention is explained below. The line referred to in the present specification, i.e., the line for introducing the cell-containing fluid into the cell-capturing means which is connected upstream to the inlet of the cell-capturing means is a line connectable to, for example, a container reserving the cell-containing fluid, or a line connectable to a living body tissue in which the cell-containing fluid is present. Specific examples of the former are as follows: a tube equipped with a spike or a tube equipped with a Luer adapter (male or female) is properly selected when the container reserving the cell-containing fluid is a blood bag, or a mere tube is properly selected when connection by a sterilized connector (hereinafter referred to as “SCD connection”) is made. In addition, a needlable tube having a septum is properly selected as the line when the container reserving the cell-containing fluid is a syringe equipped with a needle, or a Luer adapter (female) is properly selected as the line when the container is a syringe having a Luer opening but not a needle. Specific examples of the latter line are as follows, for example, when cord blood is used, the aforesaid living body tissue is umbilical cord and/or placenta, and a tube equipped with a metallic needle stickable into them is mentioned as the latter line. When a tube is used, it may be equipped between its ends with a clamp for opening or shutting the line, a roller clamp for adjusting the flow rate, a mesh chamber for removing aggregates, a syringe for giving the flow rate (including a flow path changing means), etc. When a syringe is used, it may be directly connected to the inlet of the cell-capturing means without a tube.

[0102] The other line referred to in the present specification, i.e., the line for introducing a liquid into the aforesaid cell-capturing means which is connected downstream to the outlet of the aforesaid cell-capturing means, includes lines which are classified as follows according to whether a container containing the liquid to be introduced into the cell-capturing means has been previously connected or is subsequently connectable, and according to the means used for introducing the liquid. That is, when the container containing the liquid to be introduced into the cell-capturing means is previously connected, the line includes, for example, a tube equipped with a bag, and a syringe. In the case of such a bag, a method for introducing the liquid into the cell-capturing means includes a method utilizing the fall of the liquid, a method of squeezing the bag, a method using a roller pump, etc. When the container containing the liquid to be introduced into the cell-capturing means is connected afterwards, the following tubes are selected. When a syringe is used, the line includes a needlable tube having a septum, a tube equipped with a Luer adapter (female), a tube equipped with a three-way stopcock, etc., to which the syringe can be connected. When a bag is used, a line connectable to the bag, i.e., a tube equipped with a spike, or a tube equipped with a Luer adapter (male or female) is properly selected as the aforesaid line. When SCD connection is made, a mere tube is properly selected as the aforesaid line. When a syringe is used, it may be directly connected to the outlet of the cell-capturing means without a tube.

[0103] The other line referred to in the present specification, i.e., the line for recovering cells from the inlet side of the aforesaid cell-capturing means which is connected upstream to the inlet of the aforesaid cell-capturing means, includes lines which are classified as follows according to a container for recovering cells which flow out of the cell-capturing means. That is, when the cells are recovered into a bag, a line connected or connectable to the bag, i.e., a tube equipped with a spike or a tube equipped with a Luer adapter (male or female) is properly selected as the aforesaid line. When SCD connection is made, a mere tube is properly selected as the aforesaid line. When the cells are collected into a conical tube, any open-ended line may be used. When the cells are collected by using a syringe having a Luer opening, a Luer adapter (female), a three-way stopcock and the like are used. When a syringe is used, it may be directly connected to the inlet of the cell-capturing means without a tube.

[0104] Instead of this other line, for example, a container for recovering the cells which flow out of the cell-capturing means is preferably able to withstand freezing and thawing, such as a freeze bag, because the transfer of the cells to a freeze bag can then be omitted. Examples of cryopreservation bags are freeze bags such as “Cryocyte” manufactured by Baxter, “Cell Freeze Bag” manufactured by Charter Med, “Hemo Freeze Bag” manufactured by NPBI, etc.

[0105] To the cell separation system according to the present invention, a line for introducing a liquid into the cell-capturing means may be added in order to rinse away a slight amount of cells to be removed which remain in the cell-capturing means, before recovering cells captured by the cell-capturing means. This line includes lines which are classified as follows according to whether a container containing the liquid is previously connected, or subsequently connectable, and according to the means for introducing the liquid. That is, when the container containing the liquid is previously connected, the line includes, for example, a tube equipped with a bag, and a syringe. When the container containing the liquid is connected afterwards, the following types of tubes are selected. When a syringe is used, the line includes a needlable tube having a septum, and a tube equipped with a Luer adapter (female), to which the syringe can be connected. When a bag is used, a line connectable to the bag, i.e., a tube equipped with a spike or a tube equipped with a Luer adapter (male or female) is properly selected as the line. When an SCD connection is made, a mere tube is properly selected as said line. When a syringe is used, it may be directly connected to the outlet of the cell-capturing means without a tube. Although the position of connecting said line to the cell-capturing means may be on either the inlet side or the outlet side, it is preferably on the inlet side from the viewpoint of ease of operation.

[0106] The present cell separation system, may have a line added for collecting cells (or their constituents) remaining in the cell-capturing means by further introducing a liquid after recovering cells to be recovered. In the case where cells different in purpose of use from the first recovered cells are recovered, for example, in the case where a solution capable of lysing or disrupting cells is used for collecting cells (or their constituents) remaining in the cell-capturing means for HLA typing, the line should comprise a means for changing the flow path, and a plurality of branches so that the cells (or their constituents) collected afterward will not be mixed with the first recovered cells. The flow path changing means may include clamps, spikes, etc.

[0107] The cell separation method using the above-mentioned line system comprises steps of introducing, through a line connected upstream, a cell-containing fluid containing cells to be recovered and cells to be removed into a cell-capturing means capable of substantially capturing the cells to be recovered and substantially permitting passage of the cells to be removed. The resulting fluid containing the cells to be removed is taken out through the outlet of the cell-capturing means, and then a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s is introduced into the cell-capturing means through a line connected downstream from the outlet of the cell-capturing means in order to recover the cells. When the recovered cells are preserved, the line (e.g. a freeze bag) connected upstream to the inlet of the cell-capturing means and containing the cells recovered, is sealed up and separated. The sealing-up and separation are carried out, for example, as follows: the line is sealed up by heat fusion using a heat sealer or the like, and then cut off, or a tube connected through a Luer adapter is detached from the main body and then heat-fused by using a heat sealer or the like. In any case, the term “sealing-up and separation” does not specify the order of operations (e.g. sealing-up followed by separation) at all.

