Patent Application
20240085306
The present invention relates to a method for obtaining a sample enriched with cells or cell nuclei of interest from a piece of tissue, a method for analyzing biomarkers with the sample obtained by said method, as well as a kit, a system and a program for use in implementing these methods.
In recent years, a very large number of biomarkers have been used in various diagnostic purposes, and one of the major specimens for use in analysis of the biomarkers is tissues obtained from a subject. In particular, FFPE tissue sections have been used over the world in the immunohistochemistry (IHC), and recently, components of interest such as DNA have been extracted from the tissue sections for use in various analysis.
On the other hand, one of the problems in extracting a component of interest from a piece of tissue for analysis is that the collected tissue is not always abundant in cells or markers of interest and may not allow us to detect a target marker at a sufficient detection sensitivity or detection rate. For example, a polynucleotide such as DNA has been extracted from a FFPE tissue section and used for quantitative analysis of cancer-related genes, and it has been recommended that the tissue section contains 20% or more of tumor cells as a condition for performing appropriate analysis (Non-Patent Literature). However, meeting such a condition is not always easy from a practical point of view.
Therefore, in case of analyzing various biomarkers with samples prepared from tissue, it will be convenient if a sample enriched with cells or markers of interest can be obtained easily and reliably.
In view of the aforementioned needs, the present invention provides a method for obtaining a sample enriched with cells or cell nuclei of interest from a piece of tissue. The present invention also provides a method for analyzing biomarkers at an improved detection rate with the sample obtained by the above method. The present invention further provides a kit, an apparatus and a program for use in implementing these methods.
To achieve the aforementioned objects, the present inventors took an approach of crushing a collected piece of tissue to cellular level to obtain a population of particles including cells or cell nuclei, and sorting or fractionating to concentrate cells or cell nuclei of interest from the obtained population of particles. As a result of studying various conditions for pretreatment of crushing tissue, the present inventors have found that crushing the tissue through specific pretreatment is necessary for sorting or fractionating cells or cell nuclei of interest. It has also been found that cells obtained through specific pretreatment under particular conditions can be used to sort or fractionate certain cells of interest from other cells based on the optical or physical characteristics of the cells or cell nuclei of interest without using biomarkers. The present invention is based on these findings, and provides the following method, kid, apparatus and program.
[1] A method for obtaining a sample enriched with cells or cell nuclei of interest from a piece of tissue, the method comprising:
[2] The method according to [1], wherein the pretreatment further comprises treatment with a hydrolase which does not degrade a protein necessary for maintaining cell nuclear morphology.
[3] The method according to [2], wherein the hydrolase is an enzyme which does not degrade lamin.
[4] The method according to [2] or [3], wherein the hydrolase is thrombin, proline endopeptidase or hyaluronidase.
[5] The method according to any one of [1] to [4], wherein the water-flow crushing is performed by rotating a crushing member at a speed of 6,000 to 13,000 rpm.
[6] The method according to any one of [1] to [5], wherein the ultrasonic crushing is performed with an amplitude of 20 to 40%.
[7] The method according to [6], wherein the ultrasonic crushing is performed for 30 seconds to 3 minutes.
[8] The method according to any one of [1] to [7], wherein the cells of interest are tumor cells, lymphocytes, or normal cells derived from a non-cancerous part of tissue.
[9] The method according to any one of [1] to [8], wherein the piece of tissue is fixed with a fixing agent.
[10] The method according to [9], wherein the fixed piece of tissue is embedded in an embedding agent.
[11] The method according to [10], wherein before the pretreatment, the embedding agent is removed from the piece of tissue, and the piece of tissue is hydrophilized.
[12] The method according to any one of [9] to [11], wherein before the pretreatment, a crosslinked structure formed by the fixation is destroyed by heat treatment.
[13] The method according to any one of [11] to [12], wherein the population of particles obtained through the pretreatment is analyzed by flow cytometry to sort or fractionate a population of particles abundant in the cells or cell nuclei of interest based on forward scatter (FSC) intensity and/or side scatter (SSC) intensity in a scattergram obtained by said analysis.
[14] The method according to [13], wherein
[15] The method according to [13], wherein
[16] The method according to [15], wherein a region composed of a population of particles having particle sizes of 10 μm or more, 95% or more of which have particle sizes of 11 μm to 20 μm, is selected to sort or fractionate a population of particles enriched with particles derived from tumor cells.
[17] The method according to [15], wherein a region composed of a population of particles having a particle size of 8 μm or less, 95% or more of which have a particle size of 4 μm to 7 μm, is selected to sort or fractionate a population of particles enriched with particles derived from lymphocytes.
[18] A method for analyzing a biomarker present in cells or cell nuclei of interest using a sample enriched with cells and cell nuclei obtained by the method according to any one of [1] to [17].
[19] The method according to [18], wherein the cells of interest are tumor cells.
[20] The method according to [18] or [19], wherein the biomarker is a polynucleotide. a nuclear protein, a nuclear membrane protein or a cytoskeletal protein.
[21] The method according to [20], wherein the polynucleotide comprises a cancer-related gene, and the nuclear protein comprises a transcription factor or a cell cycle-related protein.
[22] A method of determining a DNA index, comprising:
DNA index=amount of DNA at largest number of particles in tumor cell nucleus-enriched sample/amount of DNA at largest number of particles in tumor cell nucleus-non-enriched sample or normal cell sample.
[23] A kit for preparing a sample enriched with cells of interest or cell nuclei thereof from a piece of tissue, the kit comprising:
[24] A kit for preparing a sample enriched with cells of interest or cell nuclei thereof from a piece of tissue, and analyzing a biomarker present in the cells or cell nuclei thereof using the sample, the kit comprising:
[25] The method according to [23] or [24], wherein the hydrolase is thrombin and/or hyaluronidase.
[26] The method according to [24] or [25], wherein the biomarker is a polynucleotide, a nuclear protein, a nuclear membrane protein or a cytoskeletal protein.
[27] A system for obtaining a sample enriched with cells of interest or cell nuclei thereof from a piece of tissue, wherein the system performs the steps of:
[28] A system for obtaining a sample enriched with cells of interest or cell nuclei thereof from a piece of tissue, wherein the system performs the steps of:
[29] The system according to [28], wherein a population of particles in a region composed of a population of particles having particle sizes of 10 μm or more, 95% or more of which have particle sizes of 11 μm to 20 μm, is sorted or fractionated to concentrate tumor cells or nuclei thereof.
[30] The system according to [28], wherein a population of particles in a region composed of a population of particles having particle sizes of 8 μm or less, 95% or more of which have particle sizes of 4 μm to 7 μm, is sorted or fractionated, to concentrate nuclei of lymphocytes.
[31] A program of instructing a flow cytometry system to perform a process for obtaining a sample enriched with cells of interest or cell nuclei thereof from apiece of tissue, wherein the program instructs the flow cytometry system to performs the steps of:
[32] A program for instructing a flow cytometry system to perform a process for obtaining a sample enriched with cells or cell nuclei thereof of interest from a tissue section, wherein the program causes the flow cytometry system to perform the steps of:
[33] The program according to [32], wherein a population of particles in a region composed of a population of particles having particle sizes of 10 μm or more, 95% or more of which have particle sizes of 11 μm to 20 μm, is sorted or fractionated to concentrate nuclei of tumor cells.
[34] The method according to [32], wherein a population of particles in a region composed of a population of particles having particle sizes of 8 μm or less, 95% or more of which have particle sizes of 4 μm to 7 μm, is sorted or fractionated to concentrate nuclei of lymphocytes.
[35] A system for obtaining a sample enriched with cells of interest or cell nuclei thereof from a piece of tissue, wherein the system performs the steps of:
[36] A program of instructing an apparatus to execute a process for obtaining a sample enriched with cells of interest or cell nuclei thereof from a piece of tissue,
The method of the present invention can concentrate biomarkers present in cells or cell nuclei of interest, thereby improving the detection rate of a biomarker of interest. In particular, the method allows even a piece of tissue with a low proportion of tumor to be used and is expected to contribute to a more precise cancer gene panel diagnosis and a novel cancer classification. The method of the present invention also allows cells or nuclei of normal tissue, and lymphocytes or nuclei thereof to be separated or isolated. For example, a tumor tissue-infiltrating lymphocytes (TIL) may serve as a predictive factor for prognosis of breast cancer, and therefore if a sample enriched with lymphocytic nuclei as well as a sample enriched with cancer cell nuclei can be fractionated from tissue from a subject, the samples providing analytical advantages, leading to clinical usefulness. The involvement of cells other than tumor cells in a local tumor microenvironment and immune response has been being researched, and these samples are also expected to be useful in this field (Non-Patent Document 5).
The present invention relates to a method for obtaining a sample enriched with cells or cell nuclei of interest, a method for analyzing biomarkers with the sample obtained by the above method, as well as a kit, a system and a program for use in implementing these methods. Embodiments thereof will be described in detail below, but the present invention is not limited to the embodiments described below.
1. Method for Preparing Sample Enriched with Cells or Cell Nuclei of Interest
In one embodiment, the present invention provides a method comprising subjecting a piece of tissue to particular pretreatment to obtain individually separated cells or cell nuclei, and sorting or fractionating a population of particles enriched with cells or cell nuclei of interest based on optical characteristics or physical characteristics of the cell nuclei.
The “piece of tissue” is usually obtained by biopsy, which involves removing a piece of tissue from a subject with a scalpel or needle. Examples of the biopsy include excision biopsy (entire removal), incision biopsy (partial removal), core biopsy (removal of a part of tissue with a large-bore needle) and fine needle aspiration (FNA) biopsy (removal of a part of tissue or a body fluid with a fine needle).
A subject may be a mammal or another animal species. The mammal is typically a human being but may be a non-human mammal. Tissue may be collected from any organs of a subject. Tissue is often collected from pathological sites, but in some cases, it is collected from normal sites, such as non-tumor tissue and lymph nodes.
The pathological sites typically include, but not being limited to, sites infiltrated with malignant tumor cells. Even when tissue is collected from a site infiltrated with malignant tumor cells, the tissue contains non-cancerous cells (e.g., normal cells, and lymphocytes). In particular, a collected tissue may contain a very small malignant tumor tissue, and therefore a large number of other cells such as normal cells. Thus, a collected tissue is usually not composed of only one type of cells.
Malignant tumors are tumors that infiltrate into surrounding tissues or metastasize, among cell populations (benign tumors and malignant tumors) that proliferate in an autonomous and uncontrollable manner due to genetic mutations. In pathology, the term “malignant tumor” is classified into:
Examples of the carcinomas include head and neck cancers (upper jaw cancer, (upper, middle and lower) pharyngeal cancers, laryngeal cancer, tongue cancer and thyroid cancer), thoracic or chest cancers (breast cancer, lung cancers (non-small cell lung cancer and small cell lung cancer)), digestive organ cancers (esophagus cancer, stomach cancer, duodenal cancer, bowel cancers (colon cancer and rectal cancer), liver cancers (liver cell cancer and bile duct cell cancer), gallbladder cancer, bile duct cancer, pancreas cancer, anus cancer, urinary organ cancers (kidney cancer, ureter cancer, bladder cancer, prostate cancer, penis cancer and testicle (testis) cancer), genital cancers (uterus cancers (uterine cervical cancer and uterine body cancer), ovary cancer, vulva cancer and vaginal cancer), and skin cancers (basal cell cancer and squamous cell cancer). Examples of the sarcoma include osteosarcoma, chondrosarcoma, and Ewing's sarcoma.
