Chapter 79 - Tissue-engineered skin products

Abstract

The culture of skin cells in organotypic systems has a comparatively long history, and such constructs have been seen as the simplest tissue-engineered products to fabricate. Accordingly, they were among the first tissue-engineered products that reached the commercial market. This has brought the realization of many other factors, apart from materials and culture considerations, which are involved in the production of a successful commercial product. These include the choice of scaffold, cell sources, particularly the use of allogeneic cells, design of bioreactor, automation of the manufacturing process, cryopreservation, and distribution. Manufacturing takes place in a highly regulated environment, which imposes many constraints on design and strategic planning. These concepts are illustrated with the processes involved in the manufacture of Dermagraft and TransCyte, taken as specific examples, including brief discussion of clinical trial experience and commercialization. Commercialization, at this point, involves, among other factors, satisfactory clinical trial results, demonstrating efficacy, an adequate rationale for the mechanism of action of the product and an established reimbursement system from third-party payers. The principles covered in this discussion are summarized. To this point, therapeutic tissue-engineered skin products have involved fibroblasts alone or fibroblasts and keratinocytes. In the future, we may expect to see products involving structures, such as hair follicles, which represent one of the few examples of organogenesis from adult cells, and the development of alternative methods of stasis preservation, such as desiccation. This approach is distinct from methods using autologous cells and three-dimensional printing, which are not scaleable and not discussed here.