INDUCTION OF HAIR-GROWTH IN EAR WOUNDS BY CULTURED DERMAL PAPILLA CELLS

In the adult hair follicle the dermal papilla plays a crucial role in the dermal-epidermal interactions that control hair production and eve nts of the growth cycle. It has previously been shown that cultured ce lls from rat vibrissa follicle dermal papillae can stimulate hair grow th when implanted into amputated follicles. This study investigated th e effects of implanting low-passage cultured papilla cells into small incisional wounds in the rat ear pinna. The groups of fibers that emer ged from wound sites were much larger than local hairs, and often had vibrissa-type characteristics. Later-passage papilla cells or cultured skin fibroblasts failed to elicit the same response. Histology reveal ed that big follicles were formed when papilla cells were trapped betw een the cut edges of the epidermis. Abnormally large follicles were se en at wound sites many months post-operatively. Independent of epiderm al influence, cultured papilla cells in the wound dermis formed rounde d papilla-like aggregates that also persisted until biopsy. A previous ly described method of wrapping papilla cells in glabrous epidermis wa s less successful in percentage terms but resulted in the production o f one very large vibrissa-type follicle and fiber. These results furth er illustrate that the inductive powers and developmental information retained by cultured dermal papilla cells parallel the properties of t heir embryonic precursors; the findings may have implications for huma n hair growth.