UCSD OKs Test of New Skin Graft Technique

A pair of researchers who believe they have developed a way of growing large quantities of skin from small samples have received permission from UC San Diego Medical Center to go ahead and apply the technique to victims of third-degree burns.

The skin-replacement technique, approved for a two-year trial run, differs from current methods in that doctors believe they can achieve up to a six-hundredfold expansion of grafted skin, rather than the sixfold expansion achievable by conventional methods.

“The advantage is that for any amount of area that would need to be grafted, a smaller amount of tissue is needed to begin with,” said Steven Boyce, a molecular and cellular biologist who developed the method. “So the amount of donated tissue is reduced in all cases. . . . There’s less injury inflicted to the patient.”

Conventional techniques for closing “full thickness burns,” in which all of the outer and most of the inner skin is destroyed, usually allow for a 1.5-to-1 or 3-to-1 expansion, Boyce said. If a large percentage of a person’s body surface area is burned, there may be not be enough undamaged skin left for grafting.

Under the technique developed by Boyce and Dr. John Hansbrough, the skin cells grow much more rapidly into so-called cell sheets. Boyce said they grow quickly in part because of a specially formulated “nutrient medium” in which the cells are cultured in a lab. They also can be frozen, he said.

“So the cells can be proliferated, stored in liquid nitrogen and recovered with very high efficiency,” Boyce said.

The technique allows for replacement not only of the outer epidermal layer but also of the inner skin, in order to replace the full thickness of the skin. The cultured cells are combined with an inner-skin replacement based on collagen, Boyce said.

Collagen, the major structural protein in the body, is taken from animal tissues because of their availability, Boyce said. It serves as a structural framework into which blood vessels and connective tissues from the wound can grow.

This summer, Boyce and Hansbrough, who is director of the regional burn center at UCSD Medical Center, applied to the university’s Human Subjects Committee for permission to try their experimental procedure on patients. Approval requires proof that the proposal offers a substantial benefit when weighed against risks and that the risks are minimal.

Boyce said they backed up their application with the results of laboratory work they have done over the past three years at the University of Colorado and UC San Diego. He said the technique “appears to work on animals,” but he declined to discuss the experiments done with animals.

In August, the university committee voted to approve the proposal. Boyce said he could not predict when he and Hansbrough would first apply it to a patient. He said that will happen when they are satisfied that it will work, adding: “We’re getting close.”

The initial applications are expected to involve people with small, deep burns who are otherwise healthy, Boyce said. Ultimately, the technique would be applicable in any case where skin grafting is required, burn cases being the most prominent example.

However, before the technique can be used widely, Boyce said, much more study will be required. Among the questions that need to be answered are how the healed wounds hold up over time and whether they “are superior in their function and appearance compared to conventional techniques.”

“Those are the kinds of things that have to be answered before the techniques become a convention,” he said. “They remain experimental until those things are answered. Those kinds of studies take a long time.”