US 20050042595 A1
Stem cells, including those designated as multipotent amniotic fluid stem cells (MAFSC) cells are found in the amniotic fluid of mammals, including humans. MAFSCs are fetal, multipotent stem cells that can be used for any desired stem cell utility, including treatment of individuals in need of tissue replacement or gene therapy. Methods of banking MAFSCs derived from the amniotic fluid cells of pregnant individuals are disclosed. Amniotic fluid-derived cells are banked for the purpose of access to transplantation antigen-compatible or syngeneic multipotent stem cells.
1. A cell bank system, comprising:
a plurality of preserved, viable samples, containing amniotic fluid-derived cells, wherein said samples are from a plurality of individuals; and
a database containing one or more data fields that allow for specific identification and retrieval of individual samples.
2. The cell bank system of
3. The cell bank system of
4. The cell bank system of
5. The cell bank system of
6. The cell bank system of
7. The cell bank system of
8. A method for banking stem cells, comprising:
obtaining a plurality of viable samples containing amniotic-fluid-derived stem cells, wherein said samples are from the amniotic fluid of a plurality of individual fetuses;
preserving and storing the samples in a manner that preserves viability of at least some of said stem cells;
storing data relating to the identity of individual samples; and
providing for retrieval of said individual samples by or on behalf of the individual from whom the sample was obtained.
9. The method of
10. The method of
11. The method of
12. The method of
13. The method of
14. A collection comprising a plurality of viable stem cells derived from amniotic fluid of different fetuses.
15. The collection of
16. The collection of
17. The collection of
18. A method of preparing amniotic fluid derived stem cells (MAFSC) for a potential future use, comprising:
obtaining amniotic fluid containing live cells;
culturing MAFSC cells isolated from said amniotic fluid; and
cryopreserving said MAFSC cells.
19. A storage bank of multiple samples of amniotic fluid-derived cells or MAFSCs taken from multiple individuals, wherein the samples are preserved in such a way as to be viable upon recovery.
20. The storage bank of
21. The storage bank of
22. The storage bank of
23. The storage bank of
24. The cell bank system of
25. The cell bank system of
26. The cell bank system of
27. The cell bank system of
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This application claims priority under 35 U.S.C. §119 to U.S. Provisional Application No. 60/495,513, filed Aug. 14, 2003, and U.S. Provisional Application No. 60/495,437, filed Aug. 14, 2003, the disclosures of which are incorporated by reference herein in their entireties.
1. Field of the Invention
This invention relates to the field of stem cell research. Specifically, the invention relates to the preservation and banking of amniotic fluid-derived cells, or multipotent amniotic fluid-derived stem cells of individuals. The cryopreserved amniotic fluid-derived cells can be stored indefinitely. Thawed cells can be used to grow stem cell lines which can create differentiated cells, such as specific cell types or tissue types. These differentiated cells are capable of being transplanted into the individual or into unrelated matching individuals if needed.
2. Description of the Related Art
Stem cells can give rise to many types of differentiated cells, and thus may be useful to treat many types of diseases. Stem cells have the ability to divide for indefinite periods in culture and to give rise to specialized cells. There are several types of stem cells, such as embryonic stem cells, which are undifferentiated cells from the embryo, and adult stem cells, which are undifferentiated cells derived from various mature tissues.
Embryonic stem cells have the potential to become a wide variety of specialized cell types. This ability of an embryonic stem cell to become a variety of cell types is termed “pluripotent.” Embryonic stem cells can be differentiated into a host of cell types and tissue types which can be used for basic research, drug discovery, treatment and prevention of diseases. For example, U.S. Pat. No. 6,506,574 to Rambhatla, which is incorporated by reference herein in its entirety, discloses methods of differentiating embryonic stem cell cultures into hepatocyte lineage cells. Other methods for the preparation of embryonic stem cells are disclosed, for example, in U.S. Pat. No. 6,200,806 to Thomson; U.S. Pat. No. 5,670,372 to Hogan, and U.S. Pat. No. 6,432,711 to Dinsmore, each of which is incorporated by reference herein in its entirety.
Human Embryonic Stem cells (hES) are derived from the inner cell mass of the blastocyst, the earliest stage of embryonic development of the fertilized egg. The blastocyst is a preimplantation stage of the embryo, a stage before the embryo would implant in the uterine wall. When cultured on an inactivated feeder layer of cells according to conditions described by Thompson and colleagues (Thomson, et al., (1995) Proc. Natl. Acad. Sci. U.S.A. 92:7844-7848; Thomson, et al. (1998) Science 282:1145-1147; Marshall, et al., (2001) Methods Mol. Biol. 158:11-18, each of which is incorporated by reference herein in its entirety the inner layer cells of the blastocyst can be grown in vitro indefinitely in an undifferentiated state. Properly propagated hES cells have unlimited potential to double while maintaining their capacity of differentiating into the three layers of the embryo, Ectoderm (Ec), Mesoderm (me) and Endoderm (En); they are pluripotent. When grown as pluripotent hES, the cells maintain a euploid karyotype and are not prone to senescence. hES cells have been differentiated in vitro into skin and brain (Ec), heart, muscle, kidney and blood (Me), and into pancreatic, thyroid and lung cells (En) (Fraichard, et al., (1995) J Cell Sci. 108:3181-3188; Itskovitz-Eldor, et al., (2000). Mol. Med. 6:88-95; Lee, et al., (2000) Nat. Biotechnol. 18:675-679; Liu, et al., (2000) Proc. Natl. Acad. Sci. U.S.A. 97:6126-6131; Lumelsky, et al., (2001) Science 292:1389-1394; Maltsev, et al., (1993). Mech. Dev. 44:41-50; Odorico, et al., (2001) Stem Cells 19:193-204. Potocnik, et al., EMBO. J. 13:5274-5283; Reubinoff, et al., (2000) Nat. Biotechnol. 18:399-404; Schuldiner, et al., (2001) Proc. Natl. Acad. Sci. USA 97:1997:11307-11312; Kim, et al., (2002) Nature 418:50-56; Wichterle, et al., (2002) Cell 110:385-397), each of which is incorporated by reference herein in its entirety.
Human embyronic stem cells display a distinct group of cell surface antigens, SSEA-3, SSEA-4, TRA-2-54 (alkaline phosphatase), TRA-1-60 and TRA-1-81, in addition to expressing specific transcription factors OCT-4, NANOG, SOX-2, FGF-4 and REX-1 (Henderson, et al., (2002) Stem Cells 20:329-337; Draper, et al., (2002). J. Anat. 200:249-258; Mitsui et al., (2003) Cell 113:631-642; Chambers et al., (2003) Cell 113:643-655), each of which is incorporated by reference herein in its entirety.
Additionally, hES cells (i) are capable of symmetrical division in vitro without differentiating; (ii) can integrate into all fetal tissues during in vivo development; (iii) are capable of colonizing the germ line and give rise to egg or sperm cells; (iv) develop into teratocarcinomas in immunologically impaired adult mice—another measure of pluripotency, and lack the G1 checkpoint in the cell cycle like somatic cells but spend most of their time in S phase.