[0108] The present invention further provides a liquid which contains hematopoietic stem cells which is substantially free from erythrocytes and/or platelets, and has a viscosity of not more than 500 mPa·s and not less than 5 mPa·s. The expression “substantially free from” used here means that this cell-containing fluid is prepared by removing 60% or more of erythrocytes and/or platelets from a starting cell-containing fluid. Although cord blood contains erythrocytes in addition to hematopoietic stem cells, a hematopoietic stem cell suspension containing substantially no erythrocyte can be provided by employing the cell separation method of the present invention. Furthermore, the cell-containing fluid may contain a cryopreservative agent.

[0109] The present invention still further provides a liquid containing cells to be recovered and substantially no cells to be removed which is obtained by a cell separation method comprising steps of introducing a cell-containing fluid containing cells to be recovered and cells to be removed, into a cell-capturing means capable of substantially capturing said cells to be recovered and substantially permitting passage there-through of said cells to be removed. The resulting fluid containing the cells to be removed is taken out of the cell-capturing means, and then a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s is introduced into the cell-capturing means to recover the cells which have been captured by the cell-capturing means. When the separation method of the present invention is applied to a suspension containing cells to be recovered and cells to be removed, it becomes possible to efficiently provide a suspension substantially comprising the cells to be recovered.

[0110] The present invention still further provides a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s as a liquid for recovering captured cells from a cell-capturing means. This liquid is preferably one which can be used also as a preservative for cells. In the case of preservation in a liquid state, specific examples of the preservative are sugars (e.g. glucose), nutriments (e.g. various media for cell culture), cell membrane protecting components (e.g. albumin), and combinations of a nutrient and a cell membrane protecting component (e.g. plasma). In the case of cryopreservation, the preservative includes cryoprotectants, in addition to the above examples. The cryoprotectants are classified into two categories, 1) extracellular cryoprotectants, and 2) intracellular cryoprotectants, according to the action mechanism. In the first category, water-soluble polymers such as hydroxyethyl starch, dextran, and poly(vinylpyrrolidone)s, etc. are generally used. In the second category, low-molecular weight organic compounds such as dimethyl sulfoxide, and glycerol, etc. are generally used.

[0111] An embodiment of the cell separation system according to the present invention is explained below with reference to the drawings, which should not be construed as limiting the scope of the invention.

[0112] FIG. 1 shows one embodiment of the cell separation system according to the present invention. In this system, all of the following connections are made by the use of spikes: the connection of a starting-cell bag (containing a cell-containing fluid containing cells to be recovered and cells to be removed) to the main body of the system of the present invention; the connection of a bag for recovering a fluid which flows out through the outlet of a cell-capturing means, to the main body of the system of the present invention; and the connection of a bag for recovering cells from the outlet side of the cell-capturing means, to the main body of the system of the present invention. In the system, there is a three-way stopcock provided to which a syringe with a male Luer opening is connected for introducing a liquid into the cell-capturing means.

[0113] In FIG. 1, numeral 1 denotes the cell-capturing means capable of substantially capturing the cells to be recovered and substantially permitting passage there-through of the cells to be removed. Numeral 2 denotes a line for introducing the cell-containing fluid into the cell-capturing means from the starting-cell bag, which comprises a spike 2-1, a clamp 2-2 and a tube 2-3. Numeral 3 denotes a line for discharging the fluid which flows out through the outlet of the cell-capturing means 1, which comprises a spike 3-1 and a tube 3-2. Numeral 4 denotes a line for introducing the liquid into the cell-capturing means from the outlet side of the cell-capturing means 1, which shares the tube with the line 3 and has the three-way stopcock 4-1 to which the syringe is connected. Numeral 5 denotes a line for recovering cells from the inlet side of the cell-capturing means, which comprises a spike 5-1, clamp 5-2, a tube 5-3 and a part of the tube 2-3. This line shares the tube 2-3 with the line 2 from the inlet of the cell-capturing means 1 to the point at which the tube 5-3 diverges from the tube 2-3.

[0114] Next, a method for using the cell-capturing means is explained below. Initially, the clamp 2-2 is shut, the three-way stopcock 4-1 is closed only in the direction of syringe connection, and the clamp 5-2 is closed. Then, the spike 2-1 is stuck into the starting-cell bag and the spike 3-1 is stuck into an empty bag. When the clamp 2-2 is opened, the cell-containing fluid is supplied to the cell-capturing means 1 through the tube 2-3 of the line 2. The cells to be recovered are captured and the cells to be removed are taken out and then collected in the empty bag through the tube 3-2 of the line 3. After completion of the treatment of the cell-containing fluid, the clamp 2-2 is closed, and the spike 2-1 is pulled out of the starting-cell bag and stuck into a commercially available bottle of physiological saline. When the clamp 2-2 is opened, the physiological saline rinses the cell-capturing means 1 and is collected in the bag containing the collected cells to be removed, through the line 3. After completion of the rinsing, the clamp 2-2 and the tube 3-2 are closed. Subsequently, a syringe containing a liquid with a viscosity of not more than 500 mPa·s and not less than 5 mPa·s is connected to the three-way stopcock 4-1, and the spike 5-1 is stuck into a cell-recovering bag. The three-way stopcock is turned in such a direction that the syringe communicates only with the cell-capturing means 1. After the clamp 5-2 is opened, the piston of the syringe is pushed to introduce the liquid into the cell-capturing means 1 from its outlet side, whereby the cells captured by the cell-capturing means are recovered into the cell-recovering bag through the line 5.

[0115] The present invention is illustrated below in further detail with reference to examples, which should not be construed as limiting the scope of the invention.

EXAMPLE 1

[0116] This working example shows an example of cell separation in the case where a cell-containing fluid was cord blood, cells to be recovered are a mononuclear cell fraction containing hematopoietic stem cells, and cells to be removed are erythrocytes and platelets.

