Geron Announces Presentation of Preclinical Studies on Human Embryonic Stem Cell-Based Treatment of Acute Spinal Cord Injury.

Business Editors/Health/Medical Writers

MENLO PARK, Calif.--(BUSINESS WIRE)--Nov. 13, 2003

Geron Corporation (Nasdaq:GERN) today announced the presentation of results demonstrating that the transplant of cells differentiated from human embryonic stem cells (hESCs) can result in functional improvement in animals with spinal cord injuries. This work provides proof of concept of the efficacy of hESC-based therapies in spinal cord injury.

In two presentations at the Society for Neurosciences Annual Meeting in New Orleans, Dr. Hans Keirstead and his colleagues from the University of California at Irvine detailed studies demonstrating that when hESC-derived oligodendroglial progenitors were transplanted into rats that had received a thoracic spinal cord contusion injury, statistically significant improvements in the ambulatory activity of the rats could be observed approximately one month later. In these blinded studies, animals showed evidence of improved weight-bearing capacity, paw placement, tail elevation and toe clearance activity compared to injured untreated animals. Control animals that received transplants of human fibroblasts instead of oligodendroglial progenitors showed little, if any improvement.

"These results are exciting. They show that cells derived from hESCs can have therapeutic efficacy in a model of human disease," stated Jane S. Lebkowski, Ph.D., Geron's vice president of regenerative medicine.

In these studies, the cells were transplanted directly into the spinal cord lesions seven days after injury. Dr. Keirstead found evidence of both increased oligodendrocyte-mediated myelination and some neural sprouting upstream of the lesion in the test animals. These observations were further supported by additional transplant studies from Dr. Keirstead's lab in which the oligodendroglial progenitors were implanted into the spinal cord of Shiverer mice, a mutant mouse that is deficient in myelin basic protein and hence lacks normal neuronal myelination. In those mice the researchers observed evidence of oligodendrocyte-mediated remyelination of nerve cell axons. No evidence of tumor formation from the transplanted cells or other adverse events was observed in any of these studies.

In a third presentation at the meeting, Dr. Keirstead and his colleagues presented data showing how hESCs can be differentiated in tissue culture to oligodendroglial progenitors, the precursors of oligodendrocytes. Oligodendrocytes are specialized neural cells that produce myelin, the protective sheath that insulates the axons of nerve cells allowing normal nerve impulse conduction. Oligodendrocytes also produce a variety of neurotropic factors which can induce the sprouting of nerve cells. In a spinal cord contusion injury, neurons that are spared during the initial injury can be demyelinated during the subsequent inflammatory response. Such demyelination can lead to decreased nerve conduction velocity and eventual death of the "denuded" axons, producing impaired sensory and motor function.

"This work demonstrates the versatility of hESCs and their potential utility for broad-based cellular therapeutics," added Thomas B. Okarma, Ph.D., M.D., Geron's president and chief executive officer. "In these studies, oligodendroglial progenitors were produced multiple times from the same human embryonic stem cell line over a period of months. The success of these studies and potential economies from large batch production of oligodendroglial progenitors from hESCs supports development of this potential product for the treatment of patients with acute spinal cord injury."

Geron is now initiating formal preclinical safety and efficacy studies and is planning for scaled-up production of the cells for potential use in human clinical trials.

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 September 30, 2003.