The “piece of tissue” may be enzymatically treated by the method of the present invention immediately after collection but is usually cryopreserved or fixed to be suitable for preservation for a certain period of time.
The temperature for “cryopreservation” is usually freezing at −80° C. or lower.
The “fixation” is a process of stabilizing cell morphology and tissue structure by immersing a sample in a fixing solution to cause molecular cross-linking and protein insolubilization. A known method may be used for the fixation, and examples of the method include treatments with a formalin solution, a para-formaldehyde solution, a glutaraldehyde solution, an osmium tetroxide solution, alcohol acetate, methanol, ethanol, acetone or the like. In particular, formalin fixation has been widely used as a method for fixing a pathological tissue, and use of a formalin-fixed tissue is therefore convenient in the method of the present invention.
When a fixed tissue is used, the tissue is usually embedded in an embedding agent to impart a uniform hardness to a piece of tissue (mass), and fill hollow parts in the tissue, thereby imparting a strength suitable for slicing, as well as enhance preservability. Examples of the embedding agent include, but not being limited to, paraffin, paraffin derivatives, celloidin, carbowax, agarose, non-heparin-treated serum, collagen, cellulose derivatives, chitin derivatives, chitosan derivatives and mixtures thereof. In particular, paraffin has been widely used, and formalin-fixed paraffin-embedded sections (FFPE sections) are tissue sections which have been most commonly used in pathological diagnosis. In the present invention, use of such a tissue section is convenient, accordingly.
In the method of the present invention, a piece of tissue may be preferably sliced or finely cut for efficiently obtaining a single cell or cell nucleus separated from other cells with pretreatment described later. For example, in the case of slicing, a frozen tissue or an embedded tissue can be sliced to an appropriate thickness with a microtome. A section with a thickness of 60 μm or less is convenient because pretreatment can be efficiently performed, and the section can be used for detection of various markers by the immunohistochemistry (IHC) technique. As for the thickness of tissue sections, 60 μm or less is convenient for efficient pretreatment and for use of sections in detection of various markers by immunohistochemistry (IHC), and 20 μm or less is more preferable. The number and the thickness of tissue sections may be adjusted dependent on the size of a tissue to be sliced, and the number of cells or cell nuclei required for marker analysis.
When the method of the present invention is carried out with a tissue embedded in an embedding agent, it is preferable that the embedding agent (e.g., paraffin) be removed from the embedded tissue preferably after slicing or finely cutting (de-embedding), and that the organic solvent used for the removal of the embedding agent be replaced by an aqueous solvent (hydrophilization). The embedding agent can be removed by immersing the section in an organic solvent, such as xylene. The de-embedded tissue section can also be hydrophilized by immersing the tissue section in multiple concentrations of ethanol solutions with a concentration gradient in order from higher to lower concentrations. Examples of the ethanol concentration gradient include, but not being limited to, 100%→95%→90%→70%→50%. For frozen sections which are not embedded, de-embedding and hydrophilization are not required.
When a fixed tissue is used, it is preferable to perform heat treatment to destroy a crosslinked structure formed by fixation. In the fixed tissue, a crosslinked structure is formed between peptides, which makes it difficult to access a biomarker of interest and also make it difficult for an enzyme to act on a targeted component during enzymatic treatment. The heat treatment cleaves the formed crosslinked structured, facilitating access to a biomarker and enabling efficient degradation of the tissue by enzymatic treatment.
Heat treatment is preferably performed by immersing the tissue in a solution containing a citric acid buffer solution, a surfactant, a chelating agent and/or a reducing agent. A solution containing such components is not particularly limited but includes Histo VT One (nacalai tesque), Antigen Activation Solution pH 9 (Nichirei Bioscience Inc.) and ImmunoSaver (Nisshin EM Co., Ltd.) which are commercially available as antigen retrieval agents with heating. The treatment may be performed according to the accompanying instructions, but the heating temperature may be 90° C. to 100° C., and the treatment time may be 20 to 60 minutes.
In a preferred embodiment of the present invention, tissue can be treated with a hydrolase which does not degrade a protein necessary to retain cell nuclear morphology prior to water flow crushing and/or ultrasonic crushing described below.
As used herein, the terms “cell nuclear morphology” and “cell nuclei morphology” relate to a size, a shape and a structure of a cell nuclear or cell nuclei. The wording “protein necessary for maintaining cell nuclear (nuclei) morphology” means a protein the degradation of which changes cell nuclear (nuclei) morphology, and examples thereof include lamins such as lamin A, lamin B1, lamin B2 and lamin C. Whether cell nuclear morphology has been changed or not can be determined from optical characteristics or physical characteristics of cell nuclei described later. Preferably, enzymes for use in the present invention do not degrade such proteins.
Hydrolases with such properties can be found from known databases (e.g., http://web.expasy.org/peptide_cutter/). Whether an enzyme has such properties or not can be confirmed by treating a “protein necessary for maintaining cell nuclear morphology” with the enzyme, and then determining whether the protein is cleaved with a known method, such as agarose gel electrophoresis.
Examples of the hydrolase “which does not degrade a protein necessary for maintaining cell nuclear morphology” include thrombin, proline endopeptidase, enterokinase, granzyme B, and hyaluronidase. On the other hand, hydrolases that affect cell nuclear morphology, such as pepsin, trypsin, collagenase and dispase, are not used.
Of the aforementioned enzymes, thrombin, proline endopeptidase and hyaluronidase are preferable, and thrombin and hyaluronidase are more preferable.
The “enzymatic treatment” can be performed by, for example, dissolving an enzyme in a buffer solution adjusted to an appropriated pH, immersing a piece of tissue in the solution, stirring the mixture for a predetermined time at a temperature suitable for an enzyme reaction to allow a hydrolytic reaction to occur, and then quenching the reaction as necessary.
As the buffer solution, a tris(hydroxymethyl)aminomethane buffer solution, a phosphate buffer solution, a carbonate buffer solution, a glycine buffer solution, an acetate buffer solution, a tartrate buffer solution, a citrate buffer solution, a triethanol amine buffer solution, a borate buffer solution, and a Good buffer solution may be used. It is preferable to use a buffer solution to which a surfactant is added because a surfactant promotes disruption of cell membranes. The surfactant is not particularly limited as long as it has no effect on cell nuclei, and examples thereof include anionic surfactants (carboxylic acid type, sulfonic acid type, sulfuric acid ester type, phosphoric acid ester type and the like), cationic surfactants (quaternary ammonium salt type, alkylamine salt type, pyridine ring-containing type and the like), ampholytic surfactants (betaine type, sulfobetaine type, amine oxide type, alkylimidazole type, amino acid type and the like), and nonionic surfactants (ester type, ether type, ester ether type, alkanolamide type, alkyl glycoside type and the like). The surfactant may be preferably a nonionic surfactant, which includes TritonX-100, TritonX-405, NP-40, Briji-35, Briji-58, Tween-20, Tween-80, BPSH-25, Octyl Glucoside and Octylthio Glucoside. The pH may be adjusted dependent on an enzyme used, and an optimum pH for each enzyme is well known in the art. The temperature may also be determined dependent on an enzyme used. In many cases, the temperature is in the range of 20° C. to 40° C. The reaction time may be appropriately determined dependent on the size of a tissue and the like. The reaction may be quenched by removing reagents, changing the temperature, adding a chelator, or the like, and specific procedures are well known in the art.
In the method of the present invention, tissue or an enzymatically treated product is subjected to water-flow crushing and/or ultrasonic crushing instead of the enzymatic treatment or after the enzymatic treatment. In particular, from the viewpoint of obtaining more single cells from the tissue while maintaining the morphology of the cell nuclei. “crushing with a water flow” is preferable, and it is particularly preferable to perform “crushing with a water flow” and “crushing by ultrasonication” in this order.
The term “crushing with a water flow” or “water-flow crushing” means that a tissue or, in some case, cells are crushed with a shear force from a water flow. The condition for “water-flow crushing” is that tissue can be broken down to the level of a single cell, while the morphology of the cell nucleus is not affected. In this respect, the conditions in which a rotary blade rotates at 6,000 rpm to 13,000 rpm are preferable, and the conditions in which a rotary blade rotates at 7,000 rpm to 13,000 rpm are more preferable. The treatment time may be usually 30 seconds to 3 minutes, but preferably 45 seconds to 2 minutes, and particularly preferably 1 minute. When using a water-flow crushing apparatus, the clearance between an inner blade and an outer blade may be usually 0.01 mm to 1.00 mm, but is preferably 0.02 mm to 0.50 mm, more preferably 0.03 mm to 0.30 mm.
For water-flow crushing, commercially available apparatuses may be used, such as a water flow shear apparatus (RP-10) from Sysmex Corporation, and a homogenizer (T10) from IKA. Preferably, water-flow crushing is performed in an ice-cooled environment.
The term “crushing with ultrasonication” or “ultrasonic crushing” means that a tissue or, in some case, cells are crushed with a shear force from ultrasonication. The conditions for “ultrasonic crushing” are also that tissue can be broken down to the level of a single cell, while the morphology of the cell nucleus is not affected. In this respect, the output intensity is preferably 20 to 40% in terms of an amplitude, more preferably 20 to 30% in terms of an amplitude, particularly preferably 20% in terms of an amplitude.
From the same viewpoint, the treatment time may be usually 30 seconds to 3 minutes, but preferably 45 seconds to 2 minutes, and particularly preferably 1 minute.
For ultrasonic crushing, commercially available apparatuses may be used, such as an ultrasonic crushing apparatus (VCX130PB) from SONICS&MATERIALS. Preferably, ultrasonic crushing is performed in an ice-cooled environment.
Accordingly, a preferred embodiment of the present invention provides a process comprising the following steps:
As described above, the method of the present invention provides individually separated cells or cell nuclei from tissue by shear stress of water-flow crushing and/or ultrasonic crushing, optionally following heat treatment and enzymatic treatment.
As used herein, the term “individually separated cells or cell nuclei” refers to single cells or cell nuclei present in isolation from other cells. As used in the context of “cells or cell nuclei” after enzymatic treatment, the term “cells or cell nuclei” includes not only intact cells and cell nuclei with no other cellular structures, but also cells (particles) of which part of cellular structures are destroyed, cleaved or lost as long as the cell nuclei morphology is maintained. For example, cells (particles) in which the cell membrane is destroyed or lost, but the cytoskeleton or all or part of proteins constituting the cytoskeleton is maintained, also fall within the term “cells or cell nuclei”.