Stem cells can also be derived from nonembryonic sources. For example, an additional class of human stem cells are the mesenchymal or adult stem cells (MSC). Adult stem cells are undifferentiated, like embryonic stem cells, but are present in differentiated tissues. Adult stem cells are capable of differentiation into the cell types from the tissue that the adult stem cell originated. Adult stem cells (MSC) have been derived from the nervous system (McKay, R. (1997) Science 276:66-71. Shihabuddin, et al., (1999) Mol. Med. Today 5:474-480), bone marrow (Pittenger, et al., (1999) Science 284:143-147; Pittenger, M. F. and Marshak, D. R. (2001). In: Mesenchymal stem cells of human adult bone marrow. Marshak, D. R., Gardner, D. K., and Gottlieb, D. eds. (Cold Spring Harbor, N.Y.: Cold Spring Harbor Laboratory Press) 349-374); adipose tissue (Gronthos, et al., (2001) J. Cell. Physiol. 189:54-63), dermis (Toma, et al., (2001) Nature cell Biol. 3:778-784) and pancreas and liver (Deutsch, et al., (2001) Development 128:871-881), each of which is incorporated by reference herein in its entirety.
The political, moral and ethical issues around hES cells, as well as the perceived difficulties of expanding undifferentiated adult stem cells in culture, while maintaining a genetically normal genome, are major barriers in the development of human cell replacement therapy. Further, what is needed in the art is a method of isolating, storing, banking, and retrieving novel sources of multipotent or pluripotent human stem cells so that they can be revived and utilized at a later date.
Embodiments of the invention include a cell bank system having preserved, viable samples from many individuals, where the samples contain amniotic fluid-derived cells, and a database allowing for specific identification and retrieval of individual samples. The database may include information allowing association of an individual sample with the sample donor, and the sample may be retrieved by the donor. The samples may contain amniotic fluid, and may contain multipotent or pluripotent stem cells. The amniotic fluid-derived cells comprise pluripotent stem cells, or can be multipotent stem cells. For example, the amniotic fluid-derived cells can be multipotent stem cells characterized by a) the ability to grow in continuous culture for at least 60 generations, and b) the presence of at least one, or two, or three, or four, or five, or all of the markers selected from the group consisting of: SSEA3, SSEA4, Tra1-60, Tra1-81, Tra2-54, and Oct-4. The stem cells can further express at least one marker selected from the group consisting of: HLA Class I, CD13, CD44, CD49b, and CD105. The amniotic fluid-derived cells can be pluripotent stem cells characterized by a) the ability to grow in continuous culture for at least 60 generations, and b) the presence of at least one, or two, or three, or four, or five, or all of the markers selected from the group consisting of: SSEA3, SSEA4, Tra1-60, Tra1-81, Tra2-54, and Oct-4. The stem cells can further express at least one marker selected from the group consisting of: HLA Class I, CD13, CD44, CD49b, and CD105.
Additional embodiments of the invention include methods for banking stem cells by obtaining viable samples containing amniotic-fluid-derived stem cells, which were derived from the amniotic fluid of individual fetuses, then preserving and storing the samples in a way that allows viability of at least some of the stem cells, storing data relating to the identity of the individual samples; and allowing the retrieval of individual samples by the individual from whom the sample was obtained. The samples may be cryopreserved, and may contain MAFCS, amniotic fluid, multopotent and/or pluripotent stem cells.
Further embodiments of the invention include methods for banking stem cells by obtaining viable samples containing amniotic-fluid-derived stem cells derived from the amniotic fluid of individual fetuses, preserving and storing the samples in a way that preserves viability of at least some of the stem cells, storing data relating to tissue compatibility characteristics of individual samples; and providing for retrieval of an individual sample by an individual sharing tissue compatibility characteristics of the sample. Such samples may be cryopreserved, and may contain MAFCS, amniotic fluid, multopotent and/or pluripotent stem cells.
Yet further embodiments of the invention include collections having numerous viable stem cell samples derived from amniotic fluid of different fetuses. Such samples may be cryopreserved, and may contain MAFCS, amniotic fluid, multopotent and/or pluripotent stem cells.
Additional embodiments of the invention include methods of preparing amniotic fluid-derived cells for a potential future use, by obtaining and cryopreserving amniotic fluid containing live amniotic stem cells. The cryopreserving step may be performed in a medium which contains DMSO, preferably at 1% to 80%, and more preferably 10% to 40% (V/V) DMSO. Amniotic fluid may also be present, preferably at about 15% to 35% (V/V).
Further embodiments of the invention include methods for preparing amniotic fluid derived stem cells or multipotent amniotic fluid derived stem cells (MAFSC) for a potential future use by obtaining amniotic fluid containing live cells, then culturing MAFSC cells isolated from said amniotic fluid, then cryopreserving the MAFSC cells. The cryopreserving step may be performed in a medium which contains DMSO, preferably at 1% to 80%, and more preferably 10% to 40% (V/V) DMSO. Amniotic fluid may also be present, preferably at about 15% to 35% (V/V).
Additional embodiments include storage banks of multiple samples of amniotic fluid-derived cells or MAFSCs taken from multiple individuals, where the samples are preserved in such a way as to be viable upon recovery. The cells may be cryopreserved in a medium having DMSO. At least some of the samples can be differentiable human stem cells, which may be multipotent or pluripotent.
Additional embodiments include data storage media containing a database having a first data item associated with each of many preserved amniotic-fluid-derived stem cell samples, containing location information for the samples; and a second data item associated with each sample containing identifying information for the sample. The second data item can include, for example, the identity of a fetus from whom the sample was obtained, tissue compatibility information, and/or histocompatibility information for the stem cells.
A newly discovered source of human stem cells is described herein and in co-pending application Ser. No. 60/495,437, which is incorporated by reference herein in its entirety.
The cells, coined Multipotent Amniotic Fetal Stem Cells (MAFSC), are immortal in culture, maintain euploidy for >1 year in culture, share markers with human ES cells, and are capable of differentiating into all three germ layers of the developing embryo, Endoderm, Mesoderm and Ectoderm. These human stem cells are found in the amnion harvested during the first trimester of human pregnancies.
Both fresh amniotic fluid derived cells, and the cultured MAFSC cells derived from them, may be stored indefinitely. When a need arises, an aliquot of the cells can be thawed, cultured, and used as needed. The long term storage of amniotic fluid derived cells allows an individual to have a supply of stem cells taken while the individual is still in the womb, to be stored in such a way as to provide a supply of cells for emergency or other uses throughout the individual's lifetime. The long term storage or “banking” of amniotic fluid-derived cells or cultured MAFSCs is disclosed herein.
While amniotic fluid contains multiple morphologically-distinguishable cell types, the majority of the cells are prone to senescence and are lost from cultures grown under MAFSC culture conditions. More than 80% of amniotic fluid harvests from normal 16-18 week pregnancies give rise to continuous MAFSC lines. The MAFSCs may be harvested from anmniotic fluid from pregnant females at any stage in the gestation period.
MAFSC are of fetal origin, and have a normal diploid karyotype. Additionally, MAFSC cells are devoid of tumorgenic properties: unlike hEC cells, human MAFSC cells do not grow into teratocarcinomas when injected into SCID mice. This property may be especially useful in using MAFSC cells or their derivatives for human gene therapy purposes.
The term “stem cell” refers to any cells that have the ability to divide for indefinite periods of time and to give rise to specialized cells. The term “long term stem cells” refers more specifically to those stem cells that are capable of self-renewal over indefinite periods of time.
The MAFSC cells of the invention have been shown to be multipotent, as several main cell types have been derived from them. As used herein, the term “multipotent” refers to the ability of MAFSC to differentiate into several main cell types. The MAFSC cells may also be propagated under specific conditions to become “pluripotent.” The term “pluripotent stem cells” describes stem cells that are capable of differentiating into any type of body cell, when cultured under conditions that give rise to the particular cell type.
