It has been likened to an overfed starfish. In reality, however, what may look like just a yellow plastic thing is actually a bioreactor—a 3-dimensional breeding ground for cells—which much improves upon the 2-dimensional petri dish. Applications for bioreactors include growing pancreas, liver, bone marrow, neuronal, skin, and cancer stem cells for research and therapeutic purposes. The combination of the bioreactor to grow cells, a unique cell spraying system, and a “wound cap” offer potentially new therapies for burn victims.
The Bioreactor Group, led by McGowan Institute faculty member Joerg Gerlach, MD, PhD, Professor in the Department of Surgery, University of Pittsburgh, currently collaborates with national and international scientists with this novel research tool.
As noted, regenerating skin cells is but one of the many applications associated with a bioreactor. Dr. Gerlach’s bioreactor technology serves as part of an alternative approach to mend skin damaged by burns and abrasion-type injuries. Recent press (Newsweek and Popular Science) has highlighted Dr. Gerlach’s “skin gun”—one part of his 3-phase skin burn disease therapy. Also, in early 2008, both the Pittsburgh Tissue Engineering Initiative and the U. S. Department of Defense funded Dr. Gerlach’s efforts to further this burn repair application.
Dr. Gerlach’s skin burn disease therapy combines his bioreactor technologies with a cell spraying device—skin gun—that he and his colleagues have developed to mend burned skin. The expected protocol when a patient arrives at a hospital missing a sizable portion of skin would be as follows: Surgeons take a sample from a healthy piece of skin and isolate skin cells, including skin stem cells, using a method Gerlach and his colleagues developed.
Then the skin gun comes into play. A surgeon loads the stem cells into a sterile syringe, loads the syringe into the nozzle like a cartridge, and sprays the cells through the nozzle directly onto the wound.
"What we're doing is taking the cells, isolating them, and, in the same procedure on the same day, we're putting the cells onto the wound," Dr. Gerlach says. "The progenitor cells can act immediately. The most critical cells are present, and we are using those cells right away from the patient. We just need to take care that we are distributing the cells nicely over the wound." Hence, the spray nozzle.
Lastly, the other essential part of the Gerlach process is an innovative wound dressing. Enmeshed in what looks like a traditional dressing are tubes that are part of another bioreactor. Tubes extend from each end of the dressing—one does the work of an artery, the other a vein. When connected to an “artificial vascular system” the bioreactor bandage distributes glucose, sugar, amino acids, antibiotics, and electrolytes to the treated area. It cleans the wound, provides nutrition, and better supports the precious stem cells in the wound until they start to grow and regenerate new skin for the patient.
Dr. Gerlach reports that the procedure has been performed successfully at the Berlin Burn Center where patients have regrown skin over a burned ear or an entire face in a matter of days. This new method of regrowing skin improves on the current method: Doctors harvest skin cells and send them to an external lab where they are grown in approximately 1-3 weeks into a sheet of new skin. The new sheet of skin is then sent back to the hospital to be attached to the wound where blisters caused by secretions under the attached skin can push the sheet up and damage it. In contrast, by spraying single cells and allowing them to enter the wound to reproduce right then and there, outcomes for patients should be greatly improved.
Illustration: McGowan Institute for Regenerative Medicine.
Popular Science (06/24/08)
Regenerative Medicine Today Podcast, Dr. Joerg Gerlach (06/06/08)
The Bioreactor Group, McGowan Institute for Regenerative Medicine
Sowing the Seeds: Spraying Cells to Regrow Skin (07/2007)
PittMED (Spring 2007)