[0117] (1) Cell Separator

[0118] A polycarbonate container with outside dimensions (length×width×thickness) of 41×41×18 mm having a liquid outlet and a liquid inlet on the diagonal was packed with 12 polyester non-woven fabrics with an average fiber diameter of 2.3 μm on the inlet side and 25 polyester non-woven fabrics with an average fiber diameter of 12 μm on the outlet side. The packing density was 0.24 g/cm3, the effective filtration area 9 cm2, and the effective filtration length 12.4 mm. In order to impart platelet permeability to the resulting filter, coating with a hydrophilic polymer was carried out. In detail, a 1% ethanolic solution of a hydroxyethyl methacrylate_dimethylaminoethyl methacrylate copolymer (molar ratio between, hydroxyethyl methacrylate and dimethylaminoethyl methacrylate=97:3) was passed through the filter from the inlet side of the filter, after which the filter was dried by introducing nitrogen gas thereinto.

[0119] (2) Preparation of a Recovering Liquid

[0120] A commercially available solution of dextran 40 in physiological saline (Dextran 40 Injection-Midori, a trade name, available from Green Cross Corp.) was incorporated with human serum albumin to prepare a liquid containing 4% human serum albumin as recovering liquid A. This recovering liquid A was diluted 1.2-fold or 1.3-fold with physiological saline to obtain recovering liquid B and recovering liquid C, respectively. The viscosities of the recovering liquids are as follows: recovering liquid A 10.5 mPA·s, recovering liquid B 8.0 mPA·s, recovering liquid C 5.3 mPA·s.

[0121] (3) Cell Separation Procedure and Line System

[0122] 200 Milliliters of cord blood collected from a placenta and umbilical cord after delivery and containing 15 vol % CPD was divided into four portions, and an experiment was carried out at 4 recovering liquid viscosity values (including that in Comparative Example 1) by using the same blood divided.

[0123] As shown in FIG. 2, a blood bag was connected to the inlet side of the cell separator 6 produced in the above item (1), through a tube having between its ends a three-way stopcock 9 having a bag for cell recovery 10 connected thereto, a mesh chamber 8, and a diverging point to a tube equipped with a spike 13 to be connected to a bottle of physiological saline for rinsing. A drain bag 12 was connected to the outlet side of the cell separator 6 through a tube having between its ends a three-way stopcock 11 for connecting a syringe for recovery.

[0124] A fluid containing nucleated cells in the starting-blood bag 7 was introduced into the cell separator at a head of about 60 cm, and a fluid containing erythrocytes and platelets which had flowed out of the cell separator 6 was discharged into the drain bag 12. Then, the spike 13 was stuck into the bottle of physiological saline, and the clamp 14 was opened, whereby the inside of the filter was rinsed with about 20 ml of physiological saline to rinse away a slight amount of erythrocytes and platelets, which remained in the filter. Subsequently, a 30-ml disposable syringe containing 25 ml of each recovering liquid was connected to the three-way stopcock 11, and the three-way stopcock 11 was turned in such a direction that the syringe communicated only with the cell separator. The three-way stopcock 9 was turned in such a direction that the cell separator 6 communicated only with the bag for cell recovery 10. Then, the piston of the syringe was pushed to recover cells captured in the cell separator, into the bag for cell recovery 10.

[0125] (4) Analysis

[0126] The number of nucleated cells, the number of mononuclear cells, the number of erythrocytes, and the number of platelets were determined with an automatic hemocytometer. The percentage of CD34-positive cells based on the total number of nucleated cells was measured by the use of FITC-labeled anti-CD34 antibody according to a flow cytometry method comprising display on SSC-FITC (Miyazaki et al. “Nichijo Shinryo to Ketsueki (Practical Hematology)” Vol. 5, No. 2, pp. 21-24, 1995).

[0127] The recovery and the removal rate were calculated by the following equations: 1$\mathrm{Recovery}\left(\%\right)=100\times \left(\mathrm{number}\mathrm{of}\mathrm{recovered}\mathrm{cells}/\mathrm{number}\mathrm{of}\mathrm{cells}\mathrm{in}\mathrm{starting}\mathrm{cell}\mathrm{population}\right)$$\mathrm{Removal}\mathrm{rate}\left(\%\right)=100-100\times \left(\mathrm{number}\mathrm{of}\mathrm{recovered}\mathrm{cells}/\text{\&IndentingNewLine;}\mathrm{number}\mathrm{of}\mathrm{cells}\mathrm{in}\mathrm{starting}\mathrm{cell}\mathrm{population}\right)$

[0128] (5) Results

[0129] The time required for pushing the piston of the syringe completely was 3 seconds. The linear speed was calculated to be 55.6 cm/min. The results are summarized in Table 1. It can be seen that nucleated cells, mononuclear cells and CD34-positive cells could be recovered at high percentages in the cell suspension recovered, and that erythrocytes and platelets were removed at high percentages.

	TABLE 1
	Recovery (%)
Recovering			CD34-
liquid	Nucleated	Mononuclear	positive	Removal rate (%)
(mPa · s)	cell	cell	cell	Erythrocyte	Platelet
A (10.5)	75.2	90.2	97.0	99.0	88.0
B (8.0)	74.0	90.0	96.6	99.0	88.0
C (5.3)	73.0	89.6	95.5	99.0	88.0

[0130] The cells recovered by the use of the recovering liquid could be subjected to cryopreservation according to the protocol described in an instruction mannual for a cryopreservative agent “CP-1” manufactured by Kyokuto Pharmaceutical Industrial Co., Ltd. In detail, dimethyl sulfoxide was added to the recovered cell suspension to adjust its final concentration to 5%, and the resulting mixture was subjected to cryopreservation in a deep-freezer at −80° C. After 30 days of cryopreservation, the mixture was rapidly thawed in a warm bath at 37° C., and the cell viability was measured by a conventional trypan blue exclusion method and found to be maintained at a high value of 90.4%.

COMPARATIVE EXAMPLE 1

[0131] In this comparative example, results obtained by using a recovering liquid with a low viscosity containing no dextran were compared with those obtained in Example 1, though as in Example 1, a cell-containing fluid was cord blood, cells to be recovered are a mono-nuclear cell fraction containing hematopoietic stem cells, and cells to be removed are erythrocytes and platelets.

