A randomized pilot study to compare hair follicle cell suspensions prepared using trypsin alone versus trypsin in combination with collagenase type I for transplantation in vitiligo

Background Noncultured extracted hair follicle outer root sheath cell suspension (NC-EHF-ORS-CS) is an upcoming surgical technique to treat stable vitiligo. Conventionally it employs trypsin to tap the hair follicle (HF) reservoir for autologous melanocytes and their precursors for transplantation. However, a perifollicular dermal sheath composed of type 1 collagen encases the target 'bulge' region of the HF. Adding collagenase type 1 would digest the ORS, facilitating better release of cells. Aim To compare the repigmentation achieved using trypsin and a combination of collagenase plus trypsin, respectively, with dermabrasion alone, and to compare cell counts, viability and composition of both suspensions. Methods This was a randomized, double-blind, comparative, therapeutic trial, conducted as a pilot study on 22 patients with stable vitiligo. Three similar patches were randomized into three parallel treatment arms [(A) trypsin plus collagenase, (B) trypsin alone and (C) dermabrasion with vehicle alone]. Each patient's HF sample was divided and digested by the two methods, and transplanted as suspensions onto dermabraded patches, while a third dermabraded patch received the vehicle only. Suspensions were sent for laboratory analysis. Repigmentation was assessed over a follow-up of 6 months. Results There was a significant increase in cell yield and comparable viability when collagenase was added. Immunohistochemical and flow cytometry studies showed a nonsignificant increase in HMB45+ melanocytes and their precursor stem cells in group A. This trend was reflected clinically in the extent of repigmentation [group A (33.22%) > B (24.31%) > C (16.59%); P = 0.13]. Adding collagenase induced significantly higher repigmentation than dermabrasion alone (P < 0.05). Conclusions Incorporating collagenase type I into the conventional NC-EHF-ORS-CS technique resulted in enhanced retrieval of pigment-forming cells and subsequently improved repigmentation in vitiligo.