Peribulbar innervation and substance P expression following nonpermanent injury to the human scalp hair follicle

The hair pluck procedure alters the anatomy of the anagen hair bulb. Hemmor hage can occur in the mesenchymal sheath and breaks at the proximal epithel ium, above or around the upper third of the dermal papilla, have been repor ted. We hypothesized that innervation, as identified with protein gene prod uct 9.5 (PGP 9.5), and expression of the neuropeptide Substance P (SP) with in the dermal papilla would also be altered following plucking. We focused on studying SP as this neuropeptide has been associated with several cellul ar responses, including anagen hair growth in the C57BL/6 mouse model. Four millimeter punch biopsies were obtained from the occipital scalp of two he althy adults. Hair was then plucked and additional biopsies were obtained i mmediately, and at 1 d, 1 wk, and Imo after plucking. Each set was processe d for immunohistochemical analyses and in-focus optical sections of the der mal papilla were captured by laser scanning confocal microscopy and later r econstructed into single images. Following injury, SP was expressed in a di sorganized pattern below the dermal papilla, There was also a significant r eduction in labeled neuronal cells, and SP expression was enhanced within p eribulbar blood vessels at Id and 1 wk, By 1 mo, peribulbar nerves, vessels , and SP expression were similar to baseline observations. It remains to be ascertained whether PGP 9.5, also known as unbiquitin hydrolase, and SP ar e involved in the proliferation of new matrix cells in the human scalp hair follicle following injury.