Harvard scientists are offering colleagues free access to 17 new human embryonic stem cell lines developed without government money, hoping to boost research that the Bush administration has tried to restrict.

“I think that the field needs to be stimulated, and this is an excellent way of stimulating the field,” said Dr. Leonard Zon, president of the International Society for Stem Cell Research and a professor of pediatrics at Harvard’s Children’s Hospital Boston.

Zon, who was not involved in the project, said the new stem cell lines not only doubled the number available to scientists, but also were more user-friendly than the 15 lines eligible for federal research dollars.

Stem cells are the body’s building blocks and have the potential to become many different types of cells. Scientists think the cells can be coaxed into specific cells to repair organs or treat diseases such as diabetes, Parkinson’s and Alzheimer’s.

Stem cells are typically taken from days-old human embryos. Then the cells are grown in a laboratory into lines or colonies.

Because the human embryos are destroyed when the stem cells are extracted, the process is highly controversial among religious conservatives. In 2001, President Bush restricted federal research funding to experiments involving only those cell lines in existence at the time.

That has led some scientists to find other ways of funding their work.

Dr. Douglas Melton’s lab at Harvard used private funding to create the new set of stem cell lines for research on diabetes and made them available Wednesday to other scientists.

Melton’s funding came from Harvard, the Juvenile Diabetes Research Foundation and the Howard Hughes Medical Institute, a medical research organization. Melton is an institute employee based at Harvard.

Some scientists complain that the 15 approved lines are expensive — as much as $5,000 each — and hard to get and to use. Melton said the 17 new lines would be freely available, though scientists cannot use federal money to work with them.

At the same time, he said, “it’s quite clear that the number we’ve now provided and the others that are in existence worldwide are insufficient for all of the studies and the demand.”

Dr. James F. Battey, head of the National Institutes of Health’s stem cell task force, said not enough was known about the 15 cell lines to know if they would be sufficient. He said the NIH had given an estimated $28 million in the past two years for embryonic stem cell research.

“This is a pretty new area of science, and what’s unknown is far greater than what’s known about these cells,” Battey said.

The development of the new stem cell lines was widely reported last fall when Melton discussed them at a conference. A report on the work will appear in the March 25 issue of the New England Journal of Medicine, whose editors called on the government to fund the new cell lines.

Melton and his colleagues derived the new colonies from 344 excess frozen embryos from a fertility clinic, Boston IVF, with the consent of the owners. The researchers will use the new lines to continue their work on type 1 diabetes and try to make insulin-producing pancreatic cells.