Aug. 10, 2009 — Fat may carry negative connotations in today's world, but the stem cells found in fat tissue may prove valuable for their potential to heal wounds.
As Shayn Peirce-Cottler, an assistant professor of biomedical engineering at the University of Virginia, describes them, they are hard-working and tough. Although these adult stem cells lack the infinite plasticity of embryonic stem cells, they can be used for therapeutic purposes without raising the ethical issues that have made stem cell research so controversial. And, as Peirce-Cottler has found in the course of a series of collaborations with Dr. Adam Katz, an associate professor of plastic surgery, their healing powers are considerable.
Abundant, Tough and Therapeutic
Fat stem cells, known as adipose stromal cells, are easily separated from fat tissue after liposuction. An advantage of liposuction is that it is much less invasive than the process used for harvesting stem cells from bone marrow, the most prized source of adult stem cells. Adipose stromal cells are also more plentiful than bone marrow stem cells, and they are better able to tolerate harsh environments.
This last quality is particularly important. From a medical point of view, it means that adipose stromal cells can be applied under conditions that would destroy other cells. In preclinical studies, Katz and Peirce-Cottler have used them successfully to treat chronic diabetic ulcers, open sores characterized by low levels of oxygen and high levels of bacteria.
"In these circumstances, they produce a sufficient quantity of growth factors so that the wound-healing response is virtually normal," Peirce-Cottler said.
From an engineering perspective, the cells' hardiness is equally compelling. They can readily withstand the processes needed to deliver them to a site on or in the body. For instance, Peter Stapor, a research assistant in Peirce-Cottler's laboratory, developed an airbrush to spray the cells on wounds while he was still an undergraduate student.
Setting the Stage for Future Applications
Peirce-Cottler and Katz are currently exploring a number of other applications for adipose stromal cells to treat complications of diabetes, including critical limb ischemia, a condition that results when blood vessels in the lower limbs are blocked. The cells have been successful in promoting the formation of new blood vessels.
In addition, Peirce-Cottler and Katz, along with Dr. Paul Yates, assistant professor of ophthalmology, have applied for a grant to further investigate the use of adipose stromal cells to treat degenerative eye disease, like macular degeneration and diabetic retinopathy.
Peirce-Cottler's laboratory has been focusing on a number of technical challenges that must be overcome if the therapeutic potential of adipose stromal cells is to be realized. When stromal cells are injected into the body, most end up in the lungs, liver and spleen, organs designed to filter substances out of the body. She is investigating techniques to improve their homing ability.
She is also collaborating with James Landers, a professor with appointments in chemistry, mechanical engineering and pathology, to develop microfluidic chips that will enable her to sort out the different sub-populations of adipose stem cells and to characterize their properties.
Enlisting the Energies and Enthusiasm of Undergraduates
Undergraduates like Stapor, a 2008 biomedical engineering alumnus, have been drawn to Peirce-Cottler's and Katz's stem cell research because they can put their engineering knowledge to work to help others. Blair Stocks, who graduated in May with a degree in biomedical engineering, won a Stull Family Award from the University to create high-throughput methods of cultivating adipose stromal cells, and 2007 biomedical engineering graduates Alexis Bailey and Jennifer Saik took first place at the Engineering School's Undergraduate Research and Design Symposium for developing fluorescent techniques to track adipose stromal cells as they move through the body.
"Students jump at the chance to do this kind of research," Peirce-Cottler said, "because it's a case where engineering can make a dramatic difference in improving the lives of patients."