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

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 (10 mg/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.