In the method of the present invention, a treated product including “individually separated cells or cell nuclei” obtained through the aforementioned pretreatment is used to sort or fractionate a population of particles significantly abundant in cells or cell nuclei of interest.
The term “cells or cell nuclei of interest” means cells or cell nuclei intended to be enriched or concentrated by the method of the present invention. The term “significantly abundant” means that the proportion of cells or cell nuclei of interest is the highest among all cells or cell nuclei and other particulate substances.
In the method of the present invention, as described above, a population of particles including the “cells or cell nuclei of interest” is obtained without affecting the morphology of the cell nuclei through the treatment of obtaining single level cells or cell nuclei from tissue. In the present invention, therefore, optical characteristics or physical characteristics reflecting the maintained morphology of cell nuclei, i.e., size, shape and/or structure, including density, specific gravity, particle size and staining, are measured, and “a population of particles significantly abundant in cells or cell nuclei of interest is sorted or fractionated” based on a difference in the above characteristics between “cells or cell nuclei of interest” and the other particles. Therefore, in an embodiment of the method of the present invention, “cells or cell nuclei of interest” are concentrated without using biomarkers specifically expressed in a particular cell type.
It should be noted that as demonstrated in Examples below, the aforementioned pretreatment employed in the present invention makes it possible to “sort or fractionate a population of particles significantly abundant in cells or cell nuclei of interest” using optical characteristics or physical characteristics.
In an embodiment involving analysis of optical characteristics, a treated product after the pretreatment is optically analyzed, if necessary, after components in cell nuclei, typically nucleic acids, are visualized, for example, by staining, and a population of particles significantly abundant in cells or cell nuclei of interest is sorted or fractionated based on a difference in optical characteristics between the cell nuclei of interest and the other particles.
Examples of the optical analysis include flow cytometry, imaging cytometry, and image analysis on microscopic images.
For analysis by flow cytometry, for example, a treated product after pretreatment is subjected to fluorescent staining of cell nuclei if necessary, and then subjected to flow cytometry, and based on the obtained forward scatter light (FSC) intensity, side scatter light (SSC) intensity and/or fluorescent intensity, a population of particles significantly abundant in “cells or cell nuclei of interest” is sorted from other cells or cell nuclei or other particles by gating. The forward scatter light (FSC) intensity is an index of the size of particles. The side scatter light (SSC) intensity is an index of the granularity and complexity of cell nuclei, where cell nuclei with high granularity like tumor cells exhibit a higher scatter light intensity. The “sorted” population of particles can be “fractionated” to a given chamber.
As used herein, the term “sort” means that data obtained by analysis is processed to select a population of particles in a specific area, but the population of particles is not required to be physically separated from other populations of particles. On the other hand, the term “fractionate” means that a population of particles including “cells or cell nuclei of interest” are obtained in a state of being physically separated from other populations of particles. The term “obtain a sample enriched with cells or cell nuclei of interest” means that a sample enriched with cells or cell nuclei of interest is obtained on data or physically by any of “sorting” and “fractionation”. The term “enriched” means that the ratio of the number of cells or cell nuclei of interest with respect to the number of all cells increases as compared to that before treatment. The term “concentration”, as used herein, has the same meaning as “enrichment”, and the terms “enrichment” and “concentration” are interchangeably used.
When “a population of particles significantly abundant in cells and cell nuclei of interest” is selected based on the forward scatter (FSC) intensity and/or the side scatter (SSC) intensity, the cells or cell nuclei of interest can be sorted or fractionated by, for example, the following procedure.
A plurality of known cell types are analyzed by flow cytometry to generate a histogram of forward scatter (FSC) intensity or side scatter (SSC) intensity and the number of particles or a scattergram of forward scatter (FSC) intensity and side scatter (SSC) intensity for cell nuclei derived from each cell type, and an area or region more abundant in nuclei of each cell type than in nuclei of other cell types is determined based on the forward scatter (FSC) intensity and/or side scatter (SSC) intensity; and
When “a population of particles significantly abundant in cells or cell nuclei of interest” is sorted based on the forward scatter (FSC) intensity, a correlation between the forward scatter (FSC) intensity and particle sizes is determined in advance, the particle size is calculated from the forward scatter (FSC) intensity obtained by analyzing a treated product after pretreatment by flow cytometry, and a population of particles with particle sizes in a particular range specific for each cell type are sorted or fractionated.
For example, standard particles having different known particle sizes are analyzed by flow cytometry, and a calibration curve is produced from the obtained forward scatter (FSC) intensity and the particle sizes of the standard substances. The treated product after the pretreatment is measured by flow cytometry, and the obtained forward scatter (FSC) intensity is applied to the calibration curve to calculate a particle size.
The calculated particle sizes are used to sort or fractionate, for example, a population of particles significantly abundant in particles having particle sizes of 10 μm or more, 95% or more of which have particle sizes of 11 μm to 20 μm to obtain a population of particles enriched with tumor cells or cell nuclei thereof.
Similarly, for example, a population of particles significantly abundant in particles having particle sizes of 8 μm or less, 95% or more of which have particle sizes of 4 μm to 7 μm, is selected to obtain a population of particles enriched with lymphocytes or cell nuclei thereof.
When “a population of particles significantly abundant in cells or cell nuclei of interest” is sorted by flow cytometry, the population of particles is sorted so that the “cells or cell nuclei of interest” account for preferably 60% or more, more preferably 70% or more, further more preferably 80% or more, even more preferably 90% or more, particularly preferably 95% or more, of the total particles.
When image cytometry is applied, a suspension liquid of the pretreated particles is subjected to fluorescent staining of cell nuclei, then placed on a multi-well plate or slide glass, and laser-scanned to obtain a fluorescent image; and cell nucleus morphology (e.g., size, perimeter, and circularity) is analyzed to sort or fractionate “cells or cell nuclei of interest” from other cells or cell nuclei based on the results of the analysis.
Alternatively, polyacrylamide electrophoresis, a filtration method, an immunoprecipitation method, a centrifugal separation method or the like can be used to fractionate “cells or cell nuclei of interest” based on a difference in particle size or specific gravity (density).
Thus, the “optical characteristics or physical characteristics of cell nuclei” can vary depending on a methodology for use in sorting or fractionation. The “optical characteristics of cell nuclei” include fluorescent intensity, visible light intensity, ultraviolet intensity, absorbance, scatter light intensity and the like, and the “physical characteristics of cell nuclei” include size, specific gravity (density) and the like. However, various characteristics may be used dependent on a methodology to be selected, and other characteristics may be utilized as long as they reflect cell nucleus morphology.
In this way, the method of the present invention enables sorting or fractionation of a population of particles more abundant in “cells or cell nuclei thereof of interest” than in other cells or cell nuclei thereof or other particles. For example, as demonstrated in Examples below, a sample enriched with tumor cells or cell nuclei thereof can be obtained by sorting or fractionating tumor cells or cell nuclei thereof, based on optical characteristics or physical characteristics reflecting the morphology of the cell nuclei, from other cells such as lymphocytes and normal cells derived from a non-cancerous part of tissue or cell nuclei thereof. Also, in case of obtaining a sample enriched with lymphocytes, lymphocytes or cell nuclei thereof are sorted or fractionated, based on optical or physical characteristics reflecting the morphology of the cell nuclei, from other cells such as tumor cells and normal cells derived from a non-cancerous part of tissue or cell nuclei thereof. A sample enriched with normal cells derived from a non-cancerous part of tissue can be obtained in a similar manner.
In another embodiment, the present invention provides a method for analyzing biomarkers present in cells or cell nuclei of interest using a sample enriched with the cells or cell nuclei obtained by the aforementioned method.
A sample obtained by the aforementioned method is enriched with cells or cell nuclei of interest, and biomarkers present in the cells or cell nuclei are contained at a high concentration in the sample. Therefore, use of the sample in examination for the biomarkers enables improvement of the detection and positive rates. As demonstrated in Examples below an improved correlation with a conventional IHC method is also expected. Even when it is necessary to examine a biomarker in a piece of tissue with few cells or cell nuclei, a sample enriched with a targeted marker can be prepared from a collected tissue to facilitate detecting the targeted marker.
Accordingly, the method for examination according to the present invention is not particularly limited in terms of biomarkers or samples, any tissue can be used as examination samples, and any biomarkers in cells or cell nuclei can be analyzed. Examples of the biomarker include, but not being limited to, polynucleotides, nuclear proteins, nuclear membrane proteins, and intracellular proteins.
Examples of the polynucleotide include genomic DNA, cDNA, and mRNA. In particular, an extremely large number of various disease-related genes have been identified in recent years, and can be subject to the method for examination according to the present invention. Examples of the disease-related gene include cancer-related genes such as ABL 1, ACVR1B, AKT1, AKT2, AKT3, ALK, ALOX12B, AMER1, APC, AR, ARAF, ARFFP1, ARD1A, ASXL1, ATM, ATR, ATRX, AURKA, AUFKB, AXIN1, AXL, BAP1, BARD1, BCL2, BCL2L1, BCL2L2, BCL6, BCOR, BCORL1, BRAF, BRCA1, BRCA2, BRD4, BRIP1, BTG1, BTG2, BTX, C11orf30, CALR, CARD11, CASP8, CBFB, CBL, CCND1, CCND2, CCND3, CCNE1, CD22, CD274, CD70, CD79A, CD79B, CDC73, CDH1, CDK12, CDK4, CDK6, CDK8, CDKN1A, CDKN1B, CDKN2A, CDKN2B, CDKN2C, CEBPA, CHEK1, CHEK2, CIC, CREBBP, CRKL, CSF1R, CSF3R, CTCF, CTNNA1, CTNNB1, CUL3, CUL4A, CXCR4, CYP17A1, DAXX, DDR1, DDR2, DIS3, DNMT3A, DOT1L, EED, EGFR, EP300, EPHA3, EPHB1, EPHB4, ERBB2(HER2), ERBB3, ERBB4, ERCC4, ERG, ERRFI1, ESR1, EZH2, FAM46C, FANCA, FANCC, FANCG, FANCL, FS, FBXW7, FGF10, FGF12, FGF14, FGF19, FGF23, FGF3, FGF4, FGF6, FGFR1, FGFR2, FGFR3, FGFR4, FH, FLCN, FLT1, FLT3, FOXL2, FUPB1, GABRA6, GATA3, GATA4, GATA6, GID4(C17orf39), GNA11, GNA13, GNAQ, GNAS, GRM3, GSK3B, H3F3A, HDAC1, HGF, HNF1A, HRAS, HSD3B1, ID3, IDH1, IDH2, IGF1R, IKBKE, IKZF1, INPP4B, IRF2, IRF4, IRS2, JAK1, JAK2, JAK3, JUN, KDM5A, KDM5C, KDM6A, KDR, KEAP1, KEL, KIT, KIHL6, KMT2A(MLL)KMT2D(MLL2), KRAS, LTK, LYN, MAF, MAP2K1, MAP2K2, MAP2K4, MAP3K1, MAP3K13, MAPK1, MCL1, MDM2, MDM4, MED12, MEF2B, MEN1, MERTK, MET, MITF, MKNK1MLH1, MPL, MRE11A, MSH2, MSH3, MSH6, MAT1R, MAp, MTOR, MUTYH, MYC, MYCL, MYCN, MYD88, NBN, NF1, NF2, NFE2L2, NFKB1A, NKX2-1, NOTCH1, NOTCH2, NOTCH3, NPM1, NRAS, NT5C2, NTRK1, NTRK2, NTRK3, P2RY8, PALB2, PARK2, PARP1, PARP2, PARP3, PAX5, PBRM1, PDCD1, PDCD1L G2, PDGFRA, PDGFRB, PDK1, PIK3C2B, PIK3C2G, PIK3CA, PIK3CB, PIK3R1, PIM1, PMS2, POLD1, POLE, PPARG, PPP2R1A, PPP2R2A, PPDM1, PRKAR1A, PRKCI, PTCH1, PTEN, PTPN11, PTPRO, qKI, RAC1, RAD21, RAD51, RAD51B, RAD51C, RAD51D, RAD52, RAD54L, RAF1, RARA, RB1, RBM10, RE1, RET, RICTOR, RNF43, ROS1, RPTOR, SDHB, SDHC, SDHD, SETD2, SF3B1, SGK1, SMAD2, SMAD4, SMARC A4, SMARC B1, SMO, SNCAIP, SOCS1, SOX2, SOX9, SPEN, SPOP, SRC, STAG2, STAT3, STK11, SUFU, SYK, TBX3, TEK, TET2, TGFBR2, TIPARP, TNFAIP3, TNFRSF14, TP53, TSC1, TSC2, TYRO3, U2AF1, VEGFA, VHL, WHSC1, WHSC1L1, WT1, XPO1, WRCC2, ZNF217, and ZNF703.
