But whether and how soon stem cells are used to treat human diseases may depend less on science and more on the politics surrounding the abortion debate. Some of the cells are derived from human embryos discarded from fertility clinics. The Early Show's Dr. Emily Senay reports.
After his accident in 1995 Reeve challenged scientists to cure his paralysis before he turns 50. That's two years from now. Whether or not that happens, Reeve believes the eventual answer may lie with embryonic stem cells.
"It's called the body's self-repair kit," Reeve says. "You take these cells that are totally undifferentiated, have no identity, and you can make a new heart, a new liver. You can cure diabetes, Alzheimer's, Parkinson's, spinal cord injuries. It's an amazing resource."
Reeve's enthusiasm for the research is shared by Dr. John Gearhart, who helped discover stem cells and who says their promise lies in the near, not distant future, at least for some diseases. "With something like Parkinson's (the) types of neurons that we're talking about a three- to five-year period. I'm convinced of that," the doctor says.
Stem cells are already working in mice with spinal cord injuries. "That is, in my opinion, further proof of the basic principle that the body wants to heal itself," Reeve says.
In 1996, however, Congress banned federal funding of all research involving embryos, forcing scientists to rely solely on private funds.
Senator Sam Brownback, R.-Kansas, is leading the movement to keep the ban in place. "The embryonic stem cell comes from an embryo. An embryo is a human life that we've historically protected human life. The law protects human life," Brownback says.
"These are cells that have been going into the garbage for nearly 40 years. Now why are we suddenly freaking out about it?" Reeve argues.
Many senators agree with Reeve, including Arlen Specter, who wants the ban lifted. "No. 1, we are not dealing with human life when we're dealing with discarded embryos. No. 2, there is an opportunity to cure major diseases like Parkinson's and Alzheimer's and other maladies, and we ought to do it," Specter says.
Harvard scientist Evan Synder also agrees. With private funds, he's shown that stem cells can repair Lou Gehrig's disease and spinal cord injuries in mice. But he says research would go much faster if the government funded it.
"To have in your hands the ability to help somebody and to not take advantage of that is perhaps the greatest sin and ethical breach of all," says Synder, of Children's Hospital in Boston.
While scientists have found stem cells can also be found in the adult human body, they are harder to locate and harvest.
ince his paralyzing horseback riding accident, actor Reeve has vowed he will walk again. He endured countless hours of rehabilitation to keep his body ready for that day. A few years ago he almost lost everything when his leg became infected. He overcame the infection and now believes his goal of walking is closer than ever, because of research with human embryonic stem cells.
"This time I'm sitting. And next time I'll walk here," he declared to a cheering audience in May 1998.
"There's no single magic bullet," Reeve notes. "But I think that stem cells will lead the way if we want to get rid of these diseases. If we want to ease the suffering of millions, we now have a new tool, and we should just thank God for it."
Reeve stands by the controversial commercial that aired during the last Super Bowl that simulated him walking by using footage of another person. "The only objection I had to the commercial actually was I didn't care for the body they used. I thought, 'I hope I'm not that porky,'" Reeve quips.
Reeve has extended his target date for standing, though, by two years, to 2004.