Skin grafting tools
For skin grafting, the CelluTome Epidermal Harvesting System (Kinetic Concepts Inc./Acelity), commercially available in the United States and Europe, allows harvesting of epidermal grafts without creating donor-site scars. "You place this little device, without anesthesia, on the donor site (typically the inner thigh) for 20 to 45 minutes." Using suction, the device raises approximately 30 tiny microdomes of epidermis. Pressing a lever shears all the grafts off, so they can be placed on a wound-dressing sheet. "Then you transfer those little pieces of epidermis onto the wound. When you put them in culture on patients' skin, the keratinocytes migrate out of the microdomes" to speed wound healing.6
Specifically, said Dr. Kirsner, the micrografts deliver growth factors to the wound, resulting in edge advancement. Confocal microscopy moreover has shown that the grafts indeed "take" where they're planted, resulting in dots of new epidermis across the wound surface, he said. Because the process also transfers melanocytes, it works for vitiligo as well. At the donor site, "You can't even tell anything was done two days later."
The fact that the CelluTome creates very little donor-site inflammation also makes it helpful in addressing wounds left by pyoderma gangrenosum, after appropriate pharmaceutical treatment,7 and perhaps in other conditions wherein inflammation contraindicates conventional skin grafting, he said.
Because the procedure creates minimal donor-site disruption and is easy to perform, Dr. Kirsner has used it in other indications including sickle cell ulcers and nonhealing wounds in an elderly male treated for several squamous cell carcinomas.
Conversely, the Xpansion Micro-Autografting Kit (SteadMed/Applied Tissue Technologies) minces harvested skin to create 0.8 mm x 0.8 mm split-thickness skin grafts that can cover an area 100 times the size of the original graft. Because there's no need to orient the micrografts dermal side down, said Dr. Kirsner, "Those cells 'take,' or flip over, on their own," boosting the wound's healing capability.
Somewhat similarly, he said, using hair-transplantation techniques provides better stimulation of wound healing than traditional pinch biopsy techniques, perhaps because hair follicles contain factors such as stem cells. Presently, Dr. Kirsner and his colleagues are studying the interface between hair follicles and wound healing. "We believe that they share many of the same mechanisms, and some of the information and hair biology that we've learned from hair diseases can be applied to wounds."
To improve the quality of conventional skin grafts, Dr. Kirsner added, "pre-wounding" donor-area skin appears helpful.8 In two patients with chronic leg ulceration, "We took pinch biopsies, creating wounds, but didn't harvest the skin. We covered it for three days, which turned on the healing process in the grafts, then transferred them onto wounds." Pre-wounded grafts achieved marked improvement in ulcer-bed granulation tissue, and increased edge advancement.