The Healing Arts Embrace Materials Science

Recent advances in NSF-supported biomaterials research are hastening the development of innovative healing aids. Researchers at Georgia Institute of Technology, California Institute of Technology, and Massachusetts Institute of Technology (MIT) are working with physicians and biological specialists to develop polymer composites for patching wounds, biocompatible casings for cell transplants, scaffolds that guide and encourage cells to form tissue, bioreactors for large-scale production of therapeutic cells, and experimental and theoretical models that predict behavior of these materials in vivo. Biomaterials have already been developed to block unwanted reactions between transplanted cells and host tissue and to help prevent scarring during healing. Closest to commercialization is a polymeric material, synthesized at MIT, to which biological cells can adhere. Because the human body accepts biological cells while it might reject the overlying synthetic material, this breakthrough makes possible the development of inexpensive multilayer materials that can promote healing, act as artificial skin, or temporarily replace connective tissue until the body can produce natural tissue to complete the healing process.

Another NSF-supported technology for skin replacement, developed by Ioannis V. Yannas of MIT and his colleagues, received FDA approval in 1996. The Yannas technology addresses the challenge of treating severe burns that result in the loss of dermis, a layer about two millimeters thick that lies beneath the epidermis and does not regenerate when damaged. Traditionally, patients with such severe burns receive skin transplants from sites elsewhere on their bodies, a method that results in scarring. The new technology involves collagen taken from animal tendons. Collagen is part of the structural scaffolding in mammals (analogous to cellulose in plants) that allows tissues to maintain their shape. This collagen is chemically bonded with glycosaminoglycan (GAG) molecules, from animal cartilage, to create a simple model