Boston-area medical experts called for more uniform federal stem cell research policies, and said having inconsistent policies leads to less collaboration among scientists and misconceptions that give the public a negative view of the field.

Harvard Medical Center pediatric instructor William Lensch, who is affiliated with the Stem Cell Institute, said public policy has had “chilling effects” on stem cell research, making it impractical for universities and research institutions to study it, during a panel discussion at the Boston Bar Association.

“Policy has been tough on research,” Lensch said. “We can’t even determine how much damage has been done, because nothing has even happened yet.”

“There tends to be duplicated effort between institutions,” Lensch said. He said institutions tend to collaborate on research, and said if other states followed the example of California, a leader in stem cell funding and standards, they could better work together.

He addressed stem cell research opponents who say the work destroys life, but said most cell populations are created in vitro — in a Petri dish — and not taken from a fetus. “Inaccurate” ideas, like calling the process cloning, generates hysteria, Lensch said.

Children’s Hospital Boston deputy general counsel Patrick Taylor said self-regulation like International Society for Stem Cell Research’s international ethics standards, should be used as a guideline for policy-making.

“A human research regulation structure just doesn’t exist yet,” he said. “It is being hand-built.”

In 2001, President George W. Bush signed an executive order restricting federal funds to research on existing embryonic stem cells and making it illegal to use federal funds to destroy an embryo for stem cell research.

Taylor said strict limits on federal funding force states to create their own policies based on individual ethical decisions and available funds. Institutions cannot accept research done out-of-state if states’ policies do not have similar research standards, he said.

Scientists’ limited access to resources has led some institutions to consider commercial research, Taylor said. The problem with commercial research is that the data is not as widely shared because of commercial licenses, he said.

Taylor said the University of Massachusetts should get more analysis data from other research institutes. Last week the State Senate approved Gov. Deval Patrick’s $1 billion Life Sciences Bill, approved by the House earlier this year.