Although a tremendous progress has been made, large full-thickness skin defects are still associated with mortality due to a low availability of donor skin areas.
Autologous cultured epidermal autografts (CEA) were first to be used as an epidermal substitute; however, their functional and esthetic results were unsatisfying due to graft contracture, scars, and infections. The addition of a cellular dermal component to those skin substitutes resulted in an improved function and esthetic appearance. These improvements are due to the presence of fibroblasts, which produce extracellular matrix (ECM) proteins such as collagen, elastin, laminin, and fibronectin that provide a mechanical stability to the dermis and regulate the function of cells in the epidermis, keratinocytes and melanocytes. Recently, dermo-epidermal tissue-engineered skin substitutes (DESS) emerged as an alternative in the treatment of deep burns and various skin-related disorders mimicking a near-natural skin appearance with regard to the skin texture, color, and mechanical properties.
Due to the shortage of skin donor sites following large full-thickness skin injuries, new cell sources have been exploited for skin tissue regeneration. Adipose tissue represents an abundant and easily accessible source of adult stem cells for translational clinical approaches including skin tissue engineering. The stromal vascular fraction (SVF) is a freshly isolated heterogeneous cell population, which is derived from excised adipose tissue or liposuctions. The SVF may be further used for selection and expansion of an adherent population, so-called adipose-derived stem cells (ASCs). The ASCs are characterized by the expression of specific markers and their ability to differentiate into cells from meso-, ecto-, and endodermal lineages. However, recently introduced new nomenclature, isolation protocols, culture techniques, and differentiation methods lack standardization and may lead to misunderstandings.
Adipose-derived stem cell therapy has gained tremendous interest in the area of skin repair and regeneration as a new paradigm for skin function restoration after injury. Compared to BMSCs, sufficient number of ASCs can be obtained from a relative small amount of adipose tissue during a minimally invasive harvesting procedure. Therefore, ASCs are recognized as an attractive substitute for BMSC for therapeutic applications.
However, apart from the numerous in vitro and in vivo studies demonstrating the high therapeutic potential of ASCs, the lack of standardized cell isolation methods as well as culture and differentiation protocols need to be overcome to advance the clinical utility of these cells. Moreover, additional safety studies and quality controls tests are necessary to translate scientific findings from basic science into the standard skin wound care plan in the clinic.