Examples of the nuclear protein include transcription factors, and cell cycle-related proteins.
Examples of the transcription factors include, but not being limited to, homeodomains, bHLH, bZIP. Forkhead, nuclear receptors, HMG/Sox, Ets, T-Box, AT hook, POU, Myb/SANT, THAP finger, CENPB, E2F, BED ZF, GATA, Rel, CxcC, IRF, SAND, SMAD, HSF, MBD, RFX, CUT, DM, STAT, ARID/BRIGHT, Grainylhead, MADS box, Ap-2, CSD, and PAX. Examples of the cell cycle-related proteins include, but not being limited to, Ki-67, CDK (CDK1 to CDK20 are known as subtypes), Cyclin A, Cyclin B, WEE1, MYT1, CDC25B, CDC25C, ATM, ATR, CHK1, CHK2, MRE11, RAD50, NBS1, ATRIP, RAD9, RAD1, HUS1, MDC1, TopBP1, Claspin, Timeless, Tipin, Plk1-4, Aurora A/B, CDC20, CCH1, MAD1, MAD2, BUBR1, BUB1, BUB3, MST1/2, LATS1/2, MOB1A,B, and CDC14.
Examples of the nuclear membrane proteins include, but not being limited to, estrogen receptors, progesterone receptors.
Examples of the intracellular protein include, but not being limited to, factors involved in signal transduction, and cytoplasmic skeletal proteins. Examples of the factor involved in signaling include, but not being limited to, PTEN, PI3K, Akt, SRC, Ras, Raf, ERK, MEK, Myc, mTORC1/2, S6K, JAK, STAT, p53, SMAD, and JNK. Examples of the cytoplasmic skeletal proteins include, but not being limited to, cytokeratin, and vimentin.
Biomarkers may be measured by known methods applicable to individual biomarkers. However, in the case where cells or cell nuclei of interest have been sorted by an optical analysis method such as cytometry, biomarkers of interest may be labeled after the pretreatment in advance, then a population significantly abundant in cells or cell nuclei of interest is sorted by the aforementioned method, and the sorted population is continuously analyzed for the labeled biomarkers using the same analyzer.
For example, after the pretreatment, a biomarker of interest in the pretreated product can be directly labeled with a labeling substance. Alternatively, a ligand that specifically binds to a biomarker of interest, such as an antibody or a nucleic acid probe, or a secondary ligand that specifically binds to the above ligand is labeled with a labeling substance, the first ligand is allowed to be bound to the biomarker of interest in the pretreated product, optionally the secondary ligand is bound to the first one, and/or the cell nuclei are stained. The treated product is analyzed by cytometry, a population significantly abundant in cells or cell nuclei of interest is sorted, and the sorted population is analyzed for the labeled biomarkers.
Examples of the labeling substance include avidin-biotin complexes (ABC), fluorescent compounds, enzymes, and chemiluminescent substances.
The fluorescent compounds are not particularly limited, but examples thereof include cyanine-based dyes such as Cy3, fluorescein isothiocyanate (FITC), allophycocyanin and rhodamine. When a plurality of biomarkers are analyzed, ligands (antibodies or secondary antibodies thereto, nucleic acid probes which hybridize with targeted polynucleotides, and the like) can be labeled with a plurality of fluorescent substances which emit light with different fluorescence wavelengths. For this purpose, fluorescent substances such as Alexa Fluor (registered trademark) series can be used.
The labeling enzymes are not particularly limited, but examples thereof include alkali phosphatase and horseradish peroxidase.
The chemiluminescent substances are not particularly limited, but examples thereof include luminol, AMPPD (registered trademark), CSPD (registered trademark) and CDP-Star (registered trademark).
Examples of compounds for staining cell nuclei include fluorescent substances such as DAPI and propidium iodide (PI).
In one embodiment, when a population of cells in a tissue section may have a plurality of targeted biomarkers,
After a sample containing cells or cell nuclei of interest is fractionated, alternatively, an organelle (e.g., nucleic acid) having a targeted biomarker may be extracted by a known method from the fractionated sample and used in analysis. Even in this process, the fractionated sample is enriched with targeted biomarkers, which may contribute to an improved detection rate and the like.
One embodiment of the present invention provides a method for analyzing DNA aneuploidy with a sample obtained by the aforementioned method for obtaining a sample enriched with tumor cells or cell nuclei thereof without using biomarkers (specific to cell types).
Herein, the term “DNA aneuploidy” means abnormal cells different in amount of DNA in cell nuclei from normal cells, and the DNA aneuploidy can be evaluated by a DNA index expressed as a numerical value obtained by dividing the amount of DNA (indicated by, for example, amount of fluorescence of DAPI-A) at the most population of cells (usually, a population of G0/1 cells) in a specimen by the amount of DNA at the most population of G0/1 cells in normal diploid cells.
Specifically, the aforementioned method, preferably the method comprising the step of fractionating or sorting a population of particles significantly abundant in tumor cells or cell nuclei thereof from a tissue by flow cytometry provides a sample enriched with tumor cells or cell nuclei thereof (tumor cell nucleus-enriched sample); whereas a sample which is not enriched with tumor cells or cell nuclei thereof (tumor cell nuclei-non-enriched sample or normal cell sample) is obtained from the same tissue or a normal tissue (e.g., if the proportion of tumor cells is high) in the same manner except that fractionation or sorting of a population of particles significantly abundant in tumor cells or cell nuclei thereof is not performed. A histogram of the number of particles and the amount of DNA (indicated by, for example, amount of fluorescence of DAPI-A) is generated for each of the samples, the amount of DNA at the largest number of particles is identified, and the DNA index is determined by the following equation, whereby the DNA aneuploidy can be evaluated:
DNA index=amount of DNA at largest number of particles in tumor cell nucleus-enriched sample/amount of DNA at largest number of particles in tumor cell nucleus-non-enriched sample or normal cell sample.
Conventionally, for example, a scattergram with the fluorescence intensity of cytokeratin in the horizontal axis and the fluorescence intensity of vimentin in the vertical axis is developed, a cytokeratin-positive and vimentin-negative region is gated as a cancer cell region, a cytokeratin-negative and vimentin-positive region is gated as an interstitial cell region, the most frequent value of DAPI-A fluorescence is determined for each of the gated populations, and the ratio of the most frequent value of the cancer cell region to the most frequent value of the interstitial cell region is calculated to determine a DNA index (Non-Patent Literature 6). However, according to the aforementioned embodiment of the present invention, the DNA index can be determined without relying on such a biomarker. This provides an advantage that it can be applied to a case in which a biomarker is deficient (e.g., cytokeratin-negative breast cancer) and a population of cancer cells that have undergone epithelial-mesenchymal transition, whereby vimentin is positive. As described later, the method according to the embodiment of the present invention has been confirmed to have a high correlation with a conventional method for determining the DNA index with a biomarker.
In another embodiment, the present invention provides a kit for preparing a sample containing concentrated cells of interest or cell nuclei thereof from a piece of tissue. The kit comprises a hydrolase which does not degrade a protein necessary for retaining or maintaining cell nuclear morphology but can degrade at least one of components of the extracellular matrix or cell membrane proteins involved in intercellular adhesion.
The hydrolase in the kit is the same as described for the method for preparing a sample enriched with cells or cell nuclei thereof of interest from a piece of tissue, and examples thereof include thrombin, proline endopeptidase and hyaluronidase, with thrombin and/or hyaluronidase being particularly preferable.
The hydrolase may be in a dried solid state, or in a state of being dissolved in a buffer solution. When the hydrolase is in a solid state, the kit may contain a solution used to dissolve the enzyme.
To facilitate crushing of the tissue with a shear force, the kit may contain a buffer solution for immersing or dispersing an enzyme-treated product during crushing. Preferably, the buffer solution contains a surfactant. As the surfactant, CHAPS, NP-40 and Triton-X100 are preferable, and NP-40 and Triton-X100 are more preferable.
When fixed tissue is used, the kit may contain a solution for heating treatment. The solution for heating treatment is preferably a solution containing a citrate buffer solution, a surfactant, a chelating agent, and/or a reducing agent.
When embedded tissue is used, the kit may contain a de-embedding agent and a hydrophilizing agent. Examples of the de-embedding agent include organic solvents such as xylene, and examples of the hydrophilizing agent include ethanol solutions with such different concentrations as to generate a concentration gradient.
In still another embodiment, the present invention provides a kit for preparing a sample enriched with cells or cell nuclei thereof of interest from a piece of tissue, and analyzing biomarkers present in the cells or cell nuclei thereof using the sample. The kit comprises the aforementioned hydrolase, optionally other components for the aforementioned pretreatment, and reagents for assay of biomarkers.
The reagents for use in assay (detection, quantitative determination or analysis) of biomarkers may be known reagents which have been used for respective biomarkers. As described above, the biomarker is not particularly limited, and examples thereof include polynucleotides, nuclear proteins, nuclear membrane proteins, and intracellular proteins. The kit usually contains a ligand (e.g., antibody or probe) binding to a targeted biomarker, or a labeling substance which visualizes a targeted biomarker. The ligand (e.g., antibody or probe) binding to a targeted biomarker or a secondary ligand binding to the first ligand is usually labeled with a labeling substance. Usually, the kit contains a nucleic acid staining compound (e.g., DAPI or propidium iodide (PI)).
