Stem Cells and Tissue Engineering Offer Treatment Breakthroughs

NEW YORK CITY, March 13 - The use of stem cells for treating human diseases and growing new organ tissue will likely be a reality in our lifetime, researchers said this week at a two-day symposium at The New York Academy of Medicine.

"I think we will be in (human) clinical trials in three to five years with some of these cell lines," said John Gearhart, Ph.D., a pioneering stem cell researcher and professor at the Johns Hopkins School of Medicine in Baltimore.

Stem cell treatment for Parkinson's, a degenerative disease of the nervous system, is a promising candidate for human clinical trials, Gearhart told more than 100 people at the Cell & Tissue Engineering conference. Restoring some nerve function in patients with spinal cord injury and Multiple Sclerosis (M.S.) is another "achievable goal" for the foreseeable future, said Dr. John McDonald III, director of the Spinal Cord Injury Program at the Washington University School of Medicine in St. Louis.

Such treatment "won't get a person up and walking," McDonald said. But it could improve a patient's control over bowels and bladder, hand use and other body functions.

"We don't need to cure neurologic injuries. We just need to partially repair them," said McDonald, who was among 19 speakers at the event. "These are doable goals."

Stem cells are like blank canvases that can develop into most human cell types. In the case of people with M.S., for example, stem cells could theoretically be engineered to rebuild important tissue called "myelin." This tissue, which is destroyed in M.S. patients, insulates nerves and allows impulse conduction in the body. In lab experiments, stem cells were implanted in the spinal cords of paralyzed rats. Myelin regrowth occurred and the rats regained movement following this procedure - an exciting correlation, McDonald said.

The conference, one in a series of Basic Science Symposiums organized by the Academy, provided a forum to learn about the breadth of stem cell therapy and tissue engineering research worldwide.

Jennifer West, an associate professor in the Rice University Department of Bioengineering in Houston, explained her attempts to develop the ideal "scaffolding materials" on which to grow human tissue. Scaffolds must accomplish various tasks, including providing support for tissue as it grows, and blocking unwanted cells from adhering. Each scaffold must be built from carefully chosen material that the body does not reject.

The fields of stem cell therapy and tissue growth have been naturally converging in attempts to grow full-blown human organs. Until the complicated engineering process is perfected, organs will probably be used less for their whole than for their parts - for example, to patch-up an aging heart -- said Michael Sefton, Director of the Institute of Biomaterials & Biomedical Engineering at the University of Toronto. But an engineered organ must still be proven capable of critical tasks like growing blood vessels that work.

"A critical question here is, are the blood vessels functional? We really aren't at that point yet," Sefton said. "A heart has to pump blood."

Discussions of replacement organs and stem cell therapy naturally evoke fears that the technology could be misused. In a Monday luncheon address at the conference, Harold T. Shapiro, who chaired President Clinton's National Bioethics Advisory Commission, pleaded with scientists to respect the opinion of stem-cell research opponents. The rapid pace of scientific advancements in this arena is making some camps uncomfortable, he said.

"They may be wrong, they may be ill-advised, but it's not out of ignorance," said Shapiro, past president of Princeton University. "It's not easy to know what to do. We should expect that we're going to have a constant struggle."

Researchers' use of embryonic stem cells - which are harvested by destroying an embryo - has intensified the perpetual debate over whether an embryo should enjoy the moral status of a person. Opponents say it should, and maintain that stem-cell research constitutes the taking of a human life. Scientists tend to vigorously support the research because of its potential for improving medical treatments.

There has been a long tradition of societal struggle over benefits and drawbacks of progress, Shapiro pointed out. In Greek mythology, the ship "Argo" was acclaimed by some because it could sail great distances, but derided by others because trees were felled to build it.

"You're going to be making decisions in many morally contested areas," Shapiro said. "The more rapidly science progresses, the more ethical issues that come up."

Shapiro explained that the government can be expected to alter its view on research funding every few years, or whenever administrations change. President Clinton had approved federal funding for research involving leftover embryonic stem cells from fertility clinics, for example. But President Bush announced a more restrictive policy last year, allowing funding for research using an existing 70 or so stem cell lines.

Stem cells retrieved from embryos are not the only option in this new research realm, of course. Adult stem cells hold greater potential than has been widely acknowledged, said Dr. Catherine Verfaillie, Director of the Stem Cell Institute at the University of Minnesota. A growing number of studies in the past 4-5 years have shown that adult stem cells can grow into a variety of tissue types, including skeletal muscle, cardiac muscle, and endothelium, a layer of cells that line cavities of the heart, blood, and lymph vessels. This is very significant, since an oft-mentioned drawback of adult stem cells is that they're less capable of so-called "differentiation" than embryonic stem cells.

In her research, Verfaillie stumbled across a previously unfamiliar type of adult stem cell, which she named "MAPC." She describes the cells as having similar characteristics of embryonic stem cells. Verfaillie reported that she has successfully coaxed a single MAPC to grow into several different cell types in a rodent, including both endothelium and liver-like cells.

"There's obviously an enormous amount of excitement, however, an enormous amount of questions that are still unclear," Verfaillie said.

Posted on March 13, 2002

 Print   Subscribe

Contact:
Andrew J. Martin
Director of Communications
The New York Academy of Medicine
1216 Fifth Avenue
New York, New York 10029
212-822-7285
amartin@nyam.org

Press Release Archive