SUCCESSFUL TREATMENT OF CHRONIC LEG ULCERS WITH EPIDERMAL EQUIVALENTSGENERATED FROM CULTURED AUTOLOGOUS OUTER ROOT SHEATH-CELLS

The outer root sheath cells of hair follicles can substitute for inter follicular epidermal keratinocytes, as during healing of skin wounds w hen these cells migrate onto the denuded area and contribute to epider mal regeneration, Using improved culture techniques, we generated epid ermal equivalents from cultured outer root sheath cells of patients su ffering from recalcitrant chronic leg ulcers, primarily of vascular or igin, In such epidermal equivalents, tissue organization as well as im munolocalization of epidermal differentiation products (keratin 10, in volucrin, filaggrin) and integrins were indistinguishable from normal epidermis. As determined by the number of bromodeoxyuridine-incorporat ing cells, the basal layer contained a large compartment of proliferat ive cells irrespective of donor age, FAGS analysis of the outer root s heath cells, used to prepare the epidermal equivalents, disclosed a fr action of small cells with enhanced expression of beta(1)-integrin, a potential stem cell marker. In contrast to acute wounds, a major defin itive take of grafted cultured autologous keratinocytes has not been c onvincingly demonstrated in chronic wounds. In a pilot study, grafting of epidermal equivalents generated in vitro from autologous outer roo t sheath cells on 11 ulcers in five patients resulted in a definitive take rate of about 80%, with subsequent complete healing within 2 to 3 wk of five out of seven ulcers grafted with densely arranged cultures , This improvement in the treatment of chronic leg ulcers with culture d autologous keratinocytes probably depends on the large compartment o f proliferative cells as well as on a well-developed horny layer which prevents disintegration of the grafts, Practical advantages of the ne w technique are its noninvasiveness, the lack of need for surgical fac ilities or anesthesia, and a short immobilization period after graftin g.