In still another embodiment, the present invention provides a system for obtaining a sample enriched with cells or cell nuclei of interest from a piece of tissue. In one embodiment, the system carries out the steps of: analyzing a sample by flow cytometry to determine a region more abundant in a known cell type than in populations of cells or cell nuclei of other types; and obtaining a sample enriched with cells or cell nuclei of interest, based on the determined region, from a sample prepared by the pretreatment of tissue to be examined.
In the first step, particles containing cell nuclei obtained by subjecting a plurality of known cell types to the aforementioned pretreatment are analyzed by flow cytometry to obtain a histogram or scattergram of the forward scatter (FSC) intensity and/or the side scatter (SSC) intensity, and a region more abundant in cell nuclei of each cell type than in cell nuclei of other cell types is determined in the obtained histogram or scattergram.
In the second step, a sample prepared by subjecting a piece of the tissue to be examined to the aforementioned pretreatment is analyzed by flow cytometry to obtain a histogram or scattergram of the forward scatter (FSC) intensity and/or the side scatter (SSC) intensity, and a population of particles in the region predetermined to be more abundant in cell nuclei of cells identical in type to the cells of interest in the obtained histogram or scattergram is sorted or fractionated.
In a second embodiment, the system of the present invention carries out the steps of: preparing calibration data with a standard substance; and comparing data obtained by analyzing a test sample by flow cytometry with the calibration data to sort or fractionate a population of particles having particle sizes in a particular range.
In the first step, standard particles having known different particle sizes are analyzed by flow cytometry to produce calibration curve data of the obtained forward scatter (FSC) intensity and the particle size of the standard particles.
In the second step, a sample prepared by subjecting a piece of tissue to be examined to the aforementioned pretreatment is analyzed by flow cytometry to obtain forward scatter (FSC) intensity data, and the obtained forward scatter (FSC) intensity is compared with the calibration data to sort or fractionate a population of particles having particle sizes in a particular range.
In the second embodiment, for example, a population of particles in a region composed of a population of particles having particle sizes of 10 μm or more, 95% or more of which have particle sizes of 11 μm to 20 μm, is sorted or fractionated to obtain a sample enriched with tumor cells or nuclei thereof.
A population of particles in a region composed of a population of particles having particle sizes of 8 μm or less, 95% or more of which have particle sizes of 4 μm to 7 μm, is sorted or fractionated to obtain a sample enriched with lymphocytes or nuclei thereof.
In a third embodiment, the system of the present invention provides a system for carrying out the aforementioned process for sorting or fractionating a population of particles enriched with cells or cell nuclei of interest, as well as carrying out the step of performing the aforementioned pretreatment to obtain a population of particles including individually separated cells or cell nuclei.
In a fourth embodiment, the present invention provides a system for carrying out the aforementioned process for sorting or fractionating a population of particles enriched with cells or cell nuclei of interest, and optionally the aforementioned pretreatment, as well as carrying out analysis of a biomarker with the sample enriched with cells or cell nuclei of interest.
These systems carry out the aforementioned steps usually in accordance with a pre-defined program. Accordingly, the present invention also provides a program for instructing the system to carry out the steps.
The present invention will be described in further detail by the experiments below, but the experiments should not be construed as limiting the present invention.
Human breast cancer cells fixed with formalin were subjected to water-flow crushing, a nuclear skeletal protein was then immuno-fluorescently stained, observed with a fluorescence microscope, and analyzed by a flow cytometer to investigate effects of water-flow crushing on cell nuclear morphology.
The human breast cancer cell line MDA-MB-231 was acquired from ATCC and used in the present test.
The cells were cultured in Leibovitz's L-15 medium supplemented with 10% fetal bovine serum (FBS). After sufficient proliferation of the cells, a culture solution was drawn out, and the cells were washed with PBS, followed by adding TrypLE Express (Thermo Fisher Scientific) and recovering the cells. Further, the cells were sufficiently suspended in PBS, then dispensed at 1×106 and centrifuged, PBS was removed, a 10% formalin neutral buffer solution (Wako Pure Chemical Industries, Ltd.) was added to the cells to subject the cells to fixation at 4° C. for 24 hours. Before the cells were used, the formalin solution was removed, and the cells were washed with PBS.
Histo VT One (manufactured by nacalai tesque) diluted 10 times with pure water was added to formalin-fixed cells, which was heated on a heat block at 98° C. for 40 minutes. After heating, the cells were placed still at room temperature for 20 minutes, followed by removing the Histo VT One liquid.
The cells were crushed in 1 mL of TBS in an ice-cooled environment for 1 minute using a homogenizer (T10) from IKA-Werke GmbH & CO. The rotation speed was set to 7,100 and 12,800 rpm. The clearance between a rotary blade and a stationary blade was set to 0.1 mm as in 5G Shaft Generator.
4% BSA/TBS containing 10% normal goat serum (Wako) was added to a microtube containing the treated product obtained by water-flow crushing, and the mixture was placed still at room temperature for 30 minutes and subjected to blocking treatment. Immunofluorescent staining was performed with a mixed antibody of an anti-lamin A antibody, an anti-lamin B1 antibody and an anti-lamin C antibody (rabbit monoclonal antibodies from Abcam: Anti-Lamin A+Lamin B1+Lamin C antibodies (ab108922)) as primary antibodies, and a goat anti-rabbit IgG antibody (Goat anti-Rabbit IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 488 from Thermo Fisher Scientific) as a secondary antibody. The primary antibody reaction was carried out at 37° C. for 15 minutes, and the secondary antibody reaction was carried out at room temperature for 15 minutes. DAPI Solution (Wako) was added to stain cell nuclei 10 minutes after the addition of the secondary antibody. The reactions were carried out under a light-shielding condition after addition of the secondary antibody. 0.5% BSA/TBS was used as an antibody diluting liquid, and washing with 0.5% BSA/TBS was carried out three times between the steps. Instead of the primary antibody, a corresponding antibody identical in type to the primary antibody was used as an isotype matched control.
1-6. Observation with Fluorescence Microscope
For microscopic observation, All-in-One Fluorescence Microscope BZ-X810 (KEYENCE CORPORATION) was used. DAPI Filter (Ex 360 nm, Em 460 nm) and GFP Filter (Ex 470 nm, Em 510 nm) were used for observation. An objective lens with a magnification of 20 times was used.
The cells were caused to pass through a 35 μm filter (380 meshes, for flow cytometer) for Falcon (registered trademark) Cell Strainer 5 mL Tube, followed by measurement with a laser intensity gain value (FSC: 400, SSC: 400) using a flow cytometer (NovoCyte Quanteon Flow Cytometer from Agilent Technologies).
For analysis of the obtained measurement data, software FlowJo v 10.6.2 manufactured by Becton Dickinson and Co was used. The data was analyzed by the following procedure. A graph with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis was prepared (
As shown in fluorescence microscope images of
Recovery of Cell Nuclei from FFPE Tissue by Water-Flow Crushing
A breast cancer FFPE tissue section was deparaffinized, hydrophilized, heated, then subjected to water-flow crushing, nucleic acid was stained, and the treated product was then analyzed by a flow cytometer to evaluate effects of the rotation speed and the clearance between a rotary blade and a stationary blade in water-flow crushing on recovery of cell nuclei.
A breast cancer FFPE tissue block purchased from ProteoGenex, Inc was used.
A tissue section with a thickness of 20 μm was prepared from a FFPE block using a sliding microtome manufactured by Thermo Fisher Scientific.
1 mL of xylene was added to the FFPE section, the section was placed still for 10 minutes, and xylene was then removed. These steps were carried out again to completely remove paraffin. Subsequently, the section was exposed to 100% ethanol, 50% ethanol and deionized water in this order for 3 minutes each to hydrophilize the section.
The same procedure as in Test 1 was carried out.
The tissue after heating was crushed in 1 mL of TBS in an ice-cooled environment for 1 minute using a water flow shear apparatus (RP-10) from Sysmex Corporation and a homogenizer (T10) from IKA. The rotation speed was set to 10,000 rpm for RP-10, and 7,100, 9,100 and 12,800 rpm for T10. The clearance between a rotary blade and a stationary blade was set to 0.05 mm as in the accessory for RP-10, 0.1 mm as in 5G Shaft Generator and 0.25 mm as in 8G Shaft Generator for T10.
0.5% BSA/TBS and DAPI Solution (Wako) were added to the cells after crushing, and the cells were placed still for 5 minutes under a light-shielding condition.
The same procedure as in Test 1 was carried out.
For analysis of the obtained measurement data, software FlowJo v10.6.2 manufactured by Becton Dickinson and Co was used. The data was analyzed by the following procedure. A graph with the fluorescent intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis was prepared, and regions with 2n or more nuclear chromosomes, 2n and less than 2n (tissue debris) were each gated (
As shown in
Examination of Form of Cell Nuclei Recovered from FFPE Tissue Section by Water-Flow Crushing
The breast cancer FFPE tissue section was subjected to pretreatment including water-flow crushing, and an intranuclear skeletal protein was immuno-fluorescently stained, observed with a fluorescence microscope, and analyzed by a flow cytometer to examine effects of water-flow crushing on cell nuclear morphology.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The tissue after heating was crushed in 1 mL of TBS in an ice-cooled environment for 1 minute using a water flow shear apparatus (RP-10) from Sysmex Corporation and a homogenizer (T10) from IKA. The rotation speed was set to 10,000 rpm for RP-10, and 12,800 rpm for T10. The clearance between a rotary blade and a stationary blade was set to 0.05 mm as in the accessory for RP-10, and 0.1 mm as in 5G Shaft Generator for T10.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
As shown in
Human breast cancer cells fixed with formalin were subjected to ultrasonic crushing, an intranuclear skeletal protein was then immuno-fluorescently stained, observed with a fluorescence microscope, and analyzed by a flow cytometer to examine effects of ultrasonic crushing on cell nuclear morphology.
The human breast cancer cell line MDA-MB-231 was acquired from ATCC, and used in the present test.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
The cells were crushed in 1 mL of TBS in an ice-cooled environment for 30 seconds using an ultrasonic crushing apparatus (VCX130PB) from Sonics & Materials, Inc. The output intensity was set to 20%, 30% or 40% in terms of an amplitude.
The same procedure as in test 1 was carried out.
1-6. Observation with Fluorescence Microscope
The same procedure as in test 1 was carried out.
The same procedure as in test 1 was carried out.
The same procedure as in test 1 was carried out.
