BY PLUCKING out a few hairs, doctors can grow skin grafts from a patient鈥檚
own cells.
The technique could replace the painful method of taking skin from another
part of the body for grafts or tissue culturing, Modex Therapeutics of Lausanne,
Switzerland, told a conference in London last week. 鈥淲e鈥檙e changing patients鈥�
hair to patients鈥� skin,鈥� says Edward Baetge, the company鈥檚 chief scientific
officer.
Called Epidex, the technique uses the stem cells found in hair follicles,
which can be transformed into skin cells. 鈥淒octors can pluck hair from any point
on the body,鈥� Baetge says. Then they send between 20 and 100 individual hairs to
Modex by post. The company grows the skin and sends it back in as little as a
month.
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The technique compares very favourably with other tissue culture techniques
that are available or under test at present, says Tania Phillips, a
dermatologist at Boston University School of Medicine. 鈥淚f you can do it by
pulling out a few hair follicles, that鈥檚 wonderful,鈥� says Phillips.
鈥淚t鈥檚 a great development because to get cultured keratinocyte grafts from
individual patients, you must take at least 1 centimetre of skin,鈥� she says.
鈥淲ith the hair cells, it sounds like you can provide skin coverage without
hurting the patient.鈥�
Thomas Hunziker and Alain Limat originally developed the technique at the
University Hospital skin clinic in Berne. They discovered that they could grow
skin cells from stem cells and other versatile 鈥渢ransient amplifying cells鈥�
taken from a part of the follicle known as the outer root sheath.
In the latest version of the process, the stem cells are deposited onto
trays, which are placed above a layer of unrelated human skin cells. These
secrete growth factors that transform the stem cells into basic skin cells
called primary keratinocytes.
If the patient is too sick to be treated, the keratinocytes can be frozen
until he or she is ready. Otherwise, the next step is to expose the cells to
air. This turns the layer of cells into proper skin, with a horny layer on top,
a basal keratinocyte layer at the bottom, and stratified epithelium in
between.
The company sends back discs of skin about 1 centimetre across and a tenth of
a millimetre thick. The discs are applied to half the damaged area, and grow to
cover the entire wound in about three months.
Last week, Modex released preliminary results of a trial on 80 patients with
diabetic ulcers at 12 clinics in Germany and Switzerland. For the first 36
patients to be treated, the company says the technique has worked at least as
well as the traditional grafting technique, called split skin mesh grafting.
Baetge says that the results are very encouraging. He adds that while the
technique is being tested only on fairly small ulcers, Modex is looking into its
potential for treating larger wounds.