The MAFSCs may be isolated as described, for example, in Example 1. Briefly, the sample of amniotic fluid (AF) can be was removed from a pregnant female at any time during thee gestation period. Cells to be cultured are then removed from the amniotic fluid, preferably by centrifugation or filtration. The cells can then be plated on medium as disclosed in Example 1, or other suitable growth medium.
Typically, the cells are grown in a nutrient medium such as the medium shown in Example 1. Expansion of the undifferentiated amniotic fluid-derived cells can be achieved by culturing the cells in defined media containing low amounts of serum or no serum at all, using, for example, recombinant growth promoting factors. The term “undifferentiated” refers to cells that have not become specialized cell types. A “nutrient medium” is a medium for culturing cells containing nutrients that promote proliferation. The nutrient medium may contain any of the following in an appropriate combination: isotonic saline, buffer, amino acids, antibiotics, serum or serum replacement, and exogenously added factors.
The MAFSCs are preferably isolated from humans. However, the MAFSCs may be isolated in a similar manner from other species. Examples of species that may be used to derive the MAFSCs include but are not limited to mammals, humans, primates, dogs, cats, goats, elephants, endangered species, cattle, horses, pigs, mice, rabbits, and the like.
The amniotic fluid-derived cells and MAFSC can be recognized by their specific cell surface proteins or by the presence of specific cellular proteins. Typically, specific cell types have specific cell surface proteins. These surface proteins can be used as “markers” to determine or confirm specific cell types. Typically, these surface markers can be visualized using antibody-based technology or other detection methods. The surface markers of the isolated MAFSC cells derived from independently-harvested amniotic fluid samples were tested for a range of cell surface and other markers, using monoclonal antibodies and FACS analysis (see Examples 2 and 3, and Table 1). These cells are characterized by the following cell surface markers: SSEA3, SSEA4, Tra1-60, Tra1-81, Tra2-54 but are distinguished from mouse ES cells in that these cells do not express the cell surface marker SSEA1. Additionally, MAFSC express the stem cell transcription factor Oct-4.
The anmiotic fluid-derived cells can be stored or “banked” in a manner that allows the cells to be revived as needed in the future. An aliquot of the undifferentiated cells can be removed at any time, to be grown into cultures of many undifferentiated cells and then differentiated into a particular cell type or tissue type, and may then be used to treat a disease or to replace malfunctioning tissues in a patient. Since the cells are harvested from the amniotic fluid, the cells can be stored so that an individual can have access to his or her own undifferentiated cells for an entire lifetime. Alternatively, the cells can be used by individuals other than the original donor.
In addition, although the principal exemplary disclosure of the present application relates to amniotic stem cells, the cell banking and retrieval disclosure herein is similarly applicable to any stem cell types, including those derived from embryos, placenta, umbilicus, infants, children, and adults.
In one embodiment of the present invention, a stem cell bank is provided for storing amniotic fluid-derived cell samples. In additional embodiments of the present invention, methods for administering such a stem cell bank are provided. U.S. Published Patent Application No. 20030215942, which is incorporated by reference herein in its entirety, provides an example of a stem cell bank system.
Using methods such as those described above and in Examples 5 and 6, below, the isolation and in vitro propagation of stem cell samples from amniocentesis harvests and their cryopreservation facilitates the establishment of a “bank” of transplantable human stem cells. The method described herein allows viable stem cells of any individual to be obtained from the amniotic fluid (for example, from an amniocentesis procedure) and be available for use at any time in the future. Any number of individuals may have cells stored in this manner. Because it is possible to store smaller aliquots of AF or MASFCs, the banking procedure could take up a relatively small space. Therefore, the cells of many individuals could be stored or “banked” on a short term or long term basis, with relatively little expense.
In some embodiments of the present invention, a portion of the sample is made available for testing, either before or after processing and storage.
The fresh amniotic fluid-derived cells, or the cultured MAFSC cells may be preserved so that the cells can be revived on demand. A preferred method is cryopreservation. One example of a suitable cryopreservation method is shown in Example 4. Typically, the surrounding fluid for preservation contains amniotic fluid. The use of amniotic fluid as part of the cryopreservation medium, rather than the use of other types of media or serum, allows for the cells to remain in the preferred undifferentiated form. Exposure of primary amniotic fluid (AF) cells or MAFSC cells to serum may cause the cells to become more susceptible to controlled differentiation, which may make them less suitable for future multipotent or pluripotent uses, once they are removed from storage. Preferably, the cryopreservation medium contains between about 10% and 50% amniotic fluid. More preferably, the cryopreservation medium contains between about 20% and 30% amniotic fluid. Most preferably, the cryopreservation medium contains about 24% to about 27% amniotic fluid. Preferably, the amniotic fluid is filtered. Most preferably, the filtration occurs through a 0.1 μm filter.
Another component of the cryopreservation medium is DMSO (dimethylsulfoxide). Preferably, DMSO is present at approximately 1% to 80% (V/V). More preferably, DMSO is present at approximately 5% to 30% (V/V). Most preferably, DMSO is present at approximately 8% to 12% DMSO.
The AF cells or MAFSCs can be stored indefinitely under liquid nitrogen. The cells can be kept for >100 years without the incidence of any damage: they can then be thawed, grown and differentiated as required. The cells are preferably frozen in the above described medium at a controlled rate. Preferably, this rate is from about 0.1° C./min to about 10° C./min. More preferably, the freezing rate is from about 0.2, 0.3, 0.4° C./min to about 4, 6, 8, or 9° C./min. Most preferably, the freezing rate is from about 0.5° C./min to about 2° C./min.
Frozen cells are then stored under liquid nitrogen until needed. The cells may be stored indefinitely, once frozen. Care should be taken to prevent the possibility of accidental thawing or warming of the frozen cells at any time during their storage period. In some embodiments of the invention, the cells may be preserved by methods other than cryopreservation.
Typing of Amniotic Fluid-Derived Cell Samples
In some embodiments of this invention, the amniotic fluid-derived cells can be further classified according to certain identifying features, such as by HLA typing, either before or after processing and storage. The term “type or “typing” refers to any characteristics of an amniotic fluid-derived cell sample that may be relevant for any possible use of the sample. Determination of which tests are relevant and how to perform them is entirely conventional and will change with technological developments. Typing also includes any method that identifies a stem cell product in such a way that the stem cell sample may be matched to a certain individual. For the purposes of this invention, matching indicates that the stem cell sample is suitable for transplantation into a specific individual.
The type information may include, for example, genotype or phenotype information. Genotype information may refer to a specific genetic composition of a specific individual organism, for example, whether an individual organism has one or more specific genetic variants up to all the variations in that individual's genome, for example, whether the individual is a carrier of genetic variations that influence disease or the HLA type of that individual. Phenotype information may include any observable or measurable parameter.
In some embodiments of the invention, the amniotic fluid-derived cells may be typed using HLA typing methods. For example, stem cells can be typed using the high-throughput HLA typing-methods described in U.S. Pat. No. 6,670,124, which is incorporated by reference herein in its entirety. A high throughput HLA typing method may include obtaining a biological sample containing template nucleic acid from a subject, amplifying the template nucleic acid with labeled HLA allele-specific primers, hybridizing the amplification products with immobilized HLA locus-specific capture oligonucleotides and using detection methods to determine the HLA genotype of the subject.