As shown in the fluorescence microscope images of
Recovery of Cell Nuclei from FFPE Tissue Section by Combination of Water-Flow Crushing and Ultrasonic Crushing
A breast cancer FFPE tissue section was deparaffinized, hydrophilized, heated, subjected to water-flow crushing and ultrasonic crushing, nucleic acid was stained, and the treated product was then analyzed by a flow cytometer to evaluate effects of the intensity of ultrasonic crushing on recovery of cell nuclei.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The tissue after heating was crushed at 10,000 rpm in 1 mL of TBS in an ice-cooled environment for 1 minute using a water flow shear apparatus (RP-10) from Sysmex Corporation. Further, using an ultrasonic crushing apparatus (VCX130PB) from Sonics & Materials, Inc. the tissue after water-flow crushing was crushed at an output intensity of 20%, 30% or 40% in terms of an amplitude in 1 mL of TBS in an ice-cooled environment for 30 seconds.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 2 was carried out.
As shown in
A breast cancer FFPE tissue section was subjected to pretreatment including water-flow crushing and ultrasonic crushing, then stained with a nucleic acid, and analyzed by a flow cytometer to evaluate effects of the ultrasonic crushing time on recovery of cell nuclei.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The tissue after heating was crushed at 10,000 rpm in 1 mL of TBS in an ice-cooled environment for 1 minute using a water flow shear apparatus (RP-10) from Sysmex Corporation. Further, using an ultrasonic crushing apparatus (VCX130PB) from Sonics & Materials, Inc, the tissue after water-flow crushing was crushed at output intensities of 20% and 30% in 1 mL of TBS in an ice-cooled environment for 1, 2 and 3 minutes.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 2 was carried out.
As shown in
From the above, it was indicated that in recovery of cell nuclei from FFPE, the increased ultrasonic crushing time was effective for crushing aggregates of 2n or more and improved recovery efficiency although the amount of tissue debris of less than 2n was increased as in the increased crushing intensity.
Examination of Form of Cell Nuclei Recovered from FFPE Tissue Section by Combination of Water-Flow Crushing and Ultrasonic Crushing
A breast cancer FFPE tissue section was subjected to pretreatment including water-flow crushing and ultrasonic crushing, and an intranuclear skeletal protein was then immuno-fluorescently stained, observed with a fluorescence microscope, and analyzed by a flow cytometer to examine effects of water-flow crushing on cell nuclear morphology.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The tissue after heating was crushed at 10,000 rpm in 1 mL of TBS in an ice-cooled environment for 1 minute using a water flow shear apparatus (RP-10) from Sysmex Corporation. Further, using an ultrasonic crushing apparatus (VCX130PB) from Sonics & Materials, Inc. the tissue after water-flow crushing was crushed at an output intensity of 20% in 1 mL of TBS in an ice-cooled environment for 1 minute.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
As shown in
Effects of Treatments with Different Enzymes on Cell Nuclei Morphology of Formalin-Fixed Cells
Formalin-fixed human breast cancer cells were treated with various enzymes, and an intranuclear skeletal protein was then immuno-fluorescently stained, observed with a fluorescence microscope, and analyzed by a flow cytometer.
The human breast cancer cell line MDA-MB-231 was acquired from ATCC, and used in the present test.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
A thrombin reagent (25 mM Tris-HCl pH 7.4, 150 mM NaCl, 1,000 KU/L thrombin, 10 mM CaCl2) was added to the cells after the heating treatment, and the cells were heated on a heat block at 37° C. for 20 minutes.
A dispase reagent (25 mM Tris-HCl pH 7.4, 150 mM NaCl, 3,000 PU/mL dispase) was added to the cells after the heating treatment, and the cells were heated on a heat block at 37° C. for 20 minutes.
A trypsin reagent (25 mM Tris-HCl pH 7.4, 150 mM NaCl, 2.5 mg/mL trypsin) was added to the cells after the heating treatment, and the cells were heated on a heat block at 37° C. for 20 minutes.
A proline endopeptidase reagent (25 mM Tris-HCl pH 7.4, 10 KU/L proline endopeptidase) was added to the cells after the heating treatment, and the cells were heated on a heat block at 37° C. for 20 minutes.
A hyaluronidase reagent (25 mM Tris-HCl pH 7.4, 150 mM NaCl, 4,000-10,000 KU/L hyaluronidase I-S. 7,500-30,000 KU/L hyaluronidase IV-S) was added to the cells after the heating treatment, and the cells were heated on a heat block at 37° C. for 20 minutes.
1-4F. Not Treated with Enzyme
A buffer solution (25 mM Tris-HCl, pH 7.4, 150 mM NaCl) was added to the cells after the heating treatment, and the cells were heated on a heat block at 37° C. for 20 minutes.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
As shown in
Effects of Enzymatic Treatment in Recovery of Cell Nuclei from FFPE Tissue Section
A breast cancer FFPE tissue section was treated with an enzyme, then subjected to pretreatment including water-flow crushing and ultrasonic crushing, and an intranuclear skeletal protein was then immuno-fluorescently stained, observed with a fluorescence microscope, and analyzed by a flow cytometer to examine effects of enzymatic treatment on cell nuclear morphology.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 8 was carried out.
The tissue after the thrombin treatment was treated in the same manner as in test 7.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 1 was carried out.
As shown in
Formalin-fixed breast cancer cells and T lymphocytes were heated, treated with thrombin, then stained with a nucleic acid, and analyzed by a flow cytometer to compare the distributions of cancer cells and lymphocytic cells.
Human breast cancer cell lines T47D, MDA-MB-231 and SKBr3 and the human T lymphocytic cell line Jurkat were acquired from ATCC, and used in the present test.
The human breast cancer cell lines T47D, MDA-MB-231 and SKBr3 were cultured, respectively, in RPMI-1640 medium, Leibovitz's L-15 medium and McCoy's 5A medium each supplemented with 10% FBS. The Jurkat cell line was cultured in RPMI-1640 medium supplemented with 10% FBS. After sufficient proliferation of the cells, the cells were recovered, and fixed with formalin as in Test 1.
The same procedure as in Test 1 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
As in Test 1, on a graph with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis, a region of 2n or more nuclear chromosomes was gated as cells, and the gated population was developed on a scattergram with the forward scatter (FSC) in the horizontal axis and the side scatter (SSC) in the vertical axis.
Synthetic beads having known particle sizes were measured by a flow cytometer, a regression equation of the forward scatter (FSC) intensity and the particle size was determined, and the particle sizes of cancer cells and lymphocytic cells in formalin-fixed cells were quantitatively determined based on the regression equation.
Size calibration beads purchased from Thermo Fisher Scientific (Flow Cytometry Size Calibration Kit) were used. A bead solution was prepared in accordance with the written instructions.
The bead solution was measured by a flow cytometer in the same manner as in Test 1. From the obtained data, histograms with the FSC intensity in the horizontal axis and the particle size in the vertical axis (not shown) were prepared for calibration beads of respective sizes using software FlowJo v10.6.2 manufactured by Becton Dickinson and Co, and from the histograms, the modal values of FSC intensity were calculated for beads of respective sizes. From a graph prepared by plotting the size of particles on the horizontal axis and the modal value of FSC-H intensity on the vertical axis (
From the flow cytometer measurement data for the four cell lines, which had been obtained in Test 10, histograms with the FSC intensity in the horizontal axis and the number of particles in the vertical axis (
The interval between the 5 percentile value and the 95 percentile value was considered to correspond to a principal population for each cell line. From the FSC-H intensity of each cell line in the interval, the particle size for each cell line was calculated based on the aforementioned regression equation.
The range of the calculated particle size for each cell line is shown below.
From these results, it was shown that human breast cancer cells were separated from most lymphocytes by gating particles of 10 μm or more.
Regions where lymphocytes and cancer cells can be sorted by the side scatter (SSC) intensity obtained by the flow cytometer measurement in Test 10 were determined.
From the flow cytometer measurement data for the four cell lines, which had been obtained in Test 10, histograms with the SSC intensity in the horizontal axis and the number of particles in the vertical axis (
From the distribution of the obtained SSC-H intensity of each cell line, it was shown that most human breast cancer cells were separated from lymphocytes by gating a region with a SSC-H intensity of 1.0×106.
Distribution of Breast Cancer-Derived Cell Nuclei or Lymphocyte-Derived Cell Nuclei on FSC-SSC Scattergram, and Sorting Based Thereon
Sections of a breast cancer FFPE tissue and a normal lymph node FFPE tissue were subjected to pretreatment including heating, thrombin treatment, water-flow crushing and ultrasonic crushing, then stained with a nucleic acid, and analyzed by a flow cytometer.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
As in Test 1, on histograms with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis, a region of 2n or more nuclear chromosomes was gated as cells, and the gated population was developed on a scattergram with the forward scatter (FSC) in the horizontal axis and the side scatter (SSC) in the vertical axis.
The FSC-SSC scattergrams for cancer cell-derived cell nuclei and lymphocyte-derived cell nuclei were superimposed (
It was confirmed that it was also possible to perform quantitative determination of the particle sizes of cancer cells and lymphocytic cells in Test 11 by other types of equipment.
The same procedure as in Test 11 was carried out.
The bead solution was measured by Cyflow Space from Sysmex Corporation and FACSAriaII from Becton Dickinson and Co. A FSC laser intensity gain value of 200 and a SSC laser intensity gain value of 290 were applied to the measurement by Cyflow Space from Sysmex Corporation, whereas a FSC laser intensity voltage value of 65 and a SSC laser intensity voltage value of 320 were applied to the measurement by FACSAriaII from Becton Dickinson and Co.
As in Test 11, a regression equation was calculated from a graph prepared by plotting the particle size on the horizontal axis and the modal value of FSC-H intensity on the vertical axis.
It was confirmed that it was also possible to sort cancer cells in formalin-fixed cells by other types of equipment.
The same cell lines as in Test 10 (human breast cancer cell lines T47D, MDA-MB-231 and SKBr3 and human T lymphocytic cell line Jurkat) were used.
The same procedure as in Test 10 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
As in Test 1, on histograms with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis, a region of 2n or more nuclear chromosomes was gated as cells, and the gated population was displayed on a scattergram with the forward scatter (FSC) in the horizontal axis and the side scatter (SSC) in the vertical axis (
As shown in
Particles in a region determined to be predominated by cancer cell-derived cell nuclei were fractionated, and observed with a fluorescence microscope, and microscopic test image data was analyzed to quantitatively determine the sizes thereof.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
4% BSA/TBS containing 10% normal goat serum (Wako) was added to the crushed product, and the mixture was placed still at room temperature for 30 minutes and subjected to blocking treatment. Immunofluorescent staining was performed with a pan-cytokeratin antibody (Abcam, rabbit polyclonal antibody: anti-wide spectrum cytokeratin antibody (AB9377-500)) as a primary antibody, and Goat anti-Rabbit IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 488 from Thermo Fisher Scientific as a secondary antibody. The primary antibody reaction was carried out at 37° C. for 15 minutes, and the secondary antibody reaction was carried out at room temperature for 15 minutes. DAPI Solution (Wako) was added to stain cell nuclei 10 minutes after the addition of the secondary antibody. The reactions were carried out under a light-shielding condition after addition of the secondary antibody. 0.5% BSA/TBS was used as an antibody diluting liquid, and washing with 0.5% BSA/TBS was carried out three times between the steps.
