Study of skin reconstruction by using tissue engineering technique

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Cultured epithelium and cultured dermis in particular have considerably preceded regeneration of other organs in the field of regenerative medicine. Some reasons why regeneration of epithelial tissue has preceded regeneration of other tissues seem to be that epithelial tissue has the structural advantages of being two-dimensional and needing no rigid scaffold as well as being anatomically simple as compared to other organs and tissues. With regard to keratinocytes, somatic (adult) stem cells have been found to be present in hair roots. Another reason is that it is relatively easy to harvest the stem cells. We have already transplanted cultured keratinocytes to treat large skin defects in at least 500 patients. The regenerated epithelium must be separated from the dish base for grafting. It is usually separated from the dish base with a proteinase, and for grafting the separated sheet is placed on a carrier prepared by molding in the same shape as the dish. There would be no problem if the epithelium sheet were strong enough to pick up with tweezers, but it is impossible to pick up the separated regenerated epidermis sheet with tweezers directly, and a carrier is required for application of the separated regenerated epithelium from the dish to the skin graft bed in clinical practice. Furthermore, because regenerated epithelium lacks a dermal component, epithelium grafting alone cannot produce good results in areas where there is a dermal defect. The facts mean that dermal elements are required for take of epithelium graft. To solve these problems, we have developed a technique designed to avoid the influence of protease released by keratinocytes and to increase the physical strength of fibrin itself, by mixing a certain protein with fibrin scaffold (Patent pending).