Background and Objectives: Micrograft transplantation is accompanied by a transient induction of telogen in transplanted hair follicles (HF), which might be avoided by supporting the metabolic pathways of the micrograft during the ex vivo period. Vitamin B 12 (cobalamin) has been suggested to influence HF growth and cycling in humans, but the mechanisms are unclear. Method: HFs were obtained from patients undergoing routine micrograft transplantation and were cultured for 5 days in Dulbecco's modified Eagles Medium, supplemented with different amounts of vitamin B 12. Hair shaft elongation (HSE) of the isolated HFs as well as quantitative changes of mRNA for -catenin, glykogensynthase kinase-3 (GSK-3) and TCF/Lef-1 in HF cells were determined. Results: In vitro HSE demonstrated a dose dependent induction of HSE after stimulation with 2.5 g/ml and 25 g/ml vitamin B 12 (6.2  2.1% and 15.4  3.8% respectively). A dose dependent induction of -catenin-mRNA could be demonstrated in cultured HFs after stimulation with 2.5 g/ml and 25 g/ml vitamin B 12 (fold change compared to DMEM: 9.5  2.7, p < 0.05 and 23.1  7.4, p < 0.01; respectively). Concomitantly the amounts of GSK-3 were significantly reduced after stimulation with 25 g/ml vitamin B 12 (fold change compared to DMEM: 0.76  0.12, p < 0.05). Conclusions: Our data demonstrate a hair growth promoting effect of vitamin B 12 in vitro. This effect is accompanied by the modulation of intracellular signal transduction molecules of the wnt-pathway and might promote hair growth after micrograft transplantation.

These data clearly demonstrate a reduction in the specific function of cells in the DP, which seem to be the causative for the induction of hair follicle cycling during micrograft preparation and storage.

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