The cells were caused to pass through a 35 μm filter (380 meshes) (for flow cytometer) for Falcon (registered trademark) Cell Strainer 5 mL Tube, followed by measurement with FACSAriaII from Becton Dickinson and Co adjusted to a FSC laser intensity voltage value of 65 and a SSC laser intensity voltage value of 320. Fractionation was performed by gating a main region of 2n or more nuclear chromosomes in a histogram with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis, then developing the gated population on a scattergram with FSC in the horizontal axis and SSC in the vertical axis (
The same procedure as in Test 1 was carried out.
The major diameters and the minor diameters of cells were measured by image analysis, and average values were calculated. Image analysis was performed with image processing software ImageJ (developed by National Institutes of health). Based on luminance values of pixels derived from luminescence of DAPI, the luminance value was binarized to determine cell nuclei, information from the scale bar was used as a reference to calculate the major diameters and the minor diameters of cell nuclei, and average values of the major diameters and the minor diameters of cell nuclei in one visual field were determined (Table 8)
Measurement with Fraction of Lymphocytic Cell Nuclei by Other Types of Equipment
A population of particles in Area 2, which was determined to be abundant in lymphocyte-derived cell nuclei and fractionated in Test 16, was measured by other types of flow cytometers, and how many lymphocyte-derived cell nuclei were mixed up in a region determined to allow cancer cell-derived cell nuclei to be sorted in Tests 13 and 15 was examined.
The fraction of Area 2 fractionated in Test 2 was used.
The same procedure as in tests 1 and 14 was carried out.
The acquired flow cytometer data was not subjected to gating processing, and the population was developed on a FSC-SSC scattergram.
As shown in
Sorting of Cancer Cells and Lymphocytic Cells when Formalin-Fixed Cells are Treated with Different Enzymes
Breast cancer cells and lymphocytic cells fixed with formalin were subjected to pretreatment including treatments with different enzymes, nucleic acid was stained, the treated product was then analyzed by a flow cytometer, and distributions on FSC-SSC scattergrams were compared.
Human breast cancer cell lines T47D, MDA-MB-231 and SKBr3 and the human T lymphocytic cell line Jurkat were acquired from ATCC, and used in the present test.
The same procedure as in Test 10 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
As in Test 1, populations were gated, and the gated populations were developed on scattergrams with the forward scatter (FSC) in the horizontal axis and the side scatter (SSC) in the vertical axis. For comparing effects of different enzymes used for the treatment, the scattergram for the lymphocytic cells was superimposed on the scattergram for each of the breast cancer cell lines.
As shown in
Distribution of Breast Cancer Tissue-Derived Cell Nuclei or Lymphocyte-Derived Cell Nuclei and Sorting Based Thereon when FFPE Tissue Section are Treated with Different Enzymes
Breast cancer and normal lymph node FFPE tissues were subjected to pretreatment including treatments with different enzymes, nucleic acid was stained, the treated product was then analyzed by a flow cytometer, and distributions on FSC-SSC scattergrams were compared.
Breast cancer and normal lymph node FFPE tissues purchased from ProteoGenex, Inc were used as measurement samples.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
As in Test 1, populations were gated, and the gated populations were developed on scattergrams with the forward scatter (FSC) in the horizontal axis and the side scatter (SSC) in the vertical axis. For comparing effects of different enzymes used for the treatment, the scattergram for the normal lymph node FFPE tissue was superimposed on the scattergram for the breast cancer FFPE tissue.
As shown in
Comparative Examination of Ki-67-Positive Ratios with and without Gating of Cancer Cell-Derived Cell Nucleus Region and Positive Ratio by IHC Method by Pathologist, and Agreement Ratio
A FFPE tissue section was subjected to pretreatment, immuno-fluorescently stained with a Ki-67 antibody, and then measured by a flow cytometer. Data analysis was performed to examine a correlation between positive ratios obtained with and without gating of the cancer cell-derived cell nucleus region and a positive ratio by the IHC method by a pathologist. In addition, positive and negative agreement ratios were examined by statistical analysis.
49 FFPE tissue blocks obtained from 49 patients with different Ki-67-positive ratios from the IHC method and purchased from ProteoGenex, Inc were used.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
4% BSA/TBS containing 10% normal goat serum (Wako) was added, and the mixture was placed still at room temperature for 30 minutes and subjected to blocking treatment. Immunofluorescent staining was performed with a Ki-67 antibody (Agilent, clone: MIB-1, mouse monoclonal antibody) as a primary antibody, and Goat anti-Mouse IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 647 from Thermo Fisher Scientific as a secondary antibody. The primary antibody reaction was carried out at 37° C. for 15 minutes, and the secondary antibody reaction was carried out at room temperature for 15 minutes. DAPI Solution (Wako) was added to stain cell nuclei 10 minutes after the addition of the secondary antibody. The reactions were carried out under a light-shielding condition after addition of the secondary antibody. 0.5% BSA/TBS was used as an antibody diluting liquid, and washing with 0.5% BSA/TBS was carried out three times between the steps. Instead of the primary antibody, a corresponding antibody identical in type and concentration to the primary antibody was used as an isotype matched control.
The same procedure as in Test 1 was carried out.
Analysis was performed using FlowJo v10.6.2. A main region of 2n or more nuclear chromosomes was gated in a histogram with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis. Subsequently, for the gated population, a scattergram with FSC-H (forward scatter) in the horizontal axis and SSC-H (side scatter) in the vertical axis was developed, and a region with a FSC-H intensity of 2.00×106 to 5.00×106 and a SSC-H intensity of 1.00×106 to 2.00×106 was gated as a cancer cell nucleus region. For the population gated as a cancer cell nucleus region and the population without gating, histograms with the fluorescence intensity (corresponding to the amount of Ki-67) in the horizontal axis and the number of particles in the vertical axis were prepared. On each of the histograms, a histogram of an isotype matched control was superimposed. The threshold value of Ki-67-positive nuclei was set to the 95 percentile value of the isotype matched control. The Ki-67-positive ratio was calculated as a ratio of the number of Ki-67-positive nuclei with respect to the number of all cell nuclei. A value obtained by subtracting 5% from the obtained positive ratio was used because the cut-off of positive nuclei was set to the 95 percentile value of the isotype matched control.
The Ki-67-positive ratio by the IHC method was calculated by a hotspot method with a Ki-67 antibody (Agilent, clone: MIB-1, mouse monoclonal antibody) as a primary antibody.
Statistical analysis was performed using MedCalc v19.4.1 from MedCalc Software. The results by the IHC method were binarized with the cut-offs of Ki-67-positive and negative cell nuclei set to 20%, and ROC analysis was performed on the obtained values together with results with or without gating in the flow cytometer to calculate AUC.
From the above, it was confirmed that by gating, cancer cell nuclei were concentrated to improve the correlation with the IHC method and the positive/negative agreement, so that it was possible to accurately detect Ki-67 in cancer cell nuclei.
Examination of ER- and PgR-Positive Ratios with and without Gating of Cancer Cell-Derived Cell Nucleus Region
A FFPE tissue section was subjected to pretreatment, immuno-fluorescently stained with an ER antibody and a PgR antibody, and then measured by a flow cytometer. Data analysis was performed to compare positive ratios with and without gating of the cancer cell-derived cell nucleus region.
ER-positive specimen A (Allred Score ER8) and PgR-positive specimen B (Allred Score PgR8) purchased from ProteoGenex, Inc were used as ER- and PgR-positive samples, and FFPE tissue sections of ER- and PgR-negative specimens C (Allred Score ER0 and PgR0) were used as ER- and PgR-negative samples.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
4% BSA/TBS containing 10% normal goat serum (Wako) was added, and the mixture was placed still at room temperature for 30 minutes and subjected to blocking treatment. Immunofluorescent staining was performed with an ER antibody (Agilent, clone: EP1, rabbit monoclonal antibody) or a PgR antibody (Agilent, clone: PgR636, mouse monoclonal antibody) as a primary antibody and Goat anti-Rabbit IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 488 and Goat anti-Mouse IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 647 from Thermo Fisher Scientific as secondary antibodies. The primary antibody reaction was carried out at 37° C. for 15 minutes, and the secondary antibody reaction was carried out at room temperature for 15 minutes. DAPI Solution (Wako) was added to stain cell nuclei 10 minutes after the addition of the secondary antibody. The reactions were carried out under a light-shielding condition after addition of the secondary antibody. 0.5% BSA/TBS was used as an antibody diluting liquid, and washing with 0.5% BSA/TBS was carried out three times between the steps. Instead of the primary antibody, a corresponding antibody identical in type and concentration to the primary antibody was used as an isotype matched control. A rabbit IgG antibody from Cell Signaling Technology was used as the ER antibody, and a mouse IgG antibody from Agilent Technology was used as the PgR antibody.
The same procedure as in Test 1 was carried out.
Analysis was performed using FlowJo v10.6.2. A main region of 2n or more nuclear chromosomes was gated in a histogram with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis. For the gated population, a scattergram with FSC-H (forward scatter) in the horizontal axis and SSC-H (side scatter) in the vertical axis was developed, and a region with a FSC-H intensity of 2.00×106 to 5.00×106 and a SSC-H intensity of 1.00×106 to 2.00×106 was gated as a cancer cell nucleus region. For the population gated as a cancer cell nucleus region or the population without gating, histograms with the fluorescence intensity (corresponding to the amount of ER or PgR) in the horizontal axis and the number of particles in the vertical axis were prepared. On each of the histograms, a histogram of an isotype matched control was superimposed (
As shown in
Examination of Cytokeratin Subtype-Positive Ratios with and without Gating of Cancer Cell-Derived Cell Nucleus Regions
A FFPE tissue section was subjected to pretreatment, immuno-fluorescently stained with cytokeratin 7 and 20 antibodies, and then measured by a flow cytometer. Data analysis was performed to compare positive ratios with and without gating of the cancer cell-derived cell nucleus region.
A breast cancer FFPE tissue block purchased from ProteoGenex, Inc was used.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
4% BSA/TBS containing 10% normal goat serum (Wako) was added, and the mixture was placed still at room temperature for 30 minutes and subjected to blocking treatment. Immunofluorescent staining was performed by double staining with a cytokeratin 7 antibody (Abcam, rabbit monoclonal antibody) and a cytokeratin 20 antibody (Abcam, mouse monoclonal antibody) as primary antibodies and Goat anti-Rabbit IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 488 and Goat anti-Mouse IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 647 from Thermo Fisher Scientific as secondary antibodies. The primary antibody reaction was carried out at 37° C. for 15 minutes, and the secondary antibody reaction was carried out at room temperature for 15 minutes. DAPI Solution (Wako) was added to stain cell nuclei 10 minutes after the addition of the secondary antibody. The reactions were carried out under alight-shielding condition after addition of the secondary antibody. 0.5% BSA/TBS was used as an antibody diluting liquid, and washing with 0.5% BSA/TBS was carried out three times between the steps. Instead of the primary antibodies, corresponding antibodies identical in type to the primary antibodies were used as isotype matched controls. A rabbit IgG antibody from Cell Signaling Technology was used as the cytokeratin 7 antibody, and a mouse IgG antibody from Agilent Technology was used as the cytokeratin 20 antibody.
