The hair follicle plays a pivotal role in cutaneous biology. As an epidermal appendage, it possesses a full complement of epidermal cell types, including keratinocytes, melanocytes, and Langerhans cells, which all reside in the follicle outer root sheath that is contiguous with the epidermis. When these cell types are lost from the epidermis (for example, through wounding, ultraviolet light, thermal or chemical injury), precursor cells proliferate and migrate out of the hair follicle to repopulate the epidermis. The ultimate source of keratinocytes and possibly melanocytes for repopulating the epidermis is thought to reside in the hair follicle bulge [1-4]. The bulge consists frontal baldness hair loss diseases of a cluster of biochemically distinct outer-root sheath cells which are located at the lowermost portion of the permanent follicle [2, 5]. Keratinocytes within the bulge have the characteristic properties of epithelial stem cells in that they are the longest-lived epithelial cells in the hair follicle [6], and they are biochemically distinct because they preferentially express cytokeratin 15 [5]. The bulge is also thought to give rise to the lower hair follicle matrix cells [2]. Thus, the targeting of cells within the hair follicle, and particularly the bulge, is a logical goal for those interested in gene therapy for the treatment of a avacor hair loss website hair loss diseases wide variety of cutaneous disease. Because of its accessibility, the skin may seem like an attractive target for topically delivered gene therapy. However, since the epidermis and stratum corneum are designed as barriers to prevent ingress of material such as bacteria and other infectious agents, the challenges of introducing genes into human epidermal cells are formidable. These difficulties are avoided by using an ex vivo approach in which cells are removed, transfected in vitro - usually with a viral vector, and reintroduced to the host. The major disadvantages of ex vivo strategies include the need to culture cells, which results in loss of baldness remedies hair loss diseases the tissue
