Patent Application
20200222621
The present invention relates to the separation of a biological fluid into its component parts, such as separation of whole blood into red blood cells, white blood cells, platelets and plasma. More specifically the present invention provides a system for use in carrying out such separation.
The components of blood, i.e. red blood cells, white blood cells, platelets and plasma are used for different therapies and therefore a certain amount of donated whole blood is processed in order to separate out these components. In a typical blood donation, around 450 mL of whole blood is collected into a blood collection bag containing an anticoagulant solution. The collected blood is separated into its sub-components by spinning the blood bag for a period of about 10 minutes in a large refrigerated centrifuge. Following centrifugation, each of the components are expressed sequentially from the blood collection bag into separate collection bags.
There has been a desire for more automated, compact and portable systems for collection and separation of biological fluids, that are suitable even for processing relatively small volumes.
U.S. Pat. Nos. 3,737,096 and 4,303,193 propose a relatively small centrifugal apparatus attached to collapsible bags. However, these devices have a minimum fixed holding volume which requires a minimum volume usually of about 250 mL to be processed before any components can be collected.
U.S. Pat. No. 5,316,540 discloses a centrifugal processing apparatus corresponding to the where the processing chamber is a flexible processing bag which can be deformed to fill it with biological fluid or empty it by means of a membrane which forms part of the drive unit.
EP0654669-A discloses a centrifugal processing apparatus having two chambers separated by a piston. Before centrifugation, a small quantity of fluid to be processed is taken in via an off-centre inlet, and is transferred between the two chambers during centrifugal processing.
EP0912250-B1 teaches a portable and disposable centrifugal apparatus with a processing chamber of variable volume. It can therefore process a variable quantity of biological fluid, even down to very small quantities. U.S. Pat. No. 6,733,433 describes a similar apparatus. Both of these documents teach control of the movement of the piston by means of a pneumatic system located at the bottom of the chamber that selectively creates either a vacuum or a positive pressure to move the piston up or down as desired. The present inventors recognise a number of problems with a pneumatic system to control movement of the piston, including:
EP0912250-B1 also suggests use of two peristaltic pumps acting on tubing lines connected to the processing chamber for transferring biological fluid into and out of the chamber. The present inventors recognise that peristaltic pumps may be problematic in that flow jerks are readily generated, which can cause unwanted stress on cells in the biological fluid.
There is therefore scope for a further improved system for processing biological fluids that overcomes these problems.
In one aspect, the present invention provides a system (1) for the separation of a biological fluid into its components, wherein the system (1) comprises:
In another aspect, the present invention relates to use of the system (1) of the invention in a method for the separation of a biological fluid into its components wherein said method comprises:
The system of the present invention overcomes the problems connected with using compressed air to control movement of the axially moveable member, such that the speed of movement can be more finely controlled and reducing or eliminating problems of stick and slip as well as flow jerk during the movement. The present invention reduces reactivity of movement of the axially moveable member and is very sensitive to piston friction. With known methods it is difficult to control the pressure near to 0 mbar (between −100 and +100 mbar), whereas the present invention allows for smooth movement of the axially moveable member under 1 ml/s.
This invention therefore combines the advantages of variable volume with a high quality of regulation of movement of the axially moveable member.
To more clearly and concisely describe and point out the subject matter of the claimed invention, definitions are provided hereinbelow for specific terms used throughout the present specification and claims. Any exemplification of specific terms herein should be considered as a non-limiting example.
The terms “comprising” or “comprises” have their conventional meaning throughout this application and imply that the agent or composition must have the essential features or components listed, but that others may be present in addition. The term ‘comprising’ includes as a preferred subset “consisting essentially of” which means that the composition has the components listed without other features or components being present.
