Copyright © 2015 American Society of Plastic Surgeons. Unauthorized reproduction of this article is prohibited. www.PRSJournal.com 1740 B iomaterials include some of the oldest medical technologies still used in modern clinical practice today. The word “biomate- rial” implies the ability of this active material to become incorporated into native tissue. Today, this term encompasses an ever-growing list of products and categories derived from both human and animal tissue, and synthetic mate- rials derived from naturally occurring organic substances. Because of the sheer scope of the topic, we have created a targeted review on the most relevant and recent clinical studies, with an emphasis on levels of evidence, to highlight the current state of the technology, identify areas where strong clinical data are lacking, and sum- marize recent key findings. BASIC SCIENCE Biomaterials, whether derived from human tissue, animal tissue, or naturally occurring resources, can be distinguished from purely syn- thetic materials by their tendency to become degraded or to be incorporated into a host’s tis- sue. This biocompatibility is thought to result in a minimal foreign body reaction characterized by increased integration and vascularization, release of antiinflammatory cytokines, improved bacte- rial clearance, and improved healing compared with synthetic materials. 1 It is the goal of current basic science research to enhance wound healing by optimizing the design of biomaterials. 2 The shared component of acellular dermal matrix and hyaluronic acid–based gels, the two most commonly used biomaterials, is the presence of a three-dimensional collagen matrix. As such, shifts in focus on design elements such as pore size, mechanical integrity, and tension have emerged as critical features for cellular attachment, prolif- eration, and differentiation, and thus altering the wound healing dynamic. 3–5 DERMAL SUBSTITUTES AND BURN WOUNDS Autologous donor skin sources are often scarce and skin grafts can fall short in provid- ing stable coverage to restore the structure and function of skin. Evidence indicates that skin replacement requires a dermal layer or structural components that facilitate the generation of a dermal layer to optimize healing and reduce scar- ring and contraction. 4 As a result, a number of synthetic, natural, cellular, and acellular products Disclosure: The authors have no financial interest to declare in relation to the content of this article. Derek A. Banyard, M.D., M.B.A. Jenna Martin Bourgeois, M.D. Alan D. Widgerow, M.B.B.Ch., M.Med. Gregory R. D. Evans, M.D. Orange, Calif. Summary: The authors present a review of biomaterials, substances tradition- ally derived from human or animal tissue or, more recently, biodegradable synthetics modeled after naturally occurring resources. These constructs dif- fer from purely synthetic materials in that they are degraded or incorporat- ed into a host’s tissue. These biomaterials include a diverse array of medical products, such as acellular dermal matrix, bone substitutes, and injectables. In this review, the authors examine various clinical applications, including burn reconstruction and wound healing, breast surgery, complex abdominal wall reconstruction, craniofacial repair, and cosmetic surgery. Biomaterials such as acellular dermal matrix have proven beneficial in difficult-to-treat applications; however, more prospective data are needed to determine their true efficacy and cost-effectiveness. (Plast. Reconstr. Surg. 135: 1740, 2015.) Copyright © 2015 by the American Society of Plastic Surgeons DOI: 10.1097/PRS.0000000000001272 From the Center for Tissue Engineering, Department of Plastic Surgery, University of California, Irvine. Received for publication May 21, 2014; accepted December 16, 2014. Regenerative Biomaterials: A Review A Video Discussion by Geoffrey C. Gurtner, M.D., accompanies this article. Go to PRSJournal.com and click on “Video Discussions” in the “Videos” tab to watch. REGENERATIVE MEDICINE