$3b Calif. stem-cell plan may hurt Mass.

California's new $3 billion initiative to fund stem-cell research could sharply alter the landscape of a cutting-edge field in which Massachusetts has achieved national prominence, several scientists said yesterday.

Proposition 71, backed by Republican Govenor Arnold Schwarzenegger along with a coalition of patient advocates, celebrities and venture capitalists, will establish an independent California Institute for Regenerative Medicine authorized to disburse some $300 million annually over the next decade. That amount -- substantially more than the entire federal budget for stem-cell research -- will go only to labs or companies located in California.

The money will be targeted at research the federal government does not fund, most prominently the highly charged field of human embryonic stem cells, and also the creation of cloned human embryos for disease research. On Aug. 9, 2001, President Bush said the federal government would not pay for research on human embryonic stem cells created after that date.

On a national level, an influx of money on that scale could boost American science in an important area where other countries have been moving to establish a beachhead. The availablity of research money would also encourage more young scientists to enter the field, despite the political controversy that surrounds it.

But it has also triggered worries about the impact on Massachusetts and other states that have staked a claim to prominence in stem-cell research. Though stem cells have limited commercial application now, some local scientists said they feared a potential repeat of the story of the personal computer -- where California's Silicon Valley overtook the state's early lead and ran away with the revolution.

''I would really hate to see that happen again," said Dr. David T. Scadden, a stem cell scientist at Massachusetts General Hospital who is codirector of the recently launched Harvard Stem Cell Institute. ''But they have an opportunity to create programs there that will be difficult to match."

Massachusetts is home to some of the world's foremost stem-cell researchers, chiefly at Harvard, MIT, and other universities. In Worcester, the biotech firm Advanced Cell Technology Inc., has also been active in the field.

Local stem-cell scientists interviewed yesterday said that even before Election Day they had already begun to receive enticing offers to move to California, and expect the recruiting to become only more intense.

Robert Lanza, the medical director of ACT, said that in the last few weeks he has been approached by three different investors who wanted his help to set up new stem-cell ventures in California.

''I want to stay in Massachusetts, and tried to convince them they should set up their companies here," said Lanza. ''It's a depressing fact that they said no."

In part because of the money, ACT is planning to open a facility in California, Lanza said, but hopes to keep its Massachusetts lab as well.

The passage of the California proposition adds to the gathering battle between the federal government and the states -- and, increasingly, among the states themselves -- over the future of stem-cell research. New Jersey started a stem-cell initiative this year using $6.5 million in initial public money. Harvard University launched a stem-cell institute in April, with a fund-raising goal of around $100 million, which will include research not supported by the federal government.

But the California measure dwarfs the others, and top stem-cell scientists in California have been relishing the prospects. Dr. Irving Weissman, a leading stem-cell researcher at Stanford, said yesterday he is already working on plans to build new facilities and hopes to lure colleagues from Boston and elsewhere to join him.

The new California institute will set up a panel of scientists to review grant applications, who will then forward their recommendations to an oversight committee appointed by several state officials. The measure directs the committee to choose applications that would not otherwise be funded by the federal government. The work will be financed by state bonds -- no more than $350 million in any given year and no more than $3 billion total -- though the committee is not required to borrow the full amount.

The bonds will be repaid by the taxpayers, beginning in five years, but the measure envisions that some of the costs will be repaid by royalties from patents on new discoveries.

Biologists are eager to explore the regenerative potential of stem cells because the cells have the ability to replenish themselves and also create the more specialized cells that make up the body. Of particular interest are human embryonic stem cells, which, unlike adult stem cells, have the ability to mature into any of the body's tissues. Scientists typically get new batches of human embryonic stem cells from human embryos created for fertility treatments that couples plan to destroy.

The California measure was inspired by frustration with the Bush funding policy, especially among advocacy groups for diseases that might be helped by embryonic stem-cell research. Last year the federal government spent about $25 million on embryonic stem-cell research.

The Massachusetts Senate has twice passed a measure that declares the state's support for the research, though no public funds. The measure was dropped both times in negotiations with the House. A spokesman for Senate President Robert E. Travaglini, who fought for the measure, said they remain concerned about the state's competitive position, but have not yet decided how they want to address the issue in the next session of the Legislature.

Stanford's Weissman said he hopes that Massachusetts and other states follow the lead of California, even if it might make it harder for him to recruit top talents.

''But it might take Massachusetts and New York losing a couple of key scientists for the legislatures to understand," he said.

Gareth Cook can be reached at cook@globe.com.