The same procedure as in Test 1 was carried out.
Analysis was performed using FlowJo v 10.6.2. A main region of 2n or more nuclear chromosomes was gated in a diagram with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis. For the gated population, a scattergram with FSC-H (forward scatter) in the horizontal axis and SSC-H (side scatter) in the vertical axis was developed, and a region with a FSC-H intensity of 2.00×106 to 5.00×106 and a SSC-H intensity of 1.00−106 to 2.00×106 was gated as a cancer specific region. For the population gated as a cancer cell nucleus region or the population without gating, histograms with the fluorescence intensity (corresponding to the amount of cytokeratin 7 or 20) in the horizontal axis and the number of particles in the vertical axis were prepared. On each of the histograms, a histogram of an isotype matched control was superimposed (
As shown in
FFPE tissue sections of a cancer part, a non-cancerous part (normal cells) and a normal lymph node derived from one patient with breast cancer were subjected to a predetermined pretreatment, nucleic acid was stained, the treated product was then analyzed by a flow cytometer, and proportions of lymphocyte-derived cell nuclei and normal cell-derived cell nuclei in a specific region on a FSC-SSC scattergram were examined.
FFPE tissue blocks of a cancer part, a non-cancerous part and a normal lymph node derived from one patient with breast cancer and purchased from ProteoGenex, Inc were used.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
Analysis was performed using FlowJo v10.6.2. A main region of 2n or more nuclear chromosomes was gated in a diagram with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis. Subsequently, the gated population was developed on a scattergram with FSC-H (forward scatter) in the horizontal axis and SSC-H (side scatter) in the vertical axis.
The proportions of the cell nuclei of respective types in areas 3 and 4 are shown below.
The proportions of normal cell nuclei and cancer cell nuclei present in Area 3 are 4.7% and 3.3%, respectively. In Area 3, lymphocyte-derived cell nuclei were concentrated. The proportions of lymphocyte-derived cell nuclei and cancer cell nuclei present in Area 4 are 0.6% and 1.9%, respectively. In Area 4, normal cell nuclei were concentrated. Thus, it was shown that it was possible to separate and concentrate lymphocyte-derived cell nuclei and normal cell nuclei by gating areas 3 and 4.
Examination of Ki-67-Positive Ratios with and without Gating of Cancer-Derived Cell Nucleus Region in Bowel Cancer Case
Bowel cancer FFPE tissue sections were subjected to predetermined pretreatment, immuno-fluorescently stained with a Ki-67 antibody, and then measured by a flow cytometer. Data analysis was performed to compare positive ratios with and without gating of the cancer cell-derived cell nucleus region.
Bowel FFPE tissue blocks (case 1: sigmoid, case 2: rectum) purchased from Proteogenex, Inc were used.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
The tissues after physical crushing were immuno-fluorescently stained in the same manner as in Test 20.
The same procedure as in Test 1 was carried out.
Analysis was performed using FlowJo v 10.6.2. A main region of 2n or more nuclear chromosomes was gated in a diagram with the fluorescence intensity of DAPI-A in the horizontal axis and the number of particles in the vertical axis. Subsequently, a scattergram with FSC-H (forward scatter) in the horizontal axis and SSC-H (side scatter) in the vertical axis was developed, and a region with a FSC-H intensity of 2.00×106 to 5.00×106 and a SSC-H intensity of 1.00×106 to 2.00×106 was gated as a cancer cell nucleus region. The Ki-67-positive ratio was calculated as a ratio of the number of Ki-67-positive nuclei with respect to the number of all cell nuclei. The threshold value of positive nuclei was set to the 95 percentile value of the isotype matched control. The positive ratio without gating of the cancer cell nucleus region was similarly calculated.
As shown in
Examination of Cytokeratin Subtype-Positive Ratios with and without Gating of Cancer-Derived Cell Nucleus Region in Bowel Cancer Case
Bowel cancer FFPE tissue sections were subjected to predetermined pretreatment, immuno-fluorescently stained with cytokeratin 7 and 20 antibodies, and then measured by a flow cytometer. Data analysis was performed to compare positive ratios from with and without gating of the cancer cell-derived cell nucleus region.
Bowel cancer FFPE tissue blocks purchased from Proteogenex, Inc were used.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
The tissues after physical crushing were immuno-fluorescently stained in the same manner as in Test 22.
The same procedure as in Test 1 was carried out.
The same procedure as in Test 22 was carried out.
As shown in
FFPE tissue sections of a cancer part and a non-cancerous part (normal cells) derived from a patient with bowel cancer having KRAS gene mutation were subjected to predetermined pretreatment, and then mixed to prepare a sample having a low cancer proportion. Subsequently, the cancer cell nuclei were concentrated by a cell sorter, and real time PCR was used to detect KRAS gene mutation.
FFPE tissue blocks of a cancer part and a non-cancerous part derived from one patient with bowel cancer having KRASG12D mutation purchased from ProteoGenex, Inc were used.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
The suspension liquid obtained by crushing was filtered through a 35 μm filter (380 meshes) (for flow cytometer) for Falcon (registered trademark) Cell Strainer 5 mL Tube, followed by measurement with a laser intensity gain value (FSC: 400, SSC: 400) using a flow cytometer (Agilent: NovoCyte Quanteon Flow Cytometer), whereby the concentration of particles (number of particles/mL) was determined.
Cancer part- and non-cancerous part-derived suspension liquids of which particle concentrations had been measured were mixed as necessary to prepare suspension liquids in which the proportion of cells from the cancer part was 10% or 100% and the total number of particles was 100,000.
The samples having different proportions of particles from the cancer part were measured using FACSAriaII from Becton Dickinson and Co (FSC laser intensity voltage value: 65, SSC laser intensity voltage value: 320). A scattergram with FSC in the horizontal axis and SSC in the vertical axis was prepared, about 30,000 cells were fractionated from a region identical to Area 1 of
Using QIAamp DNA FFPE Tissue Kit from QUIAGEN N.V., DNA was extracted from samples of cells fractionated by the cell sorter and samples of non-fractionated cells, and the DAN was purified. The concentration of the purified DNA was calculated from an absorbance at 260 nm using a micro spectrophotometer DS-11+ manufactured by Scrum Inc.
PCR was performed on the purified DNA using the following reagents and Step One Plus (registered trademark) Real Time PCR System from ThermoFisher Scientific.
A cycle of reaction, in which the reaction solution is exposed to a first temperature of 95° C. for 20 seconds (degeneration reaction), a second temperature of 58° C. for 30 seconds (annealing reaction) and a third temperature of 72° C. for 45 seconds (extension reaction) once, was carried out 50 times, and fluorescence was detected.
When the cancer proportion was as low as 10%, fractionation of the cancer cell nucleus region made amplification faster by about 3 cycles. On the other hand, when the cancer proportion was 100%, there was no change in amplification rate. Thus, it is indicated that DNA derived from cancer cells was also concentrated by fractionating the cancer cell nucleus region.
Examination of DNA Aneuploidy Peak Detections with and without Gating of Cancer Cell-Derived Cell Nucleus Regions
A FFPE tissue section was subjected to pretreatment, nucleic acid was stained, and the treated product was then tested by a flow cytometer. Data analysis was performed to compare DNA aneuploidy peak detections with and without gating of the cancer cell-derived cell nucleus region.
Breast cancer FFPE tissue blocks (n=3) purchased from ProteoGenex, Inc were used.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in test 8 was carried out.
The same procedure as in test 7 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 1 was carried out.
Analysis was performed using FlowJo v 10.6.2. Data analysis was performed by the following procedure (
As shown in
<Test 28> Comparison Examination of DNA Index Calculated from DNA Aneuploidy Peak and DNA Index Calculated from DNA Aneuploidy Peak Detected by Cytokeratin and Vimentin Staining after Gating of Cancer Cell-Derived Cell Nucleus Region
A correlation between a DNA index calculated with DNA aneuploidy peaks obtained in the same manner as in Test 27 except that the number of specimens was 17 and a DNA index calculated from a DNA aneuploidy peak detected by cytokeratin and vimentin staining after gating of a cancer cell-derived cell nucleus region was examined.
A breast cancer FFPE tissue block purchased from ProteoGenex, Inc was used.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedure as in Test 2 was carried out.
The same procedures as in tests 8, 7 and 2 were carried out, respectively.
A collagenase reagent (RPMI 1640, 3,000 PU/mL dispase, 2,500 U/mL collagenase type III, 10 mg/mL RNase I) was added to the sample after the heating treatment, and the mixture was heated on a heat block at 37° C. for 20 minutes. Subsequently, 4% BSA/TBS containing 10% normal goat serum (Wako) was added, and the mixture was placed still at room temperature for 30 minutes and subjected to blocking treatment. Immunofluorescent staining was performed by double staining with a cytokeratin antibody (Abcam, rabbit monoclonal antibody) and a vimentin antibody (Abcam, mouse monoclonal antibody) as primary antibodies and Goat anti-Rabbit IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 488 and Goat anti-Mouse IgG (H+L) Cross-Adsorbed Secondary Antibody Alexa Fluor 647 from Thermo Fisher Scientific as secondary antibodies. The primary antibody reaction was carried out at 37° C. for 15 minutes, and the secondary antibody reaction was carried out at room temperature for 15 minutes. DAPI Solution (Wako) was added to stain cell nuclei 10 minutes after the addition of the secondary antibody. The reactions were carried out under a light-shielding condition after addition of the secondary antibody. 0.5% BSA/TBS was used as an antibody diluting liquid, and washing with 0.5% BSA/TBS was carried out three times between the steps. Instead of the primary antibodies, corresponding antibodies identical in type to the primary antibodies were used as isotype matched controls. A rabbit IgG antibody from Cell Signaling Technology was used as the cytokeratin antibody, and a mouse IgG antibody from Agilent Technology was used as the vimentin antibody.
The same procedure as in Test 1 was carried out.
As illustrated in
In the conventional method, gating of a main region of 2n or more nuclear chromosomes and removal of doublets were similarly performed. Subsequently, a scattergram with the fluorescence intensity of cytokeratin in the horizontal axis and the fluorescence intensity of vimentin in the vertical axis was developed. Cytokeratin-positive and vimentin-negative regions were gated as cancer cell regions, and cytokeratin-negative and vimentin-positive regions were gated as interstitial cell regions. For each of the gated populations, a modal value of the fluorescence intensity of DAPI-A was acquired, and the ratio of the modal value for the cancer cell region to the modal value for the interstitial cell region (modal value for cancer cell region/modal value for interstitial region) was calculated, and defined as a DNA index.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-159878 | Sep 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/022101 | 5/31/2022 | WO |
