by Deena Beasley

Last Updated: 2008-07-08 13:00:43 -0400 (Reuters Health)

WASHINGTON (Reuters) – Pfizer Inc, the world’s largest drug maker, is moving, with little fanfare, to develop stem cell therapies, starting with drugs that modify the body’s regenerative processes.

"The science is promising enough to put our resources behind it," said Ruth McKernan, head of Pfizer Regenerative Medicine. The unit, quietly created in April, is located in the United Kingdom and Cambridge, Massachusetts.

Few pharmaceutical companies have made big investments in stem cell research amid the ethical controversy surrounding destruction of human embryos and the hard truth that medical therapies are still many years, if not decades, away.

Stem cells are the body’s master cells, giving rise to tissues, organs and blood. Scientists hope to harness their power to create a new field of regenerative medicine, offering cures for diseases of the brain, cancer and serious injuries.

Pfizer and other drug makers have for many years been using stem cells as part of the drug discovery process — using them to test for toxicity, for instance.

McKernan said Pfizer is well placed to expand its expertise in developing so-called small molecule drugs, a term commonly used to refer to oral pills, to include drugs that target stem cells.

"In neuroscience, amplifying the birth of new neurons is a promising area," she explained.

Pfizer’s initial tactic of pairing small molecule drugs with stem cell biology is something of a step back from more aggressive use of stem cells as direct therapies for disease.

"This is way different from injecting cells into the heads of people who have had a stroke," McKernan said. "On the other hand, we don’t know whether small molecules will be able to produce the breadth of effect that cells do."

She believes using small molecule drugs to target stem cells will avoid some of the regulatory and logistical issues that have stymied stem cell researchers.

Geron Corp, for instance, is still in discussions with U.S. Food and Drug Administration after the agency in May placed a clinical hold on the company’s test of a stem cell therapy for spinal cord injury. The trial would be the first U.S. study of a stem cell treatment in humans.

The use of stem cells as actual therapies also requires the manufacture of the cells — a process fraught with complication and ethical concerns.

Shortly after U.S. President George Bush took office in 2001, he limited federal funding to research involving existing stem cell lines, citing concerns about the morality of destroying human embryos to extract the versatile cells.

Pfizer’s international operations and funding of its own research nullify the impact of the U.S. policy on the company, which says it operates under stem cell research guidelines set by the U.S. National Academy of Sciences and equivalent organizations around the world.

Meanwhile, the issue of embryonic stem cells in general is becoming less of a focus for the field, McKernan said.

That is due to advances in transforming ordinary human cells into cells that looks and act like embryonic stem cells — known as induced pluripotent stem cells, or iPS for short.

"The technology is certainly being used successfully," McKernan said.

She said many smaller biotech companies are investing in the space.

"Some will flourish and grow and some will consolidate," McKernan said. "Lots of people want to talk with us, collaborate with us. I’m seeing a real appetite for partnerships."

(Editing by Derek Caney)

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