[0132] (1) Cell Separator

[0133] The same cell separator as in Example 1 was used.

[0134] (2) Cell Separation Procedure and Line System

[0135] One of the portions of the cord blood obtained in Example 1 was used as starting cord blood. The process of Example 1 was repeated except for using 25 ml of physiological saline as a recovering liquid. The same line system as in Example 1 was used. The viscosity of the recovering liquid was 1.0 mPa·s.

[0136] (3) Analysis

[0137] The same analysis as in Example 1 was carried out.

[0138] (4) Results

[0139] The time required for pushing the piston of the syringe completely was 3 seconds. The results are summarized in Table 2. The recoveries of nucleated cells, mononuclear cells and CD34-positive cells in the cell suspension recovered were lower than in Example 1.

	TABLE 2
	Recovery (%)
Recovering			CD34-
liquid	Nucleated	Mononuclear	positive	Removal rate (%)
(mPa · s)	cell	cell	cell	Erythrocyte	Platelet
Physio-	31.0	40.0	45.0	99.0	89.7
logical
saline
(1.0)

EXAMPLE 2

[0140] This working example shows an example of cell separation in the case where a cell-containing fluid was peripheral blood, cells to be recovered are leukocytes, and cells to be removed are erythrocytes and platelets.

[0141] (1) Cell Separator

[0142] A polycarbonate container with outside dimensions (length×width×thickness) of 41×41×18 mm having a liquid outlet and a liquid inlet on the diagonal was packed with 25 polyester non-woven fabrics with an average fiber diameter of 12 μm on the inlet side and 12 polyester non-woven fabrics with an average fiber diameter of 2.3 μm on the outlet side. The packing density was 0.24 g/cm3, the effective filtration area 9 cm2, and the effective filtration length 12.4 mm. In order to impart platelet permeability to the resulting filter, coating with a hydrophilic polymer was carried out. A 1% ethanolic solution of a hydroxyethyl methacrylate dimethylaminoethyl methacrylate copolymer (molar ratio between hydroxyethyl methacrylate and dimethylaminoethyl methacrylate=97:3) was passed through the filter from the inlet side of the filter, after which the filter was dried by introducing nitrogen gas thereinto.

[0143] (2) Cell Separation Procedure

[0144] Into the cell separator produced was introduced 50 ml of whole peripheral blood (containing 15 vol % CPD) of a healthy person through the liquid inlet by utilizing the head (about 60 cm; flow rate about 5 ml/min.). Thereafter, 30 ml of physiological saline was passed through the cell separator by means of head (about 60 cm) in order to rinse away erythrocytes and platelets, which remained in the cell separator. Then, 30 ml of a 3.5% solution of a poly(vinylpyrrolidone) (average molecular weight: 360,000) in physiological saline was introduced into the cell separator at a rate of 100 ml/min. through the liquid outlet by the use of a pump, and cells were recovered through the liquid inlet. The viscosity of this recovering liquid was 20.3 mPa·s.

[0145] (3) Analysis

[0146] The number of leukocytes, the number of erythrocytes and the number of platelets were determined with an automatic hemocytometer.

[0147] (4) Results

[0148] The results are summarized in Table 3. Leuko-cytes were recovered at a high percentage in the cell suspension recovered, and erythrocytes and platelets were removed at high percentages. The linear speed was calculated to be 11.1 cm/min.

TABLE 3
Recovery (%)	Removal rate (%)
Leucocyte	Erythrocyte	Platelet
75.0	99.1	90.3

EXAMPLE 3

[0149] This working example shows an example of cell separation in the case where a cell-containing fluid was cord blood, cells to be recovered are hematopoietic stem cells (CD34-positive cells), and cells to be removed are erythrocytes and platelets.

[0150] (1) Cell Separator

[0151] A polycarbonate container with outside dimen-sions (length×width×thickness) of 41×41×18 mm having a liquid outlet and a liquid inlet on the diagonal was packed with 12 polyester non-woven fabrics with an average fiber diameter of 12 μm on the inlet side and 25 polystyrene non-woven fabrics with an average fiber diameter of 2.3 μm having anti-human CD34 monoclonal mouse antibody (clone name: Immu133, available from Coulter Corp.; hereinafter abbreviated as “CD34 antibody”) immobilized thereon, on the outlet side. The packing density of the resulting filter was 0.2 g/cm3. The immobilization of the anti-human CD34 monoclonal mouse antibody on the polystyrene was carried out by the well-known haloacetamide method proposed in JP-A-2-261833. In detail, polystyrene non-woven fabrics (previously cut to the above-mentioned dimensions) were immersed in a treating solution prepared by adding 3.6 g of hydroxy-methyliodoacetamide and 25 g of trifluoromethanesulfonic acid to 165 ml of sulfolane, at room temperature for 5 hours to be reacted, for the purpose of activating the polystyrene, non-woven fabrics. The non-woven fabrics thus activated were washed with D-PBS, after which, in order to immobilize the antibody on them, they were immersed for 2 hours in 10 ml of a CD34 antibody solution having a concentration adjusted to 20 μg/ml with D-PBS, and they were washed with D-PBS and then freeze-dried, whereby the non-woven fabrics having the antibody immobilized thereon were obtained.

[0152] (2) Preparation of a Recovering Liquid

[0153] A commercially available solution of dextran 40 in physiological saline (Dextran 40 Injection-Midori, a trade name, available from Green Cross Corp.) was incorporated with human serum albumin to prepare a liquid containing 4% human serum albumin as a recovering liquid. The viscosity of the recovering liquid was 9.8 mPa·s.

[0154] (3) Cell Separation Procedure

[0155] A blood bag containing 50 ml of fresh human cord blood (containing 15 vol % of an anticoagulant CPD) was connected to the inlet side of the cell separator produced in the above item (1), through a tube having between its ends, diverging points to a physiological saline bag and a bag for cell recovery, respectively. A blood bag for drain was connected to the outlet side of the cell separator through a tube having a three-way stopcock between the ends of the tube. Into the cell separator was introduced 50 ml of the fresh cord blood by utilizing its fall (about 60 cm), and an erythrocyte-containing fluid (also containing CD34-negative cells and platelets) which had flowed out of the filter was recovered into the drain bag. Then, 30 ml of physiological saline was passed through the filter in order to rinse away erythrocytes, platelets and CD34-negative cells, which remained in the filter.

