Epidermis Grafting: From Adult to Embryonic Stem Cells

Abstract

Cell therapy has radically changed the lives of burn victims. For more than two decades, cellculture techniques have been used in order to obtain a sufficiently large areas of skin to reconstruct the destroyed epidermis from a small sample harvested from the patients themselves [1]. Although this type of graft is used successfully, one of its limits is the 3 weeks required to produce a sufficient amount of epidermis to cover the affected areas, leaving the patient unprotected during this interval [2]. For several years, research has led to the development of skin substitutes to protect patients during the period before grafting. Standard temporary skin includes the use of cadaver skin or de-epidermized pig skin. Because of the burn victim’s immune system activation, these types of grafts can potentially be rejected. For this reason, these biological tissues are only used as temporary biological wound dressings. Synthetic and biosynthetic matrices containing adult allogenic skin cells and bovine collagen are alternatively proposed without a guarantee of the necessary safety, especially in terms of graft rejection and presence of contaminants [3]. Rapid access to an unlimited source of epidermal cells from human embryonic stem cells (hESCs) that can reconstitute an epidermis, perfectly controlled in the laboratory before use, would therefore be one solution to the problems posed by existing techniques. In this context, researchers at the Institute for Stem cell Therapy and Exploration of Monogenic diseases (I-STEM; Evry, France), a laboratory of the French National Institute of Health and Medical Research (INSERM), have devised a pluristratified epidermis using keratinocyte-derived hESCs (K-hESCs). I-STEM was opened on 1 January 2005. It is a center for research and development, dedicated to the development of treatments based on the potential of pluripotent stem cells and their applicability to rare diseases of genetic origin. Defined by three key phrases ‘therapeutics’, ‘monogenic diseases’ and ‘pluripotent stem cells’, the activity of I-STEM extends from basic biological research and pathological mechanisms up to the transfer of new therapies to clinical research.