In Vitro Culture Methods of Skin Cells for Optimal Skin Reconstruction by Tissue Engineering

Replacement of a wounded or destroyed tissue is now technically possible using an in vitro method of tissue engineering. This method involves isolating and culturing human cells (autologous or not) in optimal conditions to form a reconstructed tissue with similar characteristics to its in vivo counterpart. Burn victims were the first patients to benefit from this method in 1981, wherein reconstituted human epidermal tissues were used to treat the burns (O'Connor et al., 1981). The pioneered technique comprises epidermal cell isolation, culturing and grafting as a unique layer of cells organized in a sheet. The differentiation of the cells into a pluristratified epidermis is performed in vivo after grafting. Numerous improvements, most notably the addition of a dermal part in skin tissue reconstruction have been made since the technique’s inception. However, the dermis is more difficult to reconstitute because of the complexity of its organization. Briefly, the dermis is a mix of matrix and cells, which are primarily fibroblasts. Moreover, the dermis is also composed of several structures such as the epidermal annexes (e.g., hair and sebaceous and sweat glands) and a network of capillaries. Several others cells like lymphocytes, or neurons are also more difficult to add on dermis despite their crucial roles in acquiring all the functions of the skin. Furthermore, the third part of the skin, the hypodermis is vital in vivo and addition of this tissue will increase the function of the grafted skin. In classical cutaneous grafting with splitor full-thickness skin, the amount of dermis that is grafted to a wound bed inversely correlates with the degree of scarring and wound contracture which impacts the functional and cosmetic outcome (Bombaro et al., 2003). Similarly, dermal cells have been fundamental in the efficacy and quality of cultured keratinocyte grafts (Moulin et al., 2000) (El Ghalbzouri et al., 2002) (Kirfel and Herzog, 2004; Gallant-Behm et al., 2011) (Robert et al., 1997). Currently clinics widely use dermis that is constituted of matrix and fibroblasts. The methods used to obtain cultured living dermis, which can be grouped into three different categories (Table 1) represent the three main methods of tissue engineering. These categories are based on the materials used to originate the matrix, such as biomaterials, biological materials and dermal fibroblasts. Biomaterials are materials that are not present in skin but