Fat: A source for stem cells?

Cosmetic Surgery Times
Taken from the November/December 2004 Issue

Written by Cheryl Guttman
Staff Correspondent

St. Louis - Ongoing research points to the enormous potential for using lipo-derived stem cells in regenerative medicine applications to restore form and function, said Kacey Marra, Ph.D., at the World Congress of Liposuction Surgery meeting.

Dr. Marra, assistant professor, departments of surgery and bioengineering, University of Pittsburgh, described for the attendees the advantages of adipose tissue as a source of stem cells and reviewed the findings from research being conducted in her own laboratory and by other investigators around the world to characterize the biology of adipose tissue-derived stem cells (ADSCs) and their potential in tissue engineering applications.

Collaboration encouraged

"Surgeons performing procedures involving removal of adipose tissue should realize adult stem cells derived from otherwise discarded fat might be used in numerous possible applications in tissue engineering," Dr. Marra says. "Since the speed at which progress will be made in this area relates to the number of involved researchers, we urge surgeons to begin collaborating with biomedical engineers and other scientists at their institutions in order to bring new therapies more quickly into the clinical arena."

Fat's advantages

While fat is just one tissue source for autologous stem cells, its advantages are that it is easily obtainable and a plentiful source of stem cells that can be easily isolated, expanded and differentiated into adipocytes, osteoblasts, chondrocytes and myocytes. "Within 24 hours, we are able to isolate 200 million stem cells from each pound of fat, and those cells can be readily expanded tenfold in culture. In contrast, bone marrow, which is more difficult to harvest, yields proportionally many fewer stem cells that are also more difficult to culture," Dr. Marra says.

Dr. Marra is also director of the Plastic Surgery Research Laboratory where she contributes her expertise in polymer science and collaborates on a number of tissue engineering projects with a multidisciplinary team that included biomedical engineers and plastic surgeons J. Peter Rubin, M.D., and Joseph Losee, M.D. Their work with ADSCs focuses particularly on applications for soft tissue and bone regeneration.

So far, researchers have been successful in differentiating animal and human ADSCs into osteoblasts and they are now working on a rabbit model to engineer a three-dimensional implant containing the osteoblasts that will be placed into skeletal defects.

Currently, they are isolating stem cells from fat harvested from male animals, differentiating the stem cells into osteoblasts, seeing the osteoblasts onto a biodegradable scaffold and trying to determine what may be the optimum time postseeding for implantation into female animals. Actual implantation into experimentally created skull defects is expected to begin at the end of this year.

"It is not possible to simply inject the osteoblasts into a defect and expect that they would take on the desired shape," Dr. Marra tells Cosmetic Surgery Times . "Therefore, we have to find a biodegradable material that will provide the proper microenvironment for the cells to adhere to and proliferate in and create a scaffold from the material into the desired shape. We will then implant it with the expectation that the framework will dissolve in vivo leaving only bone cells."

Meanwhile, she and her colleagues are also collecting adipose tissue specimens from patients undergoing liposuction, abdominoplasty, and full-body contour procedures. The doctors are studying them to characterize their stem cell yield and how well those cells can be expanded and differentiated into other types of cells. Correlations between those stem cell features and their source characteristics - i.e., patient age, gender and site of harvesting - will be analyzed in hopes of gaining valuable information to guide therapeutic decisions.

More samples needed

So far, adequate numbers of samples have not been obtained to show statistically significantly relationships. However, some trends have been noted. For example, there appears to be a decrease in stem cell yield per gram of fat with increasing donor age. "When lipo-derived stem cell tissue regeneration becomes a clinically viable therapy, we want to know what fat provides the best sources for use in difference applications, " Dr. Marra says.

Reprinted with permission from the Cosmetic Surgery Times.