A “biological fluid” in the context of the present invention is taken to mean any treated or untreated fluid associated with a living organism, including, but not limited to blood, saliva, lymph, cerebrospinal fluid, ascites fluid, and urine. Biological fluid particularly includes blood, including whole blood, warm or cold blood, and stored or fresh blood; treated blood, such as blood diluted with a physiological solution, including but not limited to saline, nutrient, and/or anticoagulant solutions. A liquid cell culture may also be regarded as a biological fluid.
The “components” of a biological fluid will be dependent on the particular biological fluid in question but will include cellular components and the liquid in which they are present. So for example, the components of human blood are red blood cells, white blood cells, platelets and plasma, and the components of a liquid cell culture are the cells being grown and the culture medium.
The term “pulse damper” as used herein is intended to be a generic term to refer to a device that intercepts pressure pulses and/or prevents their creation. A pulse damper is positioned generally adjacent to the source of the flow or pressure disturbance, which is typically a modulating element like a pump or a flow control valve. A pulse damper works by collecting the peak flow, and delivering it back to the system when the rate of mass transfer decreases, thus smoothing and averaging the flow. In the system of the present invention the pulse damper is positioned between the chamber and the pump to reduce flow jerks, which can be a problem when flow into the separation chambers is in waves.
A “centrifugal separating chamber” in the context of the present invention is a hollow centrifuge processing chamber rotatable about an axis of rotation by engagement of the processing chamber with a rotary drive unit. Typically, a centrifugal separating chamber is generally cylindrical in shape such that components are separated concentrically. The separating chamber in one embodiment comprises a generally cylindrical wall extending from an end wall of the processing chamber, this generally cylindrical wall defining therein a hollow open cylindrical space coaxial with the axis of rotation, the axial opening being provided in said end wall coaxial with the generally cylindrical wall to open into the hollow processing chamber. The processing chamber contains within the generally cylindrical wall the axially movable member. Typical materials from which a separating chamber can be made include polypropylene (PP), polycarbonate (PC), polyoxymethylene (POM) and liquid silicone rubber (LSR). In one embodiment the walls of the chamber are made from PP, the axially moveable member is made of PC and the seals are made from LSR. Separating chambers are known in the art and commercially available, e.g. from GE Healthcare's Biosafe.
The “walls” of the centrifugal separating chamber define the outer shape of the chamber as well as the hollow interior. The “hollow interior” is the entire internal space defined by the walls of the chamber.
The “axial opening” positioned at the top end of the centrifugal separating chamber is an opening through which biological fluid to be processed enters the chamber and processed components of said biological fluid exit the chamber. It is of a diameter suitable for the biological fluid to readily pass through without causing damage to any of its components. Said axial opening is typically of narrower diameter than the centrifugal separating chamber. This opening leads into a separation space of variable volume wherein the entire centrifugal processing of the biological fluid takes place.
The “axially movable member” is configured to fluidly isolate the separation space from the remainder of the hollow interior of the centrifugal separating chamber. It is moveable to either intake a selected quantity of biological fluid to be processed into the separation space via the axial opening or to express processed biological fluid components from the separation space via said opening. In one embodiment, said axially moveable member is a piston. The separation space of variable volume is defined in an upper part of the processing chamber by the walls of the chamber and the axially movable member. Axial movement of the movable member varies the volume of the separation space, the movable member being axially movable within the processing chamber to intake a selected quantity of biological fluid to be processed into the separation space via the inlet before or during centrifugal processing and to express processed biological fluid components from the separation space via the axial opening after centrifugal processing.
The phrase “at least part of a pump” refers to the fact that a portion of tubing can be regarded as part of the pump. For illustration, non-limiting examples include where the tubing may be acted upon by a peristaltic pump, or it could be a disposable diaphragm (or “membrane”) pump.
The “means for monitoring” the position of the axially movable member comprises a detector responsive to changes in the position of the axially moveable member connected to control circuitry. In one embodiment the means for monitoring comprises an optical sensor assembly made from a vertical array of light-emitting diodes, e.g. with light emitting in the infrared spectrum to avoid interference from ambient light. The control circuitry comprises software that includes instructions for operation of the detector. In certain embodiments the control circuitry may take the form of software programmed into a desktop computer, a laptop computer or a smartphone.