[0156] Subsequently, a syringe containing 30 ml of the recovering liquid prepared in the above item (2) was connected to the three-way stopcock of the tube on the outlet side of the cell separator, and the recovering liquid was introduced into the cell separator by pushing the piston of the syringe, to recover the captured cells into the bag connected to the inlet side.

[0157] (3) Analysis

[0158] The same analysis as in Example 1 was carried out.

[0159] (4) Results

[0160] The time required for pushing the piston of the syringe completely was 3 seconds. The linear speed was calculated to be 55.6 cm/min. The results are summarized in Table 4. It can be seen that CD34-positive cells could be recovered at a high percentage in the cell suspension recovered, and that erythrocytes, platelets and CD34-negative cells were removed at high percentages.

	TABLE 4
	Recovery (%)	Removal rate (%)
	CD34-positive			CD34-negative
	cell	Erythrocyte	Platelet	cell
	78	99.2	90.4	90

EXAMPLE 4

[0161] This working example shows an example of cell separation in the case where a cell-containing fluid was cord blood, cells to be recovered are a mononuclear cell fraction containing hematopoietic stem cells, cells to be removed are erythrocytes and platelets, and DNA for HLA typing was collected at the same time.

[0162] (1) Cell Separator

[0163] The same cell separator as in Example 1 was used.

[0164] (2) Preparation of Recovering Liquids

[0165] A commercially available solution of dextran 40 in physiological saline (Dextran 40 Injection-Midori, a trade name, available from Green Cross Corp.) was incorporated with human serum albumin to prepare a liquid containing 4% human serum albumin as a first recovering liquid (for cell recovery). Distilled water for injection, and a hypotonic liquid was used as an additional recovering liquid (for recovering cell constituents). The viscosity of the first recovering liquid was 10.5 mPa·s.

[0166] (3) Line System

[0167] The cell separation system shown in FIG. 3 was obtained by incorporating the cell separator described in the above item (1) into lines. In this system, the connection of a cell-containing fluid bag to the main body of the system of the present invention, and the connection of a bag for recovering a fluid which flows out through the outlet of the cell separator 15, to the main body of the system of the present invention were made with spikes. A line for recovering cells from the inlet side of the cell-capturing means was equipped with a freeze bag for recovering cells for cell transfer, and a tube with a spike at the end for recovering DNA for HLA typing into a conical tube. In this line, the flow paths are changed by means of clamps.

[0168] (4) Cell Separation Procedure

[0169] A cell separation procedure was carried out by using the line system shown in FIG. 3.

[0170] Initially, clamp 21 was shut, a three-way stopcock 25 was shut only in the direction of syringe connection, and clamps 27 and 28 were shut.

[0171] A spike 20 was stuck into a blood bag containing 50 ml of fresh human cord blood (containing 15 vol % of an anticoagulant CPD), and a spike 23 was stuck into an empty bag. When the clamp 21 was opened, the cell-containing fluid was supplied to the cell separator 15 through the tube 22 of a line 16, and a mononuclear cell fraction containing hematopoietic stem cells was captured, and erythrocytes and platelets were discharged into the empty bag through the tube 24 of a line 17.

[0172] After completion of the treatment of said cell-containing fluid, the clamp 21 was shut and the spike 20 was pulled out, and then stuck into a commercially available 100-ml bottle of physiological saline. When the clamp 21 was opened, the physiological saline rinsed away a slight amount of erythrocytes and platelets, which remained in the cell separator 15, and the physiological saline was discharged through the line 17. Then, the clamp 21 was shut. Next, a 30-ml syringe containing 25 ml of the recovering liquid prepared in the above item (2) was connected to the three-way stopcock 25, after which the three-way stopcock 25 was turned in such a direction that the syringe communicated only with the cell-capturing means 15 through a line 18, and the clamp 27 was opened. The piston of the syringe was pushed to recover cells into a freeze bag 29 through a line 19. Subsequently, the syringe was detached from the three-way stopcock 25, and another syringe containing 25 ml of distilled water for injection was connected to the three-way stopcock 25. The clamp 27 was shut, and clamp 28 was opened, being attached to a tube 31 capable of communicating with the tube 32 of the line 19 through a Y-tube 26. A conical tube was placed under a spike 30, after which the distilled water for injection was introduced into the cell-capturing means by pushing the piston of the syringe, to disrupt the captured cells, and crude DNA in these cells was recovered in the conical tube. The crude DNA recovered was purified by a conventional method comprising deproteination using proteinase K and phenol chloroform method.

[0173] (5) Analysis

[0174] The numbers of cells were determined by the same method as described in Example 1. The amount of the purified DNA was determined by a conventional method comprising measuring absorbance at 260 nm by means of a spectrophotometer (Nakayama et al., Cell Technology, extra issue “Bio-experiment Illustrated” (1) Fundamentals of Molecular Biological Experiment, 1995).

[0175] (6) Results

[0176] The time required for pushing the piston of the syringe completely was 3 seconds. The linear speed was calculated to be 55.6 cm/min. The results are summarized in Table 5. It can be seen that eukaryotic cells, mononuclear cells and CD34-positive cells could be recovered at high percentages in the cell suspension recovered, and that erythrocytes and platelets were removed at high percentages. It can also be seen that the amount of the DNA obtained was about 10 μmg, an amount sufficient for HLA typing.

TABLE 5
Recovery(%)
	Mono-	CD34-		Amount of
Nucleated	nuclear	positive	Removal rate (%)	purified
cell	cell	cell	Erythrocyte	Platelet	DNA (μg)
75.0	90.4	97.2	98.9	88.3	9.8

EXAMPLE 5

[0177] This working example shows an example of cell separation in the case where a cell-containing fluid was bone marrow, cells to be recovered are a mononuclear cell fraction containing hematopoietic stem cells, and cells to be removed are erythrocytes and platelets.

