A Primary Study Of β-NGF And P75NTR Synthesized By Hair Follicle Stem Cell In Early Stage Of Wound Healing

Hair follicle (HF) is a complex epidermal appendages composed of three kinds of cells including epithelium, neural ectoderm and interstitial cells. These cells located in inner root sheath (IRS), outer root sheath (ORS), hair shaft (HS) and dermal papilla (DP). Therefore HF is a very significant study model in the interaction of epithelium and mesenchyma in developmental biology.On the basis of HF development we could divide HF cycle into four stages, i.e. anagen, catagen, telogen and a putative active exogen. In early anagen epithelium of hair bulb and dermal papilla (DP) downgrowth into epidermis at the same time keratinocytes (KCs) differentiate into every kind of HF cells. Up to catagen KCs suddenly cease generation and begin to regress, inner- and extracellular matrix degradate, DP condensely arise close to everlasting apartment, bulge. After this HF steps into telogen, a stage of hair cycle. Not only changes occurred in HF morphogenesis but also development and growth in every stage are regulated by many signals and factors.Cotsarelis et al discovered there were no labeling cells and characteristic of stem cells in hair bulb but bulge of skin, eyelashes and vibrissa in mouse. However labels were in hair matrix when using out-burst labeling based on which he later proposed bulge-activation hypothesis. Rochat et al found bulge KCs were able to yield larger colonies than those from other skin sites when cultured in vitro. In 2000, Taylor et al confirmed that hair follicle stem cells (HFSCs) located in bulge of upper follicle when using Brdu and 3H double labeling method. Nowadays, the niche of HFSCs is restricted to bulge. Meanwhile several laboratories strongly made clear the characteristic and classification of HFSCs, providing theory basis and experimental foundation. These study results suggested that there are some undifferentiated, slowly cycling and in vitro potential proliferational stem cells (SCs) in HF bulge. Morris et al discovered k15 promoter with specific activity in adult bulge cells, which could be labeled and tracked using and inducible lineage analysis system. These cells and their progenies could give rise to all of the epithelial layers of the newly generated...