Each of said “plurality of containers” is a container suitable for the collection and/or storage of a biological fluid or one of its components. In one embodiment each of said containers is a plastic bag of the type well-known in the field of blood collection and storage.
The term “additive solutions” may be taken to encompass any solution useful in blood collection and storage, e.g. anticoagulant solutions, preservatives, buffers.
The term “in fluid communication” takes its ordinary meaning, which is to say that a fluid may readily pass from one component to the other, either directly or by means of a conduit such as a pipe or tube. The term “in selective fluid communication” means that the path between two components can be selectively closed.
The “plurality of valves” is a distribution valve arrangement that establishes selective communication between the separating chamber and the plurality of containers or for placing the processing chamber and each of the containers either in or out of communication.
A “pump” in the context of the present invention is an apparatus for moving fluid by means of a piston, plunger, or set of rotating vanes.
The term “transferring” as applied to use of the system of the present invention refers to the process of moving the biological fluid into the separation space or of moving the separated components out of the separation space. The act of transferring should be carried out in a manner that causes little to no damage to the components of the biological fluid as it is required for therapeutic applications that these components are intact. Movement of the axially moveable member downwardly in the separation chamber creates a vacuum to intake liquid, and its movement upwardly facilitates transfer of the separated components into their respective containers.
The word “rotating” as it applies to use of the separation chamber means rotation to speeds suitable for separating a biological fluid into its components within the separation chamber. In one embodiment, a “speed suitable for centrifugal separation” of the biological fluid is in the range 4000-8000 rpm, preferably 5000-7000 rpm, more preferably 5500-6500 rpm.
In one embodiment of the system (1), said pulse dampener (70) comprises an air cavity positioned above said tubing (50). This “air cavity” can be understood to be an air space above the fluid wherein the air acts upon the fluid flow to smooth out flow jerks. By way of illustration, non-limiting examples include where the air cavity is separated from the fluid flow in the tubing by a diaphragm, or where the air cavity is part of a drip chamber with fluid in the bottom where the air takes up the changes in pressure. In one embodiment, said pulse dampener (70) is an air spring. In one embodiment, said pulse dampener (70) is a drip chamber.
In one embodiment, said air cavity is separated from the interior of said tubing (50) by a diaphragm.
In another embodiment of the system (1), said pulse dampener (70) comprises a piston backed by a mechanical spring.
In one embodiment of the system (1), said separating chamber (10) is substantially cylindrical. In one embodiment, the walls (11) of said separating chamber (10) are formed from rigid plastic. In one embodiment, said rigid plastic is polypropylene.
In one embodiment of the system (1), said axially moveable member (20) is formed from rigid plastic. In one embodiment, said rigid plastic is polycarbonate. In one embodiment, said axially moveable member (20) further comprises one or more seals positioned around its outer circumference. In one embodiment, these seals are O-rings. In one embodiment, the seals are formed from a low-friction material, for example silicone or rubber.
In one embodiment, the system (1) further comprises a plurality of containers (40) fluidly connected to said plurality of tubes (31) whereby said chamber (10) and said plurality of containers (40) are in selective fluid communication. Said plurality of containers (40) in one embodiment comprises a container into which biological fluid has been collected. In another embodiment, said plurality of containers (40) comprises one or more containers, each for the collection of one of separated components of said biological fluid. In a further embodiment, said plurality of containers (40) comprises one or more containers containing additive solutions. Additive solutions suitable for the different components of blood, for example, are known to those of skill in the art. In a yet further embodiment, each of said plurality of containers (40) is a blood collection bag of the type widely used in the art, i.e. typically made from a biological fluid-compatible flexible plastic.
