# Decellularized Scaffolds for Skin Repair and Regeneration
## 2 Tissue Sources for Preparation of ECM-Based Biomaterials for Skin Repair
### Acellular Dermal Matrix (ADM)  
A decellularized dermal matrix is an acellular tissue made by taking a full-thickness section from a donor source, which in most cases is a human cadaver or of porcine or bovine origin. In the case of human donors, the tissue is screened for infectious agents, such as HIV, hepatitis, and syphilis [31]. In the last two decades, ADM has become increasingly popular for the coverage of soft-tissue open wounds. Artificial dermal substitutes are routinely used in the treatment of chronic and acute injuries, particularly when autologous intact cutaneous tissue is not available [32]. Although skin grafting is significantly less expensive, the use of ADM can be a successful alternative to a painful and aesthetically  
Figure 1: Schematic representation of tissue sources for the preparation of decellularized matrix to support skin repair and regeneration. Basic structure, composition and location of each tissue source are indicated for (**A**) Skin, (**B**) Peritoneum, (**C**) Small intestine submuca, (**D**) Ambiotic membrane.  
undesirable donor site [31]. In addition, as has long been recognized, the presence of dermis enhances the success of subsequent skin transplantation, inhibits granulation tissue formation, and prevents scar formation, thereby reducing vascular contraction [26]. Thus, ADM is often used in conjunction with split-thickness grafts for the treatment of full-thickness wounds [31]. Aside from burn wounds and diabetic foot ulcers (DFUs), more recently, ADMs have been suggested as a successful alternative to vascularized flaps for extremity wounds with exposed tendons, bones, and joints [32]. ADMs are currently produced and developed as various commercial products, and here we focus on commercially available skin substitutes with substantial relevant evidence of efficacy.  
The gold standard for temporary coverage is a skin allograft, i.e., the skin is transplanted from one person to another. As with autografts involving graft transfer from the same individual, allografts undergo vascularization within 2-3 days and can provide a variable barrier after a severe burn. Unlike autografts, however, the skin is highly immunogenic, and when a viable skin allograft is transplanted onto a healthy recipient, rejection occurs within 6-14 days [33]. Allograft ADM products derived from donated human skin are supplied by tissue banks compliant with standards of the American Association of Tissue Banks and FDA guidelines. A long list of products derived from minimally processed human donor tissue is available, with different durations of covering depending on their design and composition [34] including the following: AlloDermTM regenerative tissue matrix (RTM; LifeCell Corp., Branchburg, New Jersey, USA), AlloPatch HDR Pliable (Musculoskeletal Transplant Foundation), CymetraTM Micronized AlloDermTM (injectable form of AlloDermTM, LifeCellKCl), DermacellR (LifeNet Health), Flex HDR (Ethicon and Musculoskeletal Transplant Foundation), GammaGraftR (Promethean Lifesciences, Inc.), GraftJacketR RTM (LifeCell, licensed to Wright Medical Technology and KCl), GlyadermR (Euro Skin Bank, Beverwijk, The Netherlands), Matrix HDTM (RTI Biologics), MemodermTM (Memometal, Inc.), Puros DermisR (Zimmer Dental), and RepliformR (LifeCell and Boston Scientific) [35]. At least five different manufacturing processes and products (AlloDermTM, DermaMatrix, GlyadermR, GraftJacketR, and SureDermR) are currently registered for wound care (Table 1) [33]. We discuss here in detail the most cited versions considering their efficacy in treating burns and non-healing/difficult-to-heal wounds.