Other typing methods may be used. One typing method for HLA identification purposes is restriction fragment length polymorphism analysis. Restriction fragment length polymorphism analysis relies upon the strong linkage between allele-specific nucleotide sequences within the exons that encode functionally significant HLA class II epitopes. Another method, PCR-SSO, relies upon the hybridization of PCR amplified products with sequence-specific oligonucleotide probes to distinguish between HLA alleles (Tiercy et al., 1990, Blood Review 4: 9-15, Saiki et al., 1989, Proc. Natl. Acad. Sci., U.S.A. 86: 6230-6234; Erlich et al. (1991) Eur. J. Immunogenet. 18(1-2): 3355; Kawasaki et al. (1993) Methods Enzymol. 218:369-381), each of which is incorporated by reference herein in its entirety.
Another molecular typing method that can be used in the present invention, PCR-SSP, uses sequence specific primer amplification (Olerup and Zetterquist (1992) Tissue Antigens 39: 225-235, which is incorporated by reference herein in its entirety). The SSCP-Single-Stranded Conformational Polymorphism method may also be used. These and other standard techniques for HLA typing are known in the art, e.g., DNA typing or serological and cellular typing (Terasaki et al., 1964, Nature, 204:998, which is incorporated by reference herein in its entirety).
In some embodiments of the invention, in order to allow for the availability of cells which can be used for any individual, even if those who do not have stored amniotic fluid-derived cell samples, many amniotic fluid-derived cell samples can be banked that possess a range of genetic characteristics and that display a range of antigens to allow for sufficient matching of HLA specificities for the use by any potential recipient.
Organizing the Amniotic Fluid-Derived Cell Samples
This invention also provides methods of recording the amniotic fluid-derived cell samples so that when a stem cell sample needs to be located, it can be easily retrieved. Any indexing and retrieval system can be used to fulfill this purpose. Any suitable type of storage system can be used so that the stem cells can be stored. The amniotic fluid-derived cell samples can be designed to store individual samples, or can be designed to store hundreds, thousands and even millions of different amniotic fluid-derived cell samples.
The stored amniotic fluid-derived cell samples can be indexed for reliable and accurate retreival. For example, each sample can be marked with alphanumeric codes, bar codes, or any other method or combinations thereof. There may also be an accessible and readable listing of information enabling identification of each stem cell sample and its location in the bank and enabling identification of the source and/or type of stem cell sample, which is outside of the bank. This indexing system can be managed in any way known in the art, e.g., manually or non-manually, e.g. a computer and conventional software can be used.
In some embodiments of the invention, the amniotic fluid-derived cell samples are organized using an indexing system so that the sample will be available for the donor's use whenever needed. In other embodiments of the invention, the amniotic fluid-derived cell samples can be utilized by individuals other than the original donor. Once recorded into the indexing system, the amniotic fluid-derived cell sample can be made available for matching purposes, e.g., a matching program will identify an individual with matching type information and the individual will have the option of being provided the matching stem cell sample.
The storage banking system can comprise a system for storing a plurality of records associated with a plurality of individuals and a plurality of amniotic fluid-derived cell samples. Each record may contain type information, genotypic information or phenotypic information associated with the stem cell samples or specific individuals. In a specific embodiment, the system will include a cross-match table that matches types of the stem cell samples with types of individuals who with to receive a stem cell sample.
In a particular embodiment, the database system stores information for each stem cell sample in the bank. Certain information is stored in association with each sample. The information may be associated with a particular donor, for example, an identification of the donor and the donor's medical history. Alternatively, a stem cell sample may be anonymous and not associated with a specific donor. Alternatively, or additionally, the information may be sample type information. For example, the information might include the volume of the stem cell sample or the total nucleated cells count in the product. The stored information may also include match and typing information. For example, each stem cell sample may be HLA typed and the HLA type information may be stored in association with each sample. The information stored may also be availability information. The information stored with each sample is searchable and identifies the sample in such a way that it can be located and supplied to the client immediately.
Accordingly, Embodiments of the invention utilize computer-based systems that contain information such as the donor, date of submission, type of cells submitted, types of cell surface markers present, genetic information relating to the donor, or other pertinent information, and storage details such as maintenance records and the location of the stored samples, and other useful information.
The term “a computer-based system” refers to the hardware, software, and any database used to store, search, and retrieve information about the stored cells. The computer-based system preferably includes the storage media described above, and a processor for accessing and manipulating the data. The hardware of the computer-based systems of this embodiment comprise a central processing unit (CPU) and a database. A skilled artisan can readily appreciate that any one of the currently available computer-based systems are suitable.
In one particular embodiment, the computer system includes a processor connected to a bus that is connected to a main memory (preferably implemented as RAM) and a variety of secondary storage devices, such as a hard drive and removable medium storage device. The removable medium storage device can represent, for example, a floppy disk drive, a DVD drive, an optical disk drive, a compact disk drive, a magnetic tape drive, etc. A removable storage medium, such as a floppy disk, a compact disk, a magnetic tape, etc. containing control logic and/or data recorded therein can be inserted into the removable storage device. The computer system includes appropriate software for reading the control logic and/or the data from the removable medium storage device once inserted in the removable medium storage device. Information relating to the amniotic fluid-derived cells can be stored in a well known manner in the main memory, any of the secondary storage devices, and/or a removable storage medium. Software for accessing and processing these sequences (such as search tools, compare tools, etc.) reside in main memory during execution.
As used herein, “a database” refers to memory that can store any useful information relating to the amniotic fluid-derived cell collections and the donors. Additionally, a “database” refers to a memory access component that can access manufactures having recorded thereon information relating to the amniotic fluid-derived cell collections.
The data relating to the stored amniotic fluid-derived cells can be stored and manipulated in a variety of data processor programs in a variety of formats. For example, the data can be stored as text in a word processing file, such as Microsoft WORD or WORDPERFECT, an ASCII file, a html file, or a pdf file in a variety of database programs familiar to those of skill in the art, such as DB2, SYBASE, or ORACLE.
A “search program” refers to one or more programs that are implemented on the computer-based system to search for details or compare information relating to the cryopreserved samples within a database. A “retrieval program” refers to one or more programs that can be implemented on the computer-based system to identify parameters of interest in the database. For example, a retrieval program can be used to find samples that fit a particular profile, samples having specific markers or DNA sequences, or to find the location of samples corresponding to particular individuals.
The amniotic fluid-derived cell samples of the invention may be transported to and from a cell storage facility, interim facility or processing area by methods known in the art. Storage of the amniotic fluid-derived cell samples may be short term or long term. In some embodiments, the stored cells may be cryogenically preserved but any storage method suitable for long term storage may be used, such as, for example, the addition of amino acids, inosine, adenine, or other compounds to the cells. Any storage method may be used in this invention providing that the stored product retain viability for the therapeutic or other purposes.
There is no upper limit on the number of amniotic fluid-derived cell samples that can be stored in one cell bank. In one embodiment, hundreds of stem cell products from different individuals will be stored at one bank or storage facility. In another embodiment, up to millions of products may be stored in one storage facility. A single storage facility may be used to store amniotic fluid-derived cell samples, or multiple storage facilities may be used.
In some embodiments of the present invention, the storage facility may have a means for any method of organizing and indexing the stored cell samples, such as, for example, automated robotic retrieval mechanisms and cell sample manipulation mechanisms. The facility may include micromanipulation devices for processing such amniotic fluid-derived cell samples. Known conventional technologies can be used for efficient storage and retrieval of the amniotic fluid-derived cell samples. Exemplary technologies include but are not limited to Machine Vision, Robotics, Automated Guided Vehicle System, Automated Storage and Retrieval Systems, Computer Integrated Manufacturing, Computer Aided Process Planning, Statistical Process Control, and the like. Less sophisticated storage facilities may be used as well, such as, for example, large areas maintained at appropriate temperatures having numerous racks on which are indexed and stored the amniotic fluid-derived cell samples of the invention.
