Chicago — Researchers are making progress but still have a long way to go in the field of bioengineered-assisted wound healing, according to some experts.
Chicago - Researchers are making progress but still have a long way to go in the field of bioengineered-assisted wound healing, according to some experts.
"We've come a long way from keratinocyte sheets, which were grown in the laboratory from one patient for autologous use," according to Vincent Falanga, M.D., president of the Wound Healing Society as well as a professor of dermatology and biochemistry at the Boston University School of Medicine, and chairman of dermatology and skin surgery at the Roger Williams Medical Center in Providence, R.I. "To be sure, that was a major breakthrough, because of the well-known difficulty in growing keratinocytes compared to other cell types," he says.
On the horizon
On the horizon, Dr. Falanga says, people are trying to manipulate stem cells.
"Some investigators are working on the use of bone marrow-derived stem cells to stimulate the healing process," he says. (See related story.)
Researchers are also experimenting with different stimulatory signals to influence the developmental pathway the cells follow. Therefore, it may not be enough to introduce and apply stem cells; other signals may be required to direct the conversion of these stem cells to the desired cell type.
Adult, embryonic differentiation
Dr. Falanga says that clinicians, including practicing dermatologists, need to realize that embryonic stem cells differ from adult stem cells because embryonic stem cells can give rise to any tissue, while adult stem cells from a specific organ or tissue are used to replenish the stem cells and their progeny within that tissue.
He notes that nobody is stopping embryonic stem cell research - as long as researchers don't use federal money to do their work. Embryonic stem cell research is permitted, but it cannot be funded with money from the federal government. He predicts that this situation will change, driven by scientific needs and political pressures.
For now, according to guidelines established by President Bush, investigators have access to a limited number of embryonic stem cells. However, in Dr. Falanga's opinion, that decision has not resulted in a logical approach to the use of embryonic stem cells. The stem cell lines that are available are few and hard to obtain. A small vial costs $5,000 or more, and there is increasing recognition that the approved embryonic stem cell lines may have been contaminated with viruses derived from mouse cells.
Dr. Falanga suggests that an intriguing question is: What would happen if, within the present guidelines, a biotechnology company developed useful therapies using embryonic stem cells? Would the FDA be allowed to approve that therapy? If not, the products may only be available outside the United States.
Dr. Falanga predicts that changes in government policy will occur, specifically with the use of discarded embryonic cells used for in vitro fertilization, as those cells are discarded anyway.
While the controversy about embryonic stem cells continues, Dr. Falanga says progress is being made in other areas.
"Clinicians continue to use and maximize the effects of epidermal substitutes," he says. "These keratinocyte sheets, both autologous and allogeneic, have been used in burns and in skin wounds."
At first, Dr. Falanga says, keratinocytes were cultured from the patient's epidermis and were grown into sheets in the laboratory to ultimately cover a denuded surface.
Dr. Falanga says a European company is making keratinocyte sheets from patients' hair follicles.