Geron Presents Data on Human Embryonic Stem Cell-based Therapy for Heart Failure.

MENLO PARK, Calif. -- Geron Corporation (Nasdaq:GERN) announced today the presentation of studies which show that functional cardiomyocytes can be differentiated from human embryonic stem cells (hESCs). Presented at the Cell Transplant Society Meeting in Boston, Geron scientists reported substantial improvements in differentiation methods and characterization of the cells. The company also reported early engraftment results from transplant studies in animal models.

In previous studies, Geron scientists and collaborators have shown that cardiomyocytes can be differentiated from hESCs and will graft into the left ventricular wall of normal healthy rats. The cardiomyocytes integrated into the heart muscle and underwent limited proliferation after injection.

In the newly presented work, Geron scientists described an improved method to produce cardiomyocytes with higher purity and maturity. The new protocol yields a cardiomyocyte population with a 20-fold increased expression of cardiomyocyte markers and greater than 65% purity. In collaboration with Dr. Charles Murry at the University of Washington, the cells were transplanted into normal rat hearts. Four weeks after transplant, the grafted cardiomyocytes had formed islands of human myocardium within the rat heart. "In the animals, this enriched cardiomyocyte population retained expression of normal cardiomyocyte markers," stated Joseph Gold Ph.D., lead Geron author of the work.

"This advance enables the next step, which is to transplant this improved cardiomyocyte population into rodents with infarcted hearts to demonstrate the utility of these cells to repair damaged heart muscle," stated Jane S. Lebkowski Ph.D., Geron's senior vice president of regenerative medicine.

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 human embryonic stem cell technologies involve risks and uncertainties, including, without limitation, risks inherent in the development and commercialization of potential products, reliance on collaborators, 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 September 30, 2004.