Regenerative Medicine

Does regenerative medicine hold the keys to rebuilding damaged organs, tissue and muscle? Atlanta Medicine recently spoke with some Atlanta area researchers about the promise regenerative medicine holds for the future of medicine.

According to Arshed A. Quyyumi, M.D., a professor of medicine in Emory University School of Medicine’s Division of Cardiology, stem cell therapy may offer hope to people with cardiovascular disease in two ways: by treating people with heart disease and by providing evidence to researchers that may help them learn more about the body’s regenerative capacity. He says that progenitor cells, the early descendants of stem cells that have the ability to form different types of tissues and organs, may yield the most valuable information in the study of stem cell therapy as treat-ment for heart disease.

“The number of progenitor cells in a person’s body are reflective of their ability to heal and regenerate. They reflect the health of the reparative system in our bodies,” he says. “We have learned that people with low numbers of progenitor cells are less likely to heal, regenerate and repair. For people with heart disease, this means that they are more likely to succumb to their condition if their level of progenitor cells is low.”

Quyyumi adds that comparable studies conducted around the world have provided similar results.

“It’s not a small observation,” he says. “These studies of progenitor cells have all produced the same result in terms of predictive capacity.”

As for the treatment aspect, Quyyumi says that stem cell therapy offers promise for people with irreparable heart damage. Various stem cells, which are injected into the patient, are harvested either from the patient’s own bone marrow or from a do-nor.

“People who are participating in this research are those who have advanced disease, blockages or heart failure, for whom the usual treatment options have either been exhausted, haven’t worked or can’t be performed,” he says.

So far, results have been encouraging.

“Some clinical trials show that stem cell therapy has improved heart function in pa-tients and that they are living longer,” says Quyyumi. “Ultimately, we hope that stem cell therapy, in some form, will be available as a choice of treatment down the line for people with advanced heart disease and that we can salvage these kinds of conditions.”

Public Bank of Renewable Stem Cells Offers Promise

Recent clinical evidence shows that stem cell therapy is on the cusp of working very effectively across a broad range of applications, says Todd McAllister, Ph.D., executive director of the Amnion Foundation. McAllister and his colleagues, including Nicolas A. Chronos, M.D., managing partner of Cardiology Care Clinics, are collaboratively researching the value of amnion stem cells, found in the placenta and the am-niotic fluid surrounding a fetus, in the development of regenerative medicine treat-ments and technologies.

“The reality is that current stem cell therapies aren’t performing up to the high ex-pectations we had. Stem cells have been so hyped that now there is an expectation that we can inject stem cells after a heart attack, for example, and have the patient run a marathon the next day. We aren’t there yet,” McAllister says. “Most clinical studies use one of two basic approaches for stem cell therapy – harvesting cells from the patient’s own fat or bone marrow [autologous] or using cells from a master do-nor [allogenic].”

Both models have potential limitations, he adds. “The autologous model often uses cells taken from older, sicker patients, which may lack the regenerative capacity to cure the patient. The allogeneic model has the advantage of providing younger, healthier cells off the shelf, but immune or inflammatory responses to these cells may limit their long-term survival in the recipient.”

Dr. McAllister says that the Amnion Foundation is seeking to bridge the gap between the two models by building a bank of thousands of donors of powerful young stem cells, from which there will be perfect immunological matches for every person who needs them.

“Our objective is to extend upon the successes that have been documented with cord blood banking for blood cancers, in which the cells injected have a greater survival rate without a graft vs. host response,” McAllister explains. “While this seems an ob-vious extension, this public banking model is novel for treatments beyond diseases of the blood.”

Chronos says that the way stem cells work is not totally clear.

“We aren’t sure if stem cells work because they engraft into damaged tissues and then can turn into functional cells, or if they simply produce growth factors or other repair signals at the site of damage,” he says. “What we do know is that, as we age, there may be a reduced number of stem cells in our bodies, and they may not work as well once disease has formed.”

Forming a bank of amnion stems cells, available to the public, makes a tremendous amount of sense, says Chronos.

“One of the beauties of harvesting amnion stem cells is that they don’t pose an ethical dilemma to harvest. They are literally being thrown away after a baby is born,” he says. “These amnion cells are also incredibly multipotent, meaning that they can develop into almost any cell type. While we tend to think that all stem cells have this power, most have relatively narrow pathways that they can differentiate down.

“Amnion cells may be so young in their lineage that they can actually be driven, in the right environment, to rebuild any organ you want to treat,” he says.

“This characteristic, coupled with immunological matching in the public banking model, may finally help realize the full potential of stem cell therapies.” For more information about Amnion Foundation, visit www.amnionfoundation.org.