Oral cyclosporin A restores hair growth in the DEBR rat model for alopecia areata

Summary The Dundee experimental bald rat (DEBR) undergoes hair loss associated with the development of peri‐ and intrafollicular mononuclear cell infiltrates, as occurs in human alopecia areata. We studied the effect of orally administered cyclosporin A (10mg/kg; 5 days/week for 7 weeks) on established lesional DEBR rats displaying extensive areas of hair loss. New hairs appeared after 10 days and there was simultaneous regrowth of hair over the whole body with restoration of a full pelt by 5 weeks. Semiquantitative histological examination of flank skin biopsies revealed early reduction of the cellular infiltrate associated with conversion of dystrophic anagen follicles to normal, hair‐producing follicles. These results confirm the value of the DEBR model of alopecia areata in evaluating existing and new therapies for this disease in humans.