WASHINGTON, June 28 (UPI) -- Experts said Wednesday scientists are making progress in the potential to use both embryonic and adult stem cells to treat heart disease, and clinical applications are expected soon.
Deepak Srivastava, director of the University of California at San Francisco's Gladstone institute of cardiovascular disease, told United Press International embryonic stem cells hold the greatest promise for regenerating heart tissue and could be in the clinic in the next several years.
"There's a lot more that needs to be done in animal trials first before considering clinical trials ... but maybe within the next five years is a reasonable goal," said Srivastava, who co-authored an article that appears in the June 29 issue of Nature.
He said embryonic stem cells hold "a lot of promise" for being used to treat heart disease and scientists have made great strides in understanding how to direct the cells to become heart cells. The next challenge is ensuring they integrate properly with the existing heart cells once they are transplanted into the body, he said.
"The problem with the adult stem cells is that they're very limited in number and their capacity to regenerate significant portions of tissue," he said.
It's conceivable adult stem cells could eventually prove beneficial for replacing heart tissue "but the route to that is not as clear, whereas the route to taking embryonic stem cells and encouraging them to become heart cells, that path is pretty clear," he said.
Robert Lanza, vice president of medical and scientific affairs at Advanced Cell Technology in Worcester, Mass., said his company plans to get embryonic stem cell-derived therapies for heart disease in the clinic even earlier.
"Optimistically, we plan to file an IND in 2008 for hemangioblasts derived from human embryonic stem cells," Lanza told UPI. "One of the lead applications would be cardiovascular disease," he added.
Lanza said his company's first IND for a therapy derived from embryonic stem cell therapy could be filed late next year, but that would be for macular degeneration.
His company plans to arrange a meeting with the Food and Drug Administration about their intended INDs "very soon," he said.
Lanza said work with adult and embryonic stem cells should be pursued because both could prove valuable, but ultimately embryonic cells would probably turn out to be superior for regenerating heart tissue.
"In the coming years, I think we'll see adult stem cells superceded by new cells created in the lab from embryonic stem cells," he said. This could consist of stem cells turned into cardiomyocytes or early progenitor cells that can injected into the body and will go to the site of vascular injury.
"It's like the Model T or the Ferrari," he said, with adult stem cells being the Model T. "I think we can do better."
As the field progresses, advocates expect the moral debate over the research to diminish, which could have important ramifications for expanded funding.
"If embryonic stem cell research is really allowed to show its promise, then the political controversy will fade away," Sean Tipton, president of the Coalition for the Advancement of Medical Research, an association of patient groups and medical organizations that support embryonic stem cell research, told UPI.
"The rhetoric of the opponents is a catch-22," Tipton added. "They say, 'You can't prove this stuff is going to work and therefore we're going to ban the research that's going to allow you to prove it will work.'"
President Bush, who opposes embryonic stem cell research because it requires the destruction of an embryo, has limited federal funding to several dozen approved stem cell lines, which critics argue has hampered progress.
The House has passed a bill -- the Stem Cell Research Enhancement Act -- that would relax the restrictions and allow federal funding to go towards surplus embryos from fertilization clinics that are destined to be destroyed. The Senate has not yet voted on the bill but majority leader Sen. Bill Frist, R-Tenn., has pledged to bring it to the floor for a vote this summer.
Frist has not kept similar promises in the past, but he may follow through this time around due to the political climate and his presidential aspirations. In addition, scientists appear to have developed a technique that allows for obtaining the stem cells without destroying the embryo, which could satisfy those who object to the research on moral grounds.
Lanza has published previous research on the technique in mice and he says further research that is pending publication has shown it works with human cells.
Bush has said he will veto the bill if the Senate passes it. If so, it would be his first veto.