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Regenerative Medicine

Autologous Cultured Epidermis

Cultured Epidermis
Cultured Epidermis

Skin covers the human body completely. An average adult has a total surface area of around 1.6 m2 of skin, which if subcutaneous tissue is included weighs around 9 kg. Skin is the largest organ of the human body. If a burn or other trauma results in skin loss over a wide area, this seriously impairs its vital functions of maintaining body temperature and conserving fluid, and infection by bacteria that invade the body from outside also increases the risk of death. Histologically, skin comprises three layers: from the outside in, these are the epidermis, dermis, and subcutaneous tissue. The keratinocytes that compose the epidermis possess an extremely high ability to proliferate, meaning that skin regenerates very rapidly. When skin is lost over a wide area, however, regeneration takes too long. A cultured epidermis had been developed that can be grafted onto the injured area, made by isolating keratinocytes from a skin biopsy, culturing them in flasks, and forming them into a skin-like sheet.

When cultured epidermis grown from the patient's own cells is grafted, it does not provoke immune rejection but becomes the patient's own skin. Cultured epidermis was originally used to save the lives of patients with severe burns, but the outstanding speed with which it can close wounds, as well as its usefulness in skin pigmentation disorders (thanks to its incorporation of melanocytes*) swiftly became apparent. It was soon being actively used in the treatment of scars, vitiligo, nevi(birthmarks), ulcers, skin-graft donor sites, and other disorders. J-TEC produces cultured epidermal sheets for the treatment of severe burns.

*Melanocytes: Melanin-producing cells that exist in the basal layer of the epidermis.

Development

In the 1970s Professor Howard Green of Harvard Medical School developed a method that involved culturing keratinocytes together with mouse fibroblasts* to form a kera-tinocyte sheet, a method now known as Green's technique for culturing epidermis. In 1984 it attracted worldwide attention when the lives of two severely burned children were saved by this technique, which was used to generate 5000-7000 cm2 of cultured epithelium for grafting from what little skin remained to them. Many TEMPs are already available worldwide, and cultured epidermis prepared by Green's technique has invariably played a major role in advancing the development of regenerative medicine in different countries.

*Mouse fibroblasts: The 3T3-J2 cell line most favorable to keratinocyte cultivation according to the technique established by Professor H.Green. Their clinical safety has been confirmed in over 20 years of clinical use.

The technology for keratinocyte cultivation has been transferred to J-TEC by Professor Minoru Ueda of Nagoya University. J-TEC members have accumulated their expertise under the guidance of Professor H.Green, who developed the technique, and clinical authority Dr. Michele De Luca, and possesses the skills to generate cultured epidermis using Green's technique to meet the highest global standards.

Culture

By isolating keratinocytes from a 1-cm2 skin sample and culturing them as illustrated below, a sheet of cultured epidermis measuring around 1000 cm2 can be produced in around two weeks.

Transplantation of autologous cultured epidermis

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