The assignee for this patent, patent number 8637311, is
Reporters obtained the following quote from the background information supplied by the inventors: "Considerable interest has been generated in the field of regenerative medicine by recent work relating to the isolation and propagation of human stem cells from the early embryo. These cells have two very special properties: First, unlike other normal mammalian cell types, they can be propagated in culture almost indefinitely, providing a virtually unlimited supply. Second, they can be used to generate a variety of tissue types of interest as a source of replacement cells and tissues that are damaged in the course of disease, infection, or because of congenital abnormalities.
"Early work on pluripotent stem cells was done in mice (Robertson, Meth. Cell Biol. 75:173, 1997; and Pedersen, Reprod. Fertil. Dev. 6:543, 1994). Experiments with human stem cells have required overcoming a number of additional technical difficulties and compilations. As a result, technology for culturing and differentiating human pluripotent stem cells is considerably less advanced.
"Thomson et al. (U.S. Pat. No. 5,843,780; Proc. Natl. Acad. Sci.
"A significant challenge to the use of pluripotent stem cells for therapy is that they are traditionally cultured on a layer of feeder cells to prevent differentiation (U.S. Pat. No. 5,843,780; U.S. Pat. No. 6,090,622). According to Thomson et al. (Science 282:114, 1998), hPS cells cultured without feeders soon die, or differentiate into a heterogeneous population of committed cells. Leukemia inhibitory factor (LIF) inhibits differentiation of mouse ES cells, but it does not replace the role of feeder cells in preventing differentiation of human ES cells.
"International Patent Publication WO 99/20741 (
"International Patent Publication WO 01/51616 (
"New technology to facilitate growing and manipulating undifferentiated pluripotent stem cells would be a substantial achievement towards realizing the full commercial potential of embryonic cell therapy."
In addition to obtaining background information on this patent, NewsRx editors also obtained the inventors' summary information for this patent: "This disclosure provides an improved system for expanding primate pluripotent stem (pPS) cells. The technology allows the user to rapidly produce high-quality pPS cells for use in therapy are drug discovery, free of undesired contamination by cells of other species and other tissue types.
"Application of the technology involves introducing stem cells into a culture environment containing components described and exemplified in more detail in the sections that follow. Typically, the environment will contain a support structure, a culture medium, and one or more factors added to the medium that support proliferation of the pPS cells in an undifferentiated state. Exemplary support structures are made from isolated extracellular matrix components. Exemplary culture media comprise an isotonic buffer, a protein or amino acid source, and may also comprise nucleotides, lipids, and hormones. An exemplary factor for adding to the medium is a fibroblast growth factor. It has been discovered that sufficient FGF in a suitable medium is sufficient to maintain pPS cells in a substantially undifferentiated state through extended culture. Other factors listed in this disclosure can be added to improve the quality and expansion rate of the culture when desired.
"The culture environment can be essentially free of feeder cells, since feeder cells are not required to keep the pPS cells proliferating in an undifferentiated state. In this embodiment, the cells consist essentially of undifferentiated pPS cells, and progeny thereof that may have begun differentiation or adopted an altered phenotype. Since they are all derived from the same pPS cells, all of the cells in the culture will have the same genotype, which means that the cells have the same chromosomal DNA (plus or minus karyotype abnormalities or deliberate genetic alterations). This can be ascertained by demonstrating that essentially all the cells in the culture are derived from the same pPS cells. Included are mixed populations made by combining different lines of pPS cells and their progeny, as long as essentially each of the cells in the culture are progeny of one of the starting cell lines.
"An important virtue of this system is that there is no need to condition the medium before combining it with the stem cells. The skilled reader may wish to precondition the medium with other cell lines in advance, but the medium can be added 'fresh' to the pPS cells and still support proliferation without differentiation. This means that the medium has not been cultured with other cell types before being added to the pPS cell culture (either by direct substitution for spent medium, or in a gradual or continuous exchange system).
"Another virtue of the system is the ability to adjust conditions so that the cells expand more rapidly (as much as 11/2 times faster) than they do when cultured on feeder cells according to traditional techniques, or in conditioned medium. While the user need not expand the cells rapidly in order to use this invention, she has the option of growing the cells with a doubling time of as little as 24 hours.
"Using this culture system (optionally passaging the cells into new culture environments when required), populations of pluripotent stem cells can be obtained that are expanded 10-fold or more when compared with the starting population. Even after expansion, a high proportion of the cells are still undifferentiated, according to morphological characteristics, phenotypic markers, or the ability to differentiate into derivatives of the three embryonic germ layers (endoderm, mesoderm, and ectoderm).
"Embodiments of this invention include the culture environment in which the pPS cells are expanded and its use, the combined composition of the environment and the pPS cells, and various methods for expanding pPS cells using the reagents and techniques described in this disclosure. This system can be used with pPS cells of various types, exemplified by cells isolated or propagated from human blastocysts, such as established human embryonic stem cell lines and their equivalents.
"This system can be used to generate genetically altered pPS cells. The cells are transfected with a suitable vector for effecting the desired genetic alteration, such as a DNA-lipid complex. This is facilitated in the feeder-free culture systems of this invention. The genetically altered cell population can be expanded as already described, before or after genetic alteration and/or selection of the altered genotype.
"This system can also be used to generate differentiated cell types of various kinds. After the undifferentiated pPS cells are expanded to the desired number, they are caused to differentiate according to any of a variety of differentiation paradigms provided later in this disclosure. Differentiated populations can be obtained in which at least 95% of the cells represent the same tissue type or germ layer: for example, neural cells, hepatocytes, cardiomyocytes, mesenchymal cells, or osteoblasts.
"These and other aspects of the invention will be apparent from the description that follows."
For more information, see this patent: Mandalam, Ramkumar; Xu, Chunhui; Gold, Joseph D.; Carpenter,
Keywords for this news article include: Biotechnology, Genetics, Cell Line, Fibroblasts, Gene Therapy, Bioengineering, Cultured Cells, Stem Cell Research, Embryonic Stem Cells,
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