StemCells, Inc. (NASDAQ:STEM) today announced that it has received approval from the U.S. Food and Drug Administration (FDA) to initiate a clinical trial of the Company's proprietary HuCNS-SC product candidate (purified human neural stem cells) to treat Pelizaeus-Merzbacher Disease (PMD), a fatal brain disorder that mainly affects young children. This Phase I trial is designed to evaluate the safety and preliminary efficacy of HuCNS-SC cells as a treatment for PMD. Currently, there are no approved treatments for this disease.

This is the Company's second FDA-approved clinical trial to evaluate HuCNS-SC cells as a potential treatment for neurodegenerative diseases. The first such study was the Company's Phase I clinical trial of HuCNS-SC cells to treat neuronal ceroid lipofuscinoses (NCL), or Batten disease. The Phase I NCL trial will be completed in January 2009.

Patients with PMD are born with a gene mutation that results in insufficient myelination of nerve fibers in the brain, neurological impairment and eventually death. Myelin, which is produced by special cells called oligodendrocytes, insulates nerve fibers to allow electrical signals to be conducted normally. Other, more common, myelination diseases include cerebral palsy, transverse myelitis and multiple sclerosis.

Preclinical studies performed by the Company and its collaborators provide a rationale for potential therapeutic use of HuCNS-SC cells in myelination diseases. The Company has demonstrated that, when transplanted into an animal model of hypomyelination (shiverer mouse), HuCNS-SC cells engraft and differentiate into mature oligodendrocytes and form myelin sheaths around host nerve fibers. The initial myelination data in the shiverer mouse was published in the Proceedings of the National Academy of Science (Cummings, et al. 2005) and the results of additional myelination studies were presented by Nobuko Uchida, Ph.D., the Company's Vice President of Stem Cell Biology, at the International Society of Stem Cell Research annual meeting in Philadelphia earlier this year.

"PMD is one of the most severe myelin disorders known to man. Children afflicted with this disease suffer progressive neurodegeneration and an untimely death. Unfortunately, they have no option for restorative treatment," said Stephen Huhn MD, FACS, FAAP, Vice President and Head of the CNS Program at StemCells, Inc. "We are very pleased to be the first company to initiate a neural stem cell trial for a myelination disease. Establishing safety and efficacy of our cells in patients with PMD may pave the way for similar studies in patients with other myelin diseases." The Company has begun the process of seeking approval by the Investigational Review Board (IRB) of potential clinical trial sites in order to begin enrolling patients.

About Pelizaeus-Merzbacher Disease (PMD)

PMD is a rare, degenerative, central nervous system disorder and is one of a group of genetic disorders known as leukodystrophies. Leukodystrophies involve abnormal growth of the myelin sheath which is the fatty substance - or insulator - on nerve fibers in the brain and spinal cord. PMD is most commonly caused by a genetic mutation that affects an important protein found in myelin, proteolipid protein (PLP). PMD is most frequently diagnosed in early childhood and is associated with abnormal eye movements (nystagmus), abnormal muscle function, and in some cases seizures. The disease form in early infancy is referred to as connatal PMD and diagnosis in later childhood is most typically associated with the classic form. The neurological course of both forms is marked by progressive deterioration resulting in premature death.

About HuCNS-SC® Cells

StemCells' lead product candidate, HuCNS-SC cells, is a purified composition of normal human neural stem cells that are expanded and stored as banks of cells. The Company's preclinical research has shown that HuCNS-SC cells can be directly transplanted; they engraft, migrate, differentiate into neurons and glial cells; and they survive for as long as one year with no sign of tumor formation or adverse effects. These findings show that HuCNS-SC cells, when transplanted, act like normal stem cells, suggesting the possibility of a continual replenishment of normal human neural cells.

About StemCells, Inc.

StemCells, Inc. is a clinical-stage biotechnology company focused on the discovery, development and commercialization of cell-based therapeutics to treat diseases of the central nervous system and liver. The Company's product development programs seek to repair or repopulate CNS and liver tissue that has been damaged or lost as a result of disease or injury. StemCells has pioneered the discovery and development of HuCNS-SC cells, its highly purified, expandable population of human neural stem cells. StemCells owns or has exclusive rights to more than 50 issued or allowed U.S. patents and more than 150 granted or allowed non-U.S. patents. Further information about the Company is available on its web site at: www.stemcellsinc.com

Apart from statements of historical fact, the text of this press release constitutes forward-looking statements regarding, among other things, the future business operations of StemCells, Inc. (the "Company") and its ability to conduct clinical trials as well as its research and product development efforts. These forward-looking statements speak only as of the date of this news release. The Company does not undertake to update any of these forward-looking statements to reflect events or circumstances that occur after the date hereof. Such statements reflect management's current views and are based on certain assumptions that may or may not ultimately prove valid. The Company's actual results may vary materially from those contemplated in such forward-looking statements due to risks and uncertainties to which the Company is subject, including uncertainty as to whether the FDA or other applicable regulatory agencies will permit the Company to continue clinical testing in NCL, PMD or in future clinical trials of proposed therapies for other diseases or conditions despite the novel and unproven nature of the Company's technologies; uncertainties about whether the Company will receive the necessary support of a clinical study center and its ethics board to initiate a clinical trial in PMD; uncertainties regarding the Company's ability to obtain the increased capital resources needed to continue its current research and development operations and to conduct the research, preclinical development and clinical trials necessary for regulatory approvals; uncertainty as to whether HuCNS-SC and any products that may be generated in the future in the Company's cell-based programs will prove safe and clinically effective and not cause tumors or other adverse side effects; uncertainties regarding the Company's manufacturing capabilities given its increasing preclinical and clinical commitments; and other factors that are described under the heading "Risk Factors" in Item 1A of Part II of the Company's Quarterly Report on Form 10-Q.