Development of culture techniques of keratinocytes for skin graft production

The in vitro cultures of human tissues have attracted a great deal of medical attention as a promising technique for repairing defective tissues in vivo. In the last decade many companies have been established for supplying the regenerated grafts by means of tissue cultures of skin, cartilage, bone and so on. From the viewpoint of biochemical engineering, however, the culture systems for these tissues are not so sophisticated nor so programmed as the submerged culture systems developed for microorganisms. In manufacturing skin grafts, for instance, the raw materials of cells harvested from patients are heterogeneous, and the products of cultured tissues vary in the required size for individual epithelial sheets. Therefore, a reliable and robust process is desired for the production of cultured tissues with high reproducibility and quality. This review focuses on the strategies for developing the culture processes of keratinocytes targeting the epithelial sheet production, including (i) the introduction of culture techniques for keratinocyte cells and survey of skin graft production as it is, (ii) construction of kinetic model of cell growth, (iii) evaluation of cell properties based on image-analyzing techniques, and (iv) design of bioreactor system.