Potential Recipients of the Amniotic Fluid-Derived Cells
The type information or other information associated with the individual in need of a amniotic fluid-derived cell sample may be recorded into a system that can be used to identify an appropriate matching stem cell product, such as, for example, a database system, an indexing system, and the like. Once recorded in the system, a match can be made between the type of the individual and a donor amniotic fluid-derived cell sample. In preferred embodiments, the donor sample is from the same individual as the individual in need of the sample. However, similar but not identical donor/recipient matches can also be used. The matching amniotic fluid-derived cell sample is available for the individual possessing the matching type identifier. In one embodiment of this invention, the individual's identification information is stored in connection with the cell sample. In some embodiments, the matching process occurs around the time of harvesting the sample, or can occur at any time during processing, storage, or when a need arises. Accordingly, in some embodiments of the invention, the matching process occurs before the individual is in actual need of the amniotic fluid-derived cell sample.
When the amniotic fluid-derived cell sample is needed by an individual, it may be retrieved and made available for research, transplantation or other purposes within minutes, if desired. The stem cell sample may also be further processed to prepare it for transplantation or other needs.
Thawing the Banked Cells and Use of the Thawed Cells
When the cells are to be used, they can be thawed under controlled conditions. An example of one suitable method is shown in Example 8. Preferably, the thawing is performed at about 37° C. A water bath set at 37° C. may be used for this purpose.
The thawed samples can then be tested for viability and growth characteristics. Typically, over 99% viability is attained. The cells can be grown in any suitable medium, once the DMSO is diluted to less than about 1% of the cell culture volume. The growth properties, viability, karyotype and differentiation ability of frozen and thawed cells were found to be identical to fresh AF cells and to MAFSC cells upon freezing, respectively.
It was found that the previously stored, thawed cells could be grown and differentiated as if they had not been frozen. Therefore, once thawed, the cells can be used for creating cultures of undifferentiated cells, or for creating differentiated cell types or tissue types as disclosed herein and in co-pending U.S. patent provisional application Ser. No. 60/495,437, which is incorporated by reference herein in its entirety.
The thawed MAFSCs may be grown in an undifferentiated state for as long as desired, and can then be cultured under certain conditions to allow progression to a differentiated state. By “differentiation” is meant the process whereby an unspecialized cell acquires the features of a specialized cell such as a heart, liver, muscle, pancreas or other organ or tissue cell. The MAFSCs, when cultured under certain conditions, have the ability to differentiate in a regulated manner into three or more subphenotypes. Once sufficient cellular mass is achieved, cells can be differentiated into endodermal, mesodermal and ectodermal derived tissues in vitro and in vivo. This planned, specialized differentiation from undifferentiated cells towards a specific cell type or tissue type is termed “directed differentiation.” Examples of such cell types that may be prepared from MAFSCs using directed differentiation include but are not limited to fat cells, cardiac muscle cells, epithelial cells, liver cells, brain cells, blood cells, neurons, or glial cells.
General methods relating to stem cell differentiation techniques that may be useful for differentiating the MAFSCs of this invention can be found in general texts such as: Teratocarcinomas and embryonic stem cells: A practical approach (E. J. Robertson, ed., IRL Press Ltd. 1987); Guide to Techniques in Mouse Development (P. M. Wasserman et al. eds., Academic Press 1993); Embryonic Stem Cell Differentiation in vitro (M. V. Wiles, Meth. Enzymol. 225:900, 1993); Properties and uses of Embryonic Stem Cells: Prospects for Application to Human Biology and Gene Therapy (P. D. Rathjen et al., Reprod. Fertil. Dev. 10:31, 1998); and in Stem cell biology (L. M. Reid, Curr. Opinion Cell Biol. 2:121, 1990), each of which is incorporated by reference herein in its entirety.
Differentiation agents, maturation agents, or maturation factors may be useful to allow progression to certain cell types. Examples of differentiation agents, that may be used include but are not limited to agents, such as N-butyrate, which are useful for differentiating embryonic stem cells to liver cells are described in U.S. Pat. No. 6,506,574, to Rambhatla et al. Optionally, maturation agents, or maturation factors, such as, for example, growth factors, peptide hormones, cytokines, ligand receptor complexes, corticosteroids, and even organic solvents like DMSO have been found to effect differentiation of embryonic stem cells (U.S. Pat. No. 6,506,574, which is incorporated by reference herein in its entirety.
Treatment of Individuals Using Amniotic Fluid-Derived Cells that have been Thawed from a Cell Bank
The isolated amniotic fluid-derived cells or their derivatives may be used to treat diseases in humans or animals. As used herein the term “treat” or “treatment” refer to both therapeutic treatment and prophylactic or preventative measures, wherein the object is to prevent, slow down (lessen), or reverse an undesired physiological change or disorder. The term “treat” also refers to the characterization of the type or severity of disease which may have ramifications for future prognosis, or need for specific treatments. For purposes of this invention, beneficial or desired clinical results include, but are not limited to, alleviation of symptoms, diminishment of extent of disease, stabilized (i.e., not worsening) state of disease, delay or slowing of disease progression, amelioration or palliation of the disease state, and remission (whether partial or total), whether detectable or undetectable. “Treatment” can also mean prolonging survival as compared to expected survival if not receiving treatment. Those in need of treatment include those already with the condition or disorder as well as those prone to have the condition or disorder or those in which the condition or disorder is to be prevented.
To treat a human or animal in need of treatment, the amniotic fluid-derived cells can be either regenerated into segments of a desired tissue, then transplanted into the patient, or can be regenerated into a whole tissue that will be used to replace the failing tissue, or can be injected into a tissue of interest as whole cells, where they will regenerate at the injected location.
The banked amniotic fluid-derived cells may be used in the individual's postnatal life for purposes such as regenerative medical attention (as shown in Examples 8 and 9) or for cosmetic purposes. The banked cells will be readily available to prepare replacement tissue or cells as needed. Additionally, the amniotic fluid-derived cells and tissues derived from amniotic fluid-derived cells can also be shared with individuals of similar, but not necessarily identical genetic make-up. A directed search of the database information can be used to find samples of similar but not necessarily identical genetic make-up in situations where individuals of similar genetic background are not known or are not available.
It may be possible to replace any type of failing tissue with amniotic fluid-derived cells. Accordingly, amniotic fluid-derived cells that have been retrieved from a cell bank system may be differentiated into tissues such as liver, endocrine tissues, lung, blood cells, neuronal or astroglial cells, or others, which may then be used for transplantation to cure or treat diseases. Examples of tissues which may be (at least partially) replaced include, but are not limited to pancreatic tissue or cells, lung tissue, heart tissue, ocular tissue, nerve tissue, brain tissue, muscle tissue, skin, or others.
