California-based Geron was once feared for its patent might. Because the company held exclusive rights to many embryonic stem cells developed at the University of Wisconsin, biotechnology rivals believed the company would establish a stem cell monopoly. In 1999 Geron purchased rights to the cloning technology used to make Dolly the sheep in Scotland, a technique given patent protection by the British government a year later.

The controversy over Geron's extensive patent holdings only subsided in 2002 when the company and the University of Wisconsin reached an agreement that limited Geron's patent rights and promised to allow other scientists access to the stem cell lines.

Today the company is still operating at a loss--$9.7m (£5.2m) in the first three months of 2005--and fears of its domination of the stem cell market have evaporated. Yet Geron is still an important force in this area of research and is expected to be one of the main beneficiaries of a new California fund for stem cell research.

Geron, founded in 1992, was one of the first public companies to study embryonic stem cells. In the late 1990s its attention turned to telomerase, a compound the group identified through its study of stem cells as key to the aging process. Cell levels of telomerase decline as humans age. Geron scientists hope that by boosting amounts of the compound in the body, they can battle diseases such as AIDS and cancer. In March the company founded TA Therapeutics, a joint venture with a Hong Kong University research institute, to explore telomerase applications.

But Geron's interest in embryonic stem cells as a therapy in their own right has been renewed. The company is pursuing research in a wide number of disease areas, including Parkinson's, heart disease, diabetes, arthritis, blood disease, osteoporosis and organ transplantation. While none of the therapies has been tested in humans yet, Geron says it may soon initiate clinical trials in spinal cord injury.

In March the company published research explaining how human embryonic stem cells could be grown without the help of "feeder cells". Feeders such as mouse cells were used to propagate early stem cell populations. Geron had posted research on how to grow the cleaner embryonic stem cells on its Web site in September of 2002, but until this year's publication in the journal Stem Cells, many had doubted the technology really worked.