Epidermolysis bullosa -: A genetic disease of altered cell adhesion and wound healing, and the possible clinical utility of topically applied thymosin β4

Inherited epidermolysis bullosa (EB), having an overall incidence of only about 19 in every 1 million live births, encompasses many phenotypically and genotypically distinct diseases characterized by the presence of recurrent blisters, mechanical fragility of the skin and other epithelial structures (most notably the cornea and gastrointestinal tract), and scar formation. Each disease is the result of mutations within any of 10 specific structural proteins (keratins, laminins, collagens, integrins) within the basilar keratinocyte or the skin basement membrane zone. Two of the more severe subtypes, junctional and dystrophic EB, often involve many extracutaneous tissues. If severe, these conditions may be life threatening. Recent studies in wounds that had been artificially induced on normal skin, both in rodents and in human volunteers, have suggested that thymosin beta 4 may be effective in promoting epithelial migration across the wounds. A randomized double-blind clinical trial has been recently organized to determine whether this novel biologic agent may be beneficial in promoting wound healing in patients with junctional and dystrophic EB. To do so, a solitary noninfected cutaneous wound of standardized size will be treated topically on a daily basis with either one of three concentrations of thymosin beta 4 or a placebo control. Serial wound healing will be quantitated by computerized digital-imaging technique. At the same time, the occurrence of adverse effects will be sought, so as to confirm the safety of thymosin beta 4 when applied to EB skin, both in children and in adults. Although as yet unproven, topically applied thymosin beta 4 may prove to be an extremely important addition to the overall management of patients with this potentially devastating disease.