Studies Show Geron's Stem Cell Therapeutic for Spinal Cord Injury Produces Nerve Growth Factors.

Findings Published in Stem Cells and Development Indicate GRNOPC1 Promotes Survival and Regeneration of Neurons Damaged During Spinal Cord Injury 

MENLO PARK, Calif. -- Geron Corporation (Nasdaq: GERN) today reported that studies show GRNOPC1, the company's human embryonic stem cell (hESC)-based oligodendroglial progenitor therapeutic, produces multiple nerve growth factors, proteins that stimulate the survival and regeneration of neurons damaged during spinal cord injury.

Published in Stem Cells and Development (Vol. 15, Issue 6, 943-952), the studies conducted by Geron scientists describe a newly discovered neurotrophic effect that, in addition to the previously documented in vivo remyelinating activity of these cells (Journal of Neuroscience, 25 (19): 4694-4705, 2005), serves as a second mechanism of action that demonstrates the product's beneficial effects when injected into animal models of acute spinal cord injury.

"The work extends our knowledge of the multiple biological activities of GRNOPC1," stated Thomas B. Okarma, Ph.D., M.D., Geron's president and chief executive officer. "In addition to the remyelinating activity as previously reported, GRNOPC1 produces growth factors that can improve the survival and extension of neuronal circuitry in the spinal cord. The multiple functions of GRNOPC1 affirm the potential therapeutic utility of our cell-based approach to the repair of spinal cord injury and provide multiple mechanisms within a single therapy to achieve functional recovery."

In the published studies, GRNOPC1 was found to produce numerous neurotrophic factors, including transforming growth factor [eth]1 (TGF-[eth]1), transforming growth factor [eth]2 (TGF-[eth]2), activin A, midkine, vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF). These factors were all produced at physiologically active levels, and each has been reported to have trophic effects on neurons associated with the spinal cord.

In spinal cord injury, neuronal cell loss can occur not only as a result of the physical trauma of the injury itself, but also due to the oxidative and inflammatory reaction that subsequently occurs. The introduction of neurotrophic factors into the lesion site could increase neuronal survival, decrease dieback of neuronal axons and induce sprouting of new axons to allow formation of alternative circuitry.

The studies also demonstrate that neurotrophic factors produced by GRNOPC1 are biologically active. When culture medium used to grow GRNOPC1 was applied to adult rat sensory neurons, sprouts called "neurites" emerged from the rat neurons. Media that had not been exposed to GRNOPC1 stimulated significantly less neurite outgrowth.

"Our studies show that multiple neurotrophic factors are produced by GRNOPC1 that lead to neurite outgrowth," said R. Scott Thies, Ph.D., Geron's lead investigator on the work. "Depletion or inactivation of any single factor did not eliminate the neurotrophic activity exhibited by these cells."

Geron is developing first-in-class biopharmaceuticals for the treatment of cancer and degenerative diseases, including spinal cord injury, heart failure, diabetes and HIV/AIDS. The company is advancing an anticancer drug and a cancer vaccine that target the enzyme telomerase through multiple clinical trials. Geron is also the world leader in the development of human embryonic stem cell-based therapeutics, with its spinal cord injury treatment poised to be the first product to enter clinical development. For more information, visit www.geron.com.

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 technology constitute forward-looking statements that involve risks and uncertainties, including, without limitation, risks inherent in the development and commercialization of potential products, uncertainty of clinical trial results or regulatory approvals or clearances, need for future capital, dependence upon collaborators 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, 2006.