Examples of diseases that may be treated with amniotic fluid-derived cell-derived cells or tissues include but are not limited to cirrhosis of the liver, pancreatitis, diabetes, Parkinson's disease, spinal cord injury, stroke, burns, heart disease, certain types of cancer, osteoarthritis, rheumatoid arthritis, leukemia, lymphoma, genetic blood disorders, Examples of diseases that can be treated with amniotic fluid-derived cell-derived stem cells include but are not limited to Acute Lymphoblastic Leukemia, Acute Myelogenous Leukemia, Acute Biphenotypic Leukemia, and Acute Undifferentiated Leukemia; Chronic Myelogenous Leukemia, Chronic Lymphocytic Leukemia, Juvenile Chronic Myelogenous Leukemia, Juvenile Myelomonocytic Leukemia, Refractory Anemia, Refractory Anemia with Ringed Sideroblasts, Refractory Anemia with Excess Blasts, Refractory Anemia with Excess Blasts in Transformation, Chronic Myelomonocytic Leukemia, Aplastic Anemia, Fanconi Anemia, Paroxysmal Nocturnal Hemoglobinuria, Pure Red Cell Aplasia, Acute Myelofibrosis, Agnogenic Myeloid Metaplasia, myelofibrosis, Polycythemia Vera, Essential Thrombocythemia, Non-Hodgkin's Lymphoma, Hodgkin's Disease, Chediak-Higashi Syndrome, Chronic Granulomatous Disease, Neutrophil Actin Deficiency, Reticular Dysgenesis, Mucopolysaccharidoses, Hurler's Syndrome, Scheie Syndrome, Hunter's Syndrome, Sanfilippo Syndrome, Morquio Syndrome, Maroteaux-Lamy Syndrome, Sly Syndrome, Beta-Glucuronidase Deficiency, Adrenoleukodystrophy, Mucolipidosis II, Krabbe Disease, Gaucher's Disease, Niemann-Pick Disease, Wolman Disease, Metachromatic Leukodystrophy, Familial Erythrophagocytic Lymphohistiocytosis, Histiocytosis-X, Hemophagocytosis, Inherited Erythrocyte Abnormalities, Beta Thalassemia Major, Sickle Cell Disease, Inherited Immune System Disorders, Ataxia-Telangiectasia, Kostmann Syndrome, Leukocyte Adhesion Deficiency, DiGeorge Syndrome, Bare Lymphocyte Syndrome, Omenn's Syndrome, Severe Combined Immunodeficiency, Common Variable Immunodeficiency, Wiskott-Aldrich Syndrome, X-Linked Lymphoproliferative Disorder, Other Inherited Disorders, Lesch-Nyhan Syndrome, Cartilage-Hair Hypoplasia, Glanzmann Thrombasthenia, Osteopetrosis, Inherited Platelet Abnormalities, Amegakaryocytosis, Congenital Thrombocytopenia, Plasma Cell Disorders, Multiple Myeloma, Plasma Cell Leukemia, Waldenstrom's Macroglobulinemia, Breast Cancer, Ewing Sarcoma, Neuroblastoma, Renal Cell Carcinoma, brain disorders such as Alzheimer's disease, and the like (see, for example, hypertext transfer protocol (http) on the world wide web at the following link: marrow.org/index.html, which is incorporated by reference herein in its entirety).
Genetic Modification of MAFSCs before or after Banking
MAFSCs or MAFSC-derived cells may also be genetically modified by transduction with any suitable gene of interest, as shown in Example 10. General techniques useful to genetically modify the MAFSC cells (or their derivatives) can be found, for example, in standard textbooks and reviews in cell biology, tissue culture, and embryology. Methods in molecular genetics and genetic engineering are described, for example, in Molecular Cloning: A Laboratory Manual, 2nd Ed. (Sambrook et al., 1989); Oligonucleotide Synthesis (M. J. Gait, ed., 1984); Animal Cell Culture (R. I. Freshney, ed., 1987); the series Methods in Enzymology (Academic Press, Inc.); Gene Transfer Vectors for Mammalian Cells (I. M. Miller & M. P. Calos, eds., 1987); Current Protocols in Molecular Biology and Short Protocols in Molecular Biology, 3rd Edition (F. M. Ausubel et al., eds., 1987 & 1995); and Recombinant DNA Methodology II (R. Wu ed., Academic Press 1995).
Transduction of MAFSC cells can be accomplished by each of many techniques, DNA or RNA gene/sequence insertion of a suitably promoted gene construct, electroporation of said genes, infection by retroviral, lentiviral or other viral vector constructs encoding a gene of interest, mechanical gene introduction or the transfer by any means of specific protein, glycoprotein or phosphoprotein entities by any of a number of general techniques used for such purpose. The nucleic acid molecule of interest can be stably integrated into the genome of the host MAFSC cell, or the nucleic acid molecule and can also be present as an extrachromosomal molecule, such as a vector or plasmid. Such an extrachromosomal molecule can be auto-replicating. The term “transfection,” as used herein, refers to a process for introducing heterologous nucleic acid into the host MAFSC or MAFSC-derived cell or tissue. A transfected MAFSC cell refers to a MAFSC cell into which a heterologous nucleic acid molecule has been introduced. One example of a useful genetic modification of a MAFSC cell was the insertion of the “TERT” gene (telomerase reverse transcriptase). MAFSC Cells that have had the Tert gene transduced by retroviral gene transduction expressed this gene to high levels and had acquired an immortal phenotype, i.e. they did not senesce after >200 population doublings. Further, genetic modification of MAFSC cells can be used for purposes of propagation of stable non-differentiated cells, for the purpose of accomplishing stable or transient MAFSC cell differentiation or for gene therapy purposes, such as the administration of a gene encoding a functional protein product to an individual that lacks a functional copy of a gene of interest. If desired, MAFSC cells or their derivatives can also be genetically modified to inhibit the expression of certain genes, using gene manipulation methods known in the art.
It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the spirit of the present invention. A more complete understanding can be obtained by reference to the following specific examples which are provided herein for purposes of illustration only and are not intended to limit the scope of the invention.
Approximately 2 to 5 ml of fresh amniotic fluid was harvested from women undergoing routine amniocentesis at 16 to 21 weeks of pregnancy (2nd trimester). Second trimester amniotic fluid contained approximately 1-2×104 live cells per ml. The cells were pelleted in a clinical centrifuge and resuspended in 15 ml “MAFSC” medium. MAFSC medium was composed of low glucose Dulbecco Modified Eagle's Medium (GIBCO, Carlsbad, Calif.) and MCDB 201 medium (SIGMA, Saint Louis, Mo.) at a one to one ratio and contained 2% Defined Fetal Calf Serum (HYCLONE, Logan, Utah), 1× insulin-transferrin-selenium, linoleic-acid-bovine-serum-albumin (ITS+1, SIGMA), 1 nanomolar dexamethasone (Sigma), 100 μm ascorbic acid 2-phosphate (Sigma), 4 μm/ml gentamycin, 10 ng/ml of rhEGF (R&D Systems, Minneapolis, Minn.), 10 ng/ml rrPDGF-BB (R&D) and 10 ng/ml rhFGF-basic (R&D). The wells of 6-well culture dishes were prepared for cell plating by coating for one hour at room temperature with 2.5 ml of fibronectin (stock of 10 μg fibronectin/ml of sterile water) immediately prior to cell plating. The fibronectin solution was removed prior to cell plating and the wells were not washed after removal of the fibronectin solution. The cells were then seeded in 2.5 ml of medium in each well.
The cells in MAFSC culture appeared under the inverted phase microscope as large suspension cells that divided on average once every 4 days, but ceased dividing 8-12 days after seeding. The growth medium of MAFSC cultures was changed with complete MAFSC medium every two days making sure to not lose the suspended cells. After 8-10 days, small numbers of adherent cells emerged which grew into large colonies of >105 cells in 14-15 days. On average, 0-1 adherent colonies grew out per 2×104 live cells seeded. Hence, a sample of 5 ml of fresh amniotic fluid gave rise to 3-5 adherent cell colonies, resulting in a single colony/clone in the majority of the wells of 6-well cell culture clusters.
