Hair growth in scalp grafts from patients with alopecia areata and alopecia universalis grafted onto nude mice.

A basic question in both mild and severe forms of alopecia areata (AA) relates to whether the disease is inherent to the affected tissue or secondary to circulating factors. This question has been addressed by grafting 2-mm grafts of scalp from affected areas of seven patients with AA or alopecia universalis (AU) onto congenitally athymic (nude) mice. Hair growth in these grafts has been compared with that of 2-mm grafts from hair-bearing skin remnants from two individuals undergoing elective plastic surgical procedures. Because cyclosporine seems to directly affect hair growth, a group of grafted mice was treated with this agent. By day 48, hair growth was present in many surviving grafts. Cyclosporine affected hair growth; this was most prominent by day 78 when the number of hairs per graft and the mean length of hair had increased significantly over untreated groups. Grafts from patients with AU had more hairs per graft and had greater hair length than did similar grafts from patients with AA. These experiments show that hair growth ability in situ is likely normal in AA and AU, and that the factors causative to this disease in situ are mediated humorally. Furthermore, cyclosporine seems to directly influence hair growth in this model system.