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Posted by Ellen on 08:20:03 2004/07/28
July 27, 2004 07:30 AM US Eastern Timezone
Geron Announces Publication Showing Human Embryonic Stem Cells Possess Unique Immune Properties
MENLO PARK, Calif.--(BUSINESS WIRE)--July 27, 2004--Geron Corporation (Nasdaq:GERN) announced today the publication of results demonstrating that human embryonic stem cells (hESCs) have unique immune-privileged properties, and suggesting the possibility that there may be reduced need for immunosuppression upon transplantation of cells derived from hESCs.
Transplantation of cells, tissues or organs from one individual to another is complicated by immune rejection of the transplanted tissue. The transplanted tissues express proteins known as major histocompatibility (MHC) antigens. The transplant recipient normally mounts a strong immune-based rejection response against those antigens, involving inflammation and infiltration by many immune cells, including T-cells. In many situations the recipient must receive immunosuppressive drugs to prevent immune rejection and to permit the transplanted tissue to engraft.
In the studies described in this report, published in the July issue of the journal Stem Cells, Dr. Mickie Bhatia of the Robarts Research Institute in London, Ontario and scientists at Geron demonstrate that undifferentiated hESCs transplanted in vivo, unlike other human cells, do not elicit certain immune responses that normally trigger graft rejection. In particular, the hESCs did not cause inflammatory cell infiltration when transplanted into mice. In in vitro experiments, neither undifferentiated hESCs nor partially differentiated hESCs induced proliferation of T-cells.
Moreover, transplanted undifferentiated hESCs were found to actively inhibit certain immune responses. Injection of hESCs into mice along with endotoxin, a strong stimulator of inflammation, did not produce the inflammatory granulocyte and lymphocyte infiltration that resulted from injection of endotoxin alone or endotoxin along with another type of human cell.
These observations were supported by in vitro studies showing that the undifferentiated hESCs could actively inhibit the potent T-cell responses that normally occur when human peripheral blood cells from two individuals are co-cultured. This inhibitory effect was found to be an intrinsic property of the hESCs themselves, and was not caused by some factor secreted by the hESCs.
"This work has major implications for hESC-based transplantation therapies," said Thomas B. Okarma, Ph.D., M.D., Geron's president and chief executive officer. "The studies indicate that undifferentiated hESCs can locally prevent immune rejection responses, while neither undifferentiated nor partially differentiated hESCs cause typical immune rejection responses. This may mean that undifferentiated hESCs, irradiated to prevent their proliferation, can be used to protect grafts of cells differentiated from hESCs. We are conducting further studies to determine if these immune-privileged properties are retained by more fully differentiated hESC-derived cells. In either case, it may be possible that hESC-derived grafts may require reduced or no immunosuppression."
Geron is a biopharmaceutical company focused on developing and commercializing therapeutic and diagnostic products for cancer based on its telomerase technology, and cell-based therapeutics using its human embryonic stem cell technology.
This news release may contain forward-looking statements made pursuant to the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Investors are cautioned that such forward-looking statements in this press release regarding potential applications of Geron's technologies constitute forward-looking statements that involve risks and uncertainties, including, without limitation, risks inherent in the development and commercialization of potential products, need for future capital and maintenance of our intellectual property rights. Actual results may differ materially from the results anticipated in these forward-looking statements. Additional information on potential factors that could affect our results and other risks and uncertainties are detailed from time to time in Geron's periodic reports, including the quarterly report on Form 10-Q for the quarter ended March 31, 2004.
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