Cells were transferred to successively larger fibronectin-coated flasks/vessels. To perform cell transfer, the cells were grown to a subconfluent state of approximately 40% confluence and were detached with 0.25% Trypsin-EDTA and replated at a 1:3 or 1:12 dilution under the same culture conditions.
Cultured amniotic fluid-derived cells were tested for cell surface and differentiation markers and were karyotyped. These cells were found to be immortal or near-immortal and were named Multipotent Amniotic Fetal Stem Cells (MAFSC).
All of >80 amniotic fluid sample harvests of 5 ml gave rise to at least one adherent MAFSC colony and continuous culture. The majority of sample harvests gave rise to 3-4 individual clones. Among the individual clones, different colonies/cultures had diverse colony morphologies, as shown in FIG. 1. Some cultures had a flat, epihelial morphology (FIG. 1A). Others had a fibroblastic morphology (FIGS. 1B, 1C). Both the epithelioid and the fibroblastic classes of cultures senesced after ˜60 population doublings (PD), yielding a maximum of 1018 cells, unless the cells were immortalized by the expression of the human TERT (telomerase) gene that maintained the length of the cells' telomeres. Indeed, mortal MAFSC cultures have been immortalized at low (PD 15-25) transfer numbers by infection with an amphotropic high titer retroviral vector expressing the human TERT gene. MAFSC cultures immortalized with TERT have not senesced after >220 population doublings. Thus, the TERT-modified MAFSC cultures were immortal, though only after genetic modification which may not be the advantaged way to derive human stem cell strains.
About half of the amniotic fluid samples gave rise to MAFSC clones/cultures that behaved like immortal cell lines, as shown in FIGS. 2A and 2B. These cultures grew vigorously, with a doubling time of 28 hours. When confluent, the cells piled up in multilayered fashion and numerous round, semi-detached cells grew on top of a swirling, non-contact-inhibited layer of cells. These aggressive cultures expressed the telomerase gene/protein. The cells were cloneable into single cell clones and are non-senescing. These vigorously growing MAFSC lines expressed very high levels of a set of cell surface determinants known to be present on non-differentiated human Embryo Stem Cells (hES) and expressed a set of surface determinants known to be associated with non-differentiated human Mesenchymal Stem Cells (MSC). MAFSC cells did not express markers characteristic of hematopoietic cells, e.g. CD45 and CD34, see FIGS. 3 and 4, which show flow cytometry examples of one such vigorous MAFSC line, #111a.
Cells were prepared for FACS analysis by trypsinizing to remove them from the tissue culture flask, washing in buffer, HBSS, 2% BSA, 0.1% sodium azide, then resuspended in 100 μL of the same buffer. For intracellular antigens (i.e. Oct-4), the cells were fixed and permeablized using Beckman-Coulter IntraPrep reagents, as suggested by the manufacturer. Primary antibodies specific for the indicated cell-surface or intracellular marker were added at a 1:10 dilution and incubated for 30 minutes at room temperature, then washed. For samples using primary antibodies that were not fluorescently-conjugated, the cells were then resuspended in 250 μL of buffer and the appropriate fluorescent-labeled secondary antibody was added at a 1:250 dilution and incubated for 30 minutes at room temperature. Labeled cells were washed and resuspended in buffer or 1% paraformaldehyde for analysis by a FACSCalibur flow cytometer. The data obtained from this analysis were plotted as the x-axis being the number of cells analyzed per point and the y-axis indicating the logarithm of fluorescent intensity of the antibody-labeled cells. The fluorescence was compared to control cells that were not labeled with antibody, to discount any background fluorescence. The percent indicated was the fraction of cells that were positive for the specific antibody-labeled antigen. The level of antibody label (X-axis) is proportional to the concentration of the specific antigen present on the cells.
MAFSC lines expressed very high levels of a set of cell surface determinants known to be present on non-differentiated human Embryo Stem Cells (hES) and expressed a set of surface determinants known to be associated with non-differentiated human Mesenchymal Stem Cells (MSC). MAFSC cells did not express markers characteristic of hematopoietic cells, e.g. CD45 and CD34, see FIGS. 3 and 4, which show flow cytometry examples of one such vigorous MAFSC line, #111a. The flow cytometry was performed as described above in Example 3.
Mass cultures of the MAFSC cells strain 111a were characterized by very high expression of the globoseries glycolipid antigens SSEA3 (96%), SSEA4 (96%), the lack of expression of a lactoseries oligosaccharide antigen, SSEA1, the expression of the keratin sulphate-related antigens Tra-1-60 (71%) and Tra-1-81 (82%) and the tissue non-specific alkaline phosphatase-related antigen Tra-2-54 (63%), FIG. 3. The expression (or lack of expression, SSEA1) of these antigens is expressly exhibited by pluropotential, undifferentiated human embryo stem cells in which the expression of these antigens is lost (or gained, SSEA1) by the induction of differentiation with retinoic acid (Draper J S, Pigott C, Thompson J A, Andrews P W. 2002 Journal of Anatomy 200: 249-258). MAFSC cells expressed high levels of HLA Class I but not of HLA Class II, low levels of CD 117 (c-kit ligand) and Stro-1, FIG. 3.
In addition to the embryo stem cell markers shown in FIG. 3 and discussed in Table 1, MAFSC cells (such as, for example the MAFSC 111 a line), expressed high levels of the antigen CD13 (99.6%) aminopeptidase N, CD44 (99.7%) hyaluronic acid-binding receptor, CD49b (99.8%) collagen/laminin-binding integrin alpha2, and CD105 (97%) endoglin. This set of cell surface antigens is found on human mesenchymal stem cells but not normally on human embryo stem cells (M F Pittinger et al., Science 284:143-147, 1999; S Gronthos et al., J Cell Physiol. 189:54-63, 2001). Hence, the amniotic fluid-derived MAFSC cells, grown and propagated as described here, represent a novel class of human stem cells that combined the characteristics of hES cells and of hMSC cells and can be expected to differentiate into many diverse directions.
The amniotic fluid-derived stem cells also expressed the transcription factor OCT-4. The human embryonic stem cell markers typically found on MAFSC cells are shown in Table 1 and are data obtained for MAFSC cells, clone 111a, cultured for >40 population doublings in MAFSC culture medium. The markers typically displayed by long term MAFSC cells are compared with the same markers found on fresh amniotic fluid-derived cells, “AES”, and with various control cells, the human embryonic carcinoma cell line NTERA-4; amniotic-fluid-derived, long-term fibroblasts, MY-TERT, immortalized by the human telomerase reverse transcriptase gene, TERT; and normal human foreskin fibroblasts, HFF. Expression of the various markers is further described in co-pending U.S. Patent Application filed Aug. 13, 2004, entitled, “Multipotent Amniotic Fetal Stem Cells.”
Both fresh amniocentesis-derived cells and cultured MAFSC cells were cryopreserved for banking purposes. Samples of amniotic fluid ranging from 2 to 5 ml were harvested. The cells were centrifuged to remove excess amniotic fluid. The cells were then frozen in medium containing 10% dimethyl sulfoxide and 25% fresh, filtered (0.10 micron) amniotic fluid (DMSO/AF freezing medium). Alternatively, the cells were grown to produce MAFSC cultures, which were then frozen as above. The fresh amniocentesis-derived cells and cultured MAFSC cells were frozen in DMSO/AF freezing medium in a controlled-rate liquid nitrogen freezer at 1° C./min. Frozen samples were stored under liquid nitrogen in freezing ampoules.