In one embodiment, the system (1) further comprises a pump (60) positioned at or around said tubing (50) between said pulse dampener (70) and said valve arrangement (30). In one embodiment, said pump is external to said tubing (50). In one embodiment, said pump (60) is a positive displacement pump. In one embodiment, said pump (60) is a peristaltic pump. In another embodiment, said pump (60) is a membrane pump.
In one embodiment of the system (1) said plurality of valves is independently a stopcock or a pinch valve. In one embodiment, each of said plurality of valves is a stopcock. In one embodiment, each of said plurality of valves is a pinch valve.
In one embodiment, the system (1) further comprises means (81) for controlling operation of the system (1). Any device onto which software can be uploaded for use can constitute such a means. In one embodiment, said means (81) comprises means (82) for monitoring the position of the axially movable member (20), to control the amount of biological fluid taken into said chamber and the expression of separated components.
In one embodiment, the system can be used for processing blood. In one embodiment, said blood is umbilical cord blood. The components of blood that are separated by use of the system when the biological fluid is blood comprise plasma, stem cells and red blood cells.
In one embodiment, the system can be used for processing biological fluids other than blood that contain one or more cell populations of interest, one non-limiting example would be a liquid cell culture.
The system of the present invention is operated generally in the same manner as described for the system of U.S. Pat. No. 6,733,433, which is incorporated herein by reference in its entirety. Therefore, for example, to process umbilical cord blood is collected into a bag containing an anticoagulant. The bag containing the collected blood is aseptically connected to axial opening of the centrifugal separating chamber. The valve in the flow path between the bag and the separation space is adjusted to open a path between the bag and the separation space, and the pump is activated to promote movement of the fluid from the bag to the separation space as well as movement of the axially moveable member towards the bottom end of the separating chamber. Centrifugation may start and be stabilised at a speed of around 4000 rpm before the blood enters the separation space. The centrifuge speed may be gradually increased to reach around 6000 rpm, which is maintained for about 5-8 min, after which the centrifuge speed is slowly decreased. Collection of the separated components can take place before the centrifuge has stopped. For collection, the valve between the umbilical cord blood collection bag and the separation space is closed and the valves between the separation space and bags for the separated components are sequentially opened at the same time as activating the pump in the opposite direction to promote movement out of the separation chamber and movement of the axially moveable member towards the top end of the separating chamber. The separated components are collected starting with plasma, followed by platelets contained in the buffy-coat layer, then stem cells, white blood cells and then red blood cells.
The different components can be identified by light absorbance in an optical line sensor, so that at a certain absorbances defined by the software the correct valves are opened to permit the components to be directed to designated bags. Centrifugation is generally stopped following collection of the stem cells and white blood cells to allow a smooth extraction of the remaining red cells into their bag. Optionally, an additive solution can be added to one or more of the bags containing the separated components by opening the appropriate valves to establish flow between a bag containing said additive solution and the selected bag. An example of an additive solution is a preservative solution based on 10 or 20 vol % DMSO, which can contain also a physiological buffer such as phosphate buffer.
Another alternative to isolate the stem cell rich fraction from the buffy-coat is by using density gradient products such as those available under the names Ficoll™ and Percoll™. The density gradient product is first introduced into the separation space, followed by introduction of the cord blood, components of the blood are separated into its respective container and its collection is completed when the density gradient appears. Possibly the density gradient product may be introduced during processing. Using Ficoll™ would for example consist of first introducing the density gradient into the processing chamber, followed then by blood. After complete introduction of blood into the chamber, a sedimentation period of a few minutes is started. Stem cells and platelets form an interface in front of the gradient, whereas erythrocytes and granulocytes pass through the Ficoll™ and are held against the walls of the separation chamber. The piston is then lifted gently as in the standard procedure, the stem cell fraction being collected at the apparition of the first platelets. The effluent line clears up again when Ficoll™ exits the chamber.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. All patents and patent applications mentioned in the text are hereby incorporated by reference in their entireties, as if they were individually incorporated.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1713252.3 | Aug 2017 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/072072 | 8/14/2018 | WO | 00 |