[0178] (1) Cell Separator

[0179] The same cell separator as in Example 1 was used.

[0180] (2) Preparation of a Recovering Liquid

[0181] A commercially available solution of dextran 40 in physiological saline (Dextran 40 Injection-Midori, a trade name, available from Green Cross Corp.) was incorporated with human serum albumin to prepare a liquid containing 4% human serum albumin as a recovering liquid. The viscosity of the recovering liquid was 101 mPa·s.

[0182] (3) Cell Separation Procedure and Line System

[0183] As shown in FIG. 2, a blood bag containing 30 ml of bone marrow (containing 15 units/ml of an anticoagulant heparin) was connected to the inlet side of the cell separator 6 described in the item (1), through a tube having between its ends a three-way stopcock 9 having a bag for cell recovery 10 connected thereto, a mesh chamber 8, and a diverging point to a tube with a spike 13 to be connected to a bottle of physiological saline for rinsing. A drain bag 12 was connected to the outlet side of the cell separator 6 through a tube having between its ends a three-way stopcock 11 for connecting a syringe for recovery. The fluid containing nucleated cells in the starting-blood bag 7 was introduced into the cell separator at a fall of about 60 cm, and a fluid containing erythrocytes which had flowed out of the cell separator 6 was discharged into the drain bag 12. Then, the spike 13 was stuck into the bottle of physiological saline, and the clamp 14 was opened, whereby the inside of the filter was rinsed with about 20 ml of physiological saline to rinse away a slight amount of erythrocytes and platelets, which remained in the filter. Subsequently, a 30-ml disposable syringe containing 25 ml of the recovering liquid was connected to the three-way stopcock 11, and the three-way stopcock 11 was turned in such a direction that the syringe communicated only with the cell separator. The three-way stopcock 9 was turned in such a direction that the cell separator 6 communicated only with the bag for cell recovery 10. Then, the piston of the syringe was pushed to recover cells captured in the cell separator, into the bag for cell recovery 10.

[0184] (4) Analysis

[0185] The number of nucleated cells, the number of mononuclear cells, the number of erythrocytes and the number of platelets were determined with an automatic hemocytometer. The percentage of CD34-positive cells based on the total number of nucleated cells was measured by the use of FITC-labeled anti-CD34 antibody according to a flow cytometry method comprising development on SSC-FITC (Miyazaki et al. “Nichijo Shinryo to Ketsueki (Routine Diagnosis and Treatment, and Blood)” Vol. 5, No. 2, pp. 21-24, 1995).

[0186] The recovery and the removal rate are calculated by the following equations: 2$\mathrm{Recovery}\left(\%\right)=100\times \left(\mathrm{number}\mathrm{of}\mathrm{recovered}\mathrm{cells}/\mathrm{number}\mathrm{of}\mathrm{cells}\mathrm{in}\mathrm{starting}\mathrm{cell}\mathrm{population}\right)$$\mathrm{Removal}\mathrm{rate}\left(\%\right)=100-100\times \left(\mathrm{number}\mathrm{of}\mathrm{recovered}\mathrm{cells}/\text{\&IndentingNewLine;}\mathrm{number}\mathrm{of}\mathrm{cells}\mathrm{in}\mathrm{starting}\mathrm{cell}\mathrm{population}\right)$

[0187] (5) Results

[0188] The time required for pushing the piston of the syringe completely was 3 seconds. The linear speed was calculated to be 55.6 cm/min. The results are summarized in Table 6. It can be seen that nucleated cells, mononuclear cells and CD34-positive cells could be recovered at high percentages in the cell suspension recovered, and that erythrocytes and platelets were removed at high percentages.

TABLE 6
Recovery (%)
	Mono-	CD34-
Nucleated	nuclear	positive	Removal rate (%)
cell	cell	cell	Erythrocyte	Platelet
74.3	91.2	97.6	99.0	88.0

[0189] The present invention will be explained in more detail below by the following Examples, but the present invention is not limited by these Examples.

[0190] Following Examples and Comparative Examples illustrate methods for separating monocytes from cord blood.

EXAMPLE 6

[0191] (1) Preparation of a Cell Separation Filter

[0192] From the inlet side of a polycarbonate vessel, consisting of an upper vessel and a lower vessel, with inner size after assembled: 43 mm in length, 43 mm in width, 2.9 mm in height (cross section of effective filtering area of 18.5 cm2 and inner volume of 7 cm3), having a fluid outlet and a fluid inlet on the longest diagonal line, 1.37 g of polyester non-woven fabric having mean fiber diameter of 1.7 μm was packed in the first layer and 0.19 g of polyester non-woven fabric having mean fiber diameter of 1.1 μm was packed in the second layer so that they were sandwiched by edges of the upper vessel and the lower vessel, and the spaces for the inlet and outlet sides of the vessel were partitioned. Thickness and packing density of the first layer in the packing were 2.5 mm and 0.24 g/cm3, respectively. Thickness and packing density of the second layer in the packing were 0.4 mm and 0.20 g/cm3, respectively. The value of effective filtering area divided by thickness of the material for capturing nucleated cells in packing step was 74 cm. Said cell separating filter was coated with hydrophilic polymer to provide platelet permeability. Namely, 1 percent ethanol solution of hydroxyethyl methacrylate-dimethylaminoethyl methacrylate copolymer (molar ratio of 97:3) was introduced from the fluid inlet of said cell separation filter, followed by purging the excess polymer solution using nitrogen gas and drying at 60° C. for 8 hours or more in a vacuum drier.

[0193] (2) Cell Separation

[0194] Human cord blood of 100 cm3 added with CPD was introduced using head force from the inlet for the cell-containing fluid to the cell separation filter, and mononuclear cells were captured. Filtered blood was recovered into a drain bottle. Then, a mixed fluid of 19 cm3, prepared by adding human serum albumin to the commercially available 10% dextran physiological saline (Kobayashi Pharm. Co., “Dextran 40 Inj.”) (to final concentration of 3%) and 18 cm3 of air were packed in a syringe, followed by manual fluid introduction from the outlet for the cell-containing fluid, to recover mononuclear cells from the inlet for the cell-containing fluid. Volume of thus recovered cell-containing fluid was 23 cm3 and time required for the recovery was 2 seconds (flow rate: 570 cm3/min.).