To assure the availability of stem cells transplantable into all or into a majority of potential recipients, stem cells will be banked that possess a range of genetic characteristics and that display a range of antigens, for example a range of human leukocyte antigens (HLA antigens). Following widely recognized and universally applied transplantation methodologies in human bone marrow transplantation and in human organ transplantation, matching of ten HLA specificities is generally sufficient to achieve full and problem-free transplantations. The development of an amniocyte-derived stem cell bank facilitates the cryopreservation of hundreds or of thousands of lines possessing finely-mapped transplantation specificities for the accomplishment of routine stem cell transplantation into a majority of potential subjects.
The cryopreserved cells may be listed in a searchable database. Information such as genetic background of the stored cells, familial data, date of submission, suspected or known genetic diseases of individuals or relatives, etc., may be included, for example. When an individual has a medical problem that can be alleviated or reversed by administering cells derived from the thawed cryopreserved cells, the database can be searched for pertinent information. A suitable sample can then be chosen for thawing, cell proliferation, differentiation, and administration to the individual.
Cell thawing was done rapidly in a 37° C. water bath resulting in the recovery of >99% of the frozen AF and MAFSC cells. Thawed cells were then grown by being immediately diluted 10-fold to reduce the concentration of DMSO to <1%. The percent viability of the cells was determined. When the amniotic fluid cells are properly frozen, as is the state of the art, and they are rapidly thawed, there is essentially no cell death: viability is close to 99%, the cells' growth behavior in MAFSC cultures is also not affected by cryopreservation and thawing.
The viability of cryopreserved cells was equal to that of fresh amniotic fluid cells. A typical fresh 2nd trimester amniocentesis sample had a viablility of 30-50%, depending on the exact number of weeks of the pregnancy: earlier harvests were more highly viable. At later times in the pregnancy, e.g. 35 weeks, the viability of freshly removed amniotic cells is about 10%, however the absolute number of viable cells in a sample is roughly equal to that found in 16-18 week amniocentesis harvests, namely 1-2×104 cells/ml. At later times in the pregnancy more dead cells accumulate, while the absolute number of live cells stays similar.
The time between the harvesting of the amniotic cells to the time of seeding the cells in MAFSC culture medium or to the time of cryopreserving the cells was important. A delay of 24 hours in seeding/growing or in cryopreserving the cells reduced the probability of success in growing MAFSC stem cells by ˜90%. Hence, speedy cryopreservation of amniotic fluid samples, within 2-4 hours of amniocentesis drawing, was crucial in the success of growing MAFSC stem cells from the sample. Interestingly, the concentration of viable cells did not diminish significantly by delaying the amniotic fluid sample procedures (seeding or freezing) by keeping the samples at room temperature in their natural fluid. The number of resultant stem cells, however, was significantly reduced, by ˜90%. Therefore, the MAFSC stem cells in an amniotic fluid sample were more fragile than the bulk of the cells in the harvest.
Cryopreserved cells were revived, cultured, and differentiated into various cell types, such as neural cells, adipogenic cells, and chondrogenic cells, as described in co-pending U.S. Patent Application filed Aug. 13, 2004, entitled, “Multipotent Amniotic Fetal Stem Cells,” which is incorporated by reference herein in its entirety.
Treatment of Diseases Using Transplantation of Differentiated MAFSCs
Cryopreserved MAFSCs that have been thawed from a cell bank system or MAFSC stem cells that have been grown from a cryopreserved amniotic fluid cell sample may be differentiated into various tissues, as needed. In one example, MAFSC stem cells can be differentiated into pancreatic beta cells that secrete insulin under the control of glucose prevalence. Beta cells or beta cells enveloped into pancreatic islets with or without scaffolding can be implanted at a suitable site in diabetic patients. In this way, the glucose responsive beta cells or reconstructed pancreatic islets can control the level of glucose in the diabetic patient. The availability of syngenetic (“own”) amniotic cells or the genetic matching of amniotic fluid-derived islet cells to a diabetic's transplantation antigen status thus facilitates the regulation of glucose concentration without the danger of ersatz-pancreatic rejection by the diabetic recipient.
Following MAFSC cell differentiation into the cells of interest, differentiated MAFSCs can be transplanted into a patient in need of treatment to promote bone marrow regeneration. MAFSC cells of suitable transplantation genotype, either the fetal-donor of origin of the cryopreserved amniotic cells or a transplantation antigen-matched recipient patient, are differentiated in vitro by state of the art methods into hematopoietic stem and/or progenitor cells, for example by methods similar to those described by Carotta et al., “Directed differentiation and mass cultivation of pure erythroid progenitors from mouse embryonic stem cells”, Blood 2004, May 27, prepublished online, DOI 10.1182. MAFSC cells differentiated into specific hematopoietic stem/progenitor cell types can then be used for transplantation by infusion into recipients in need of hematopoietic cell transplantation. The cryopreservation of millions of samples of amniotic fluid cells and the potential generation of multiple MAFSC stem cell lines of different transplantation specificities facilitates the preparation, by differentiation, of suitable hematopoietic stem/progenitor cells as a general bone marrow-transplantation resource. Genetically and antigenically matched hematopoietic stem/progenitor cell populations will induce minimal transplantation complications in the transplantation of patients requiring hematopoietic cell transplantation.
MAFSCs or MAFSC-derived cells may also be genetically modified either before or after the banking period, using any suitable means, such as cell transfection procedures. The nucleic acid molecule can be stably integrated into the genome of the host MAFSC cell, or the nucleic acid molecule and can also be present as an extrachromosomal molecule, such as a vector or plasmid. One example of a useful genetic modification of a MAFSC cell is the insertion of the “TERT” gene (human telomerase reverse transcriptase, GenBank Accession No. NM—003219). A vector suitable for mammalian transfection is prepared, containing a selectable marker gene and the gene encoding “TERT”, operably linked to a suitable promoter sequence. The vector is used to stably transfect a mammalian MAFSC cell. Stably transfected cells are then selected using the selection agent corresponding to the selectable marker gene. Expression of TERT is then confirmed using antibody-based detection procedures. MAFSC Cells that are able to express this TERT sequence can be significantly expanded.
An individual in need of stem cells or stem cell products for treatment of a disease is identified. Type identifiers of the individual are identified. The database of amniotic fluid-derived cell banked samples is searched for donors with similar type identifiers. Further analysis is performed to confirm the similarity. The amniotic fluid-derived cell sample is retrieved, and the cells are revived. The cells are treated so as to expand and differentiate into the desired cell type, and are subsequently transplanted to the individual in need of treatment. The success of the treatment is ascertained at daily to monthly intervals. Using this method, the disease is successfully treated.
It will be appreciated that no matter how detailed the foregoing appears in text, the invention can be practiced in many ways. As is also stated above, it should further be noted that the use of particular terminology when describing certain features or aspects of the present invention should not be taken to imply that the broadest reasonable meaning of such terminology is not intended, or that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the invention with which that terminology is associated. Thus, although this invention has been described in terms of certain preferred embodiments, other embodiments which will be apparent to those of ordinary skill in the art in view of the disclosure herein are also within the scope of this invention. Accordingly, the scope of the invention is intended to be defined only by reference to the appended claims and any equivalents thereof. All documents cited herein are incorporated herein by reference in their entireties.