The establishment of optimum culture condition for keratinocytes from human adult skin, and an attempt to graft cultured epidermal sheets onto athymic mice.

An optimum culture condition was established for our keratinocyte cell culture system from human adult skin using 3T3 feeder cells. Calcium ion (Ca(+)+ concentration was found to be critical and cells grew best at the Ca(+)+ concentration of 0.2 mM. Keratinocyte proliferation was promoted when 0.4 micrograms/ml hydrocortisone and 7 micrograms/ml insulin were added. However, epidermal growth factor, cholera toxin and transferrin did not show stimulating effects on multiplication of human keratinocytes in our culture system. The epidermal sheets grown in vitro under this optimized condition were transplanted onto athymic mice, and a short term of take was observed.