[0195] (3) Analysis

[0196] Cell counts in the present cell separation operation were measured using multi-purpose automated hematology analyzer (SF3000 from Sysmex), and recovery rate of mononuclear cells was calculated using the following equation.

Recovery Rate of Mononuclear Cells (%)=100×(mononuclear cell counts in the recovered cell fluid/mononuclear cell counts in cord blood)

[0197] (4) Results

[0198] Recovery rate of mononuclear cells in the present separation operation was 85% and filtering time was 6 min.

EXAMPLE 7

[0199] (1) Preparation of a Cell Separation Filter

[0200] From the inlet side of a polycarbonate vessel, consisting of an upper vessel and a lower vessel, with inner size after assembled: 30 mm in length, 30 mm in width, 12.4 mm in height (cross section of effective filtering area of 9 cm2 and inner volume of 11 cm3), having a fluid outlet and a fluid inlet on the longest diagonal line, 1.32 g of polyester non-woven fabric having mean fiber diameter of 2.3 μm was packed in the first layer and 0.19 g of polyester non-woven fabric having mean fiber diameter of 1.1 μm was packed in the second layer so that they were sandwiched by edges of the upper vessel and the lower vessel, and the spaces for the inlet and outlet sides of the vessel were partitioned. Thickness and packing density of the first layer in the packing were 5.4 mm and 0.20 g/cm3, respectively. Thickness and packing density of the second layer in the packing were 7 mm and 0.20 g/cm3, respectively. The value of effective filtering area divided by thickness of the nucleated cells capturing means in packing step was 16.7 cm. Said non-woven fabric was coated with hydrophilic polymer similarly as in Example 6.

[0201] (2) Cell Separation

[0202] Cell separation was performed similarly as in Example 6. Volume of thus recovered cell-containing fluid was 21 cm3 and time required for the recovery was 3 seconds (flow rate: 380 cm3/min.)

[0203] (3) Results

[0204] Recovery rate of mononuclear cells in the present separation operation was 75% and filtering time was 10 min (flow rate: 10 cm3/min.).

EXAMPLE 8

[0205] (1) Preparation of a Cell Separation Filter

[0206] The same vessel as in Example 1 was used. From the inlet side of the vessel, 0.14 g of polyester non-woven fabric having mean fiber diameter of 12 μm, 1.28 g of polyester non-woven fabric having mean fiber diameter of 1.7 μm and 0.19 g of polyester non-woven fabric having mean fiber diameter of 1.1 μm were packed in the first, the second and the third layer, respectively. Thickness and packing density of the first layer in the packing were 0.3 mm and 0.20 g/cm3, respectively. Thickness and packing density of the second layer in the packing were 2.2 mm and 0.24 g/cm3, respectively. Thickness and packing density of the third layer in the packing were 0.4 mm and 0.20 g/cm3, respectively. The value of effective filtering area divided by thickness of the nucleated cells capturing means in packing step was 84.1 cm. Said non-woven fabric was coated with hydrophilic polymer similarly as in Example 6.

[0207] (2) Cell Separation

[0208] Cell separation was performed similarly as in Example 6. Volume of thus recovered cell-containing fluid was 23 cm3 and time required for the recovery was 2 seconds (flow rate: 570 cm3/min.)

[0209] (3) Results

[0210] Recovery rate of mononuclear cells in the present separation operation was 88% and filtering time was 4 min (flow rate: 25 cm3/min.).

EXAMPLE 9

[0211] (1) Preparation of a Cell Separation Filter

[0212] The same vessel as in Example 1 was used. From the inlet side of the vessel, polyurethane porous body of average 12 μm in packing and polyurethane porous body of average 6 μm in packing were packed in the first and the second layer, respectively. Thickness and void ratio of the first layer in the packing were 2.2 mm and 60%, respectively. Thickness and void ratio of the second layer in the packing were 0.7 mm and 60%, respectively. The value of effective filtering area divided by thickness of the nucleated cells capturing means in packing step was 74 cm. Said polyurethane porous body was coated with hydrophilic polymer similarly as in Example 6.

[0213] (2) Cell Separation

[0214] Cell separation was performed similarly as in Example 6. Volume of thus recovered cell-containing fluid was 23 cm3 and time required for the recovery was 3 seconds (flow rate: 380 cm3/min.)

[0215] (3) Results

[0216] Recovery rate of mononuclear cells in the present separation operation was 84% and filtering time was 6 min (flow rate: 16.7 cm3/min.).

COMPARATIVE EXAMPLE 2

[0217] (1) Preparation of a Cell Separation Filter

[0218] The same vessel as in Example 1 was used. The filter made of polyester non-woven fabric having mean diameter of 1.7 μm was packed in the amount of 1.67 g. Thickness and packing density of the filter in the packing were 2.9 mm and 0.25 g/cm3, respectively. The value of effective filtering area divided by thickness of the nucleated cells capturing means in packing step was 62.1 cm. Said non-woven fabric was coated with hydrophilic polymer similarly as in Example 6.

[0219] (2) Cell Separation

[0220] Cell separation was performed similarly as in Example 6. Volume of thus recovered cell-containing fluid was 23 cm3 and time required for the recovery was 3 seconds (flow rate: 380 cm3/min.)

[0221] (3) Results

[0222] Recovery rate of mononuclear cells in the present separation operation was 65% and filtering time was 7 min (flow rate: 14.3 cm3/min.).

COMPARATIVE EXAMPLE 3

[0223] (1) Preparation of a Cell Separation Filter

[0224] From the inlet side of a polycarbonate vessel, consisting of an upper vessel and a lower vessel, with inner size after assembled: 22 mm in length, 22 mm in width, 12.4 mm in height (cross section of effective filtering area of 5.3 cm2 and inner volume of 7 cm3), having a fluid outlet and a fluid inlet on the longest diagonal line, 1.50 g of polyester non-woven fabric having mean fiber diameter of 1.7 μm was packed in the first layer and 0.3 g of polyester non-woven fabric having mean fiber diameter of 1.1 μm was packed in the second layer. Thickness and packing density of the first layer in the packing were 10 mm and 0.24 g/cm3, respectively. Thickness and packing density of the second layer in the packing were 2.4 mm and 0.20 g/cm3, respectively. The value of effective filtering area divided by thickness of the material for capturing cells having nucleus in packing step was 5.3 cm. Said non-woven fabric was coated with hydrophilic polymer similarly as in Example 6.

[0225] (2) Cell Separation

[0226] Cell separation was performed similarly as in Example 6, but the flow rate was abruptly decreased after the start of the filtering, and filtering was not completed, even after 1 hour or more was passed.

COMPARATIVE EXAMPLE 4

[0227] (1) Preparation of a Cell Separation Filter

[0228] From the inlet side of a polycarbonate vessel, consisting of an upper vessel and a lower vessel, with inner size after assembled: 74.2 mm in length, 74.2 mm in width, 3 mm in height (cross section of effective filtering area of 55 cm2 and inner volume of 16 cm3), having a fluid outlet and a fluid inlet on the longest diagonal line, 3.61 g of polyester non-woven fabric having mean fiber diameter of 1.7 μm was packed in the first layer and 0.58 g of polyester non-woven fabric having mean fiber diameter of 1.1 μm was packed in the second layer. Thickness and packing density of the first layer in the packing were 2.5 mm and 0.24 g/cm3, respectively. Thickness and packing density of the second layer in the packing were 0.5 mm and 0.20 g/cm3, respectively. The value of effective filtering area divided by thickness of the nucleated cells capturing means in packing step was 220 cm. Said non-woven fabric was coated with hydrophilic polymer similarly as in Example 6.

[0229] (2) Cell Separation

[0230] Cell separation was performed similarly as in Example 6. Volume of thus recovered cell-containing fluid was 21 cm3 and time required for the recovery was 3 seconds (flow rate: 380 cm3/min.)

[0231] (3) Results

[0232] Recovery rate of mononuclear cells in the present separation operation was 55% and filtering time was 4 min (flow rate: 33.3 cm3/min.).

[0233] Results of Examples and Comparative Examples were summarized in Table 7.

	TABLE 7
	Effective
	filtration			Recovery
	area/Thickness of		Recovering	rate of
	the nucleated	Recovering	liquid	mono-
	cells capturing	liquid	with	nuclear	Filtering
	means (cm)	dispersing	cells	cells	time
	(In filtration)	(In recovery)	means	(ml)	(%)	(min.)
Example 6	74.0	74.0	Set up	23	85	6
Example 7	16.7	16.7	Set up	21	75	10
Example 8	84.1	84.1	Set up	23	88	4
Example 9	74.0	74.0	Set up	23	84	6
Comparative	62.1	62.1	None	23	65	7
Example 2
Comparative	5.3	5.3	Set up	—	Irrecoverable	Not
Example 3						filtrable
Comparative	220	220	Setup	21	55	4
Example 4

EFFECT OF THE PRESENT INVENTION

[0234] By using the separating method in accordance with the present invention, for nucleated cells, nucleated cells can be recovered from the cell-containing fluid stably with high yield, while suppressing decrease in filtering flow rate of the cell-containing fluid, and furthermore, the objective cells can be recovered simply using smaller fluid volume.

Claims

1. A method for separation of nucleated cells by introducing cell-containing fluid, containing nucleated cells and cells to be removed, into a filter which substantially captures the nucleated cells but substantially passes the cells to be removed, followed by draining the cell-containing fluid to be removed, from the said filter and introducing thus recovering liquid into said filter to recover the nucleated cells, which are captured on the filter, characterized in that a vessel as a filter, having at least an inlet and an outlet of the cell-containing fluid, is packed with nucleated cells capturing means and recovering liquid dispersing means, both consisting of porous materials, in the direction from the inlet side toward the exit side of the cell-containing fluid, in this order; said filter used has value of 15-120 cm, obtained from effective filtration area of said filter divided by thickness of the cell-capturing means in packing step; the nucleated cells in the filter are captured by introducing the cell-containing fluid into the filter from the inlet of the cell-containing fluid, followed by draining the fluid containing the cells to be removed from said filter, and introducing the recovering liquid from the outlet of the cell-containing fluid, to recover the nucleated cells, which are captured in said filter, from the inlet of the cell-containing fluid.

2. The method for separating nucleated cells according to claim 1, wherein aggregates-capturing means is further packed in the inlet side of the cell-containing fluid in said nucleated cells capturing means.

3. The method for separating nucleated cells, according to claim 1, wherein said porous material is non-woven fabric.

4. The method for separating nucleated cells, according to claim 3, characterized in that the nucleated cells capturing means and the recovering liquid dispersing means, both consisting of non-woven fabric are: a) the cell-capturing means, consisting of non-woven fabric with mean fiber diameter of 1.1-3.0 μm and packing density of 0.1-0.3 g/cm3; and b) the recovering liquid dispersing means, consisting of the non-woven fabric with mean fiber diameter of 0.5-1.5 μm and packing density of 0.1-0.3 g/cm3, respectively and mean fiber diameter becomes smaller in the order of the nucleated cells capturing means and the recovering liquid dispersing means.

5. The method for separating nucleated cells, according to claim 1, wherein said porous material has spongy structure.

6. The method for separating nucleated cells, according to claim 5, characterized in that the nucleated cells capturing means and the recovering liquid dispersing means, both consisting of spongy structure, are: a) the cell-capturing means, consisting of spongy structure having mean pore diameter in packing of 7-25 μm and void ratio in packing of 55-90%; and b) the recovering liquid dispersing means, consisting of spongy structure having mean pore diameter in packing of 2-10 μm and void ratio in packing of 55-90%, respectively and mean pore size becomes smaller in the order of the nucleated cells capturing means and the recovering liquid dispersing means.

7. The method for separating nucleated cells, according to claim 1, wherein said porous material is a combination of non-woven fabric and spongy structure.

8. The method for separating nucleated cells, according to claim 2, wherein said porous material is non-woven fabric.

9. The method for separating nucleated cells, according to claim 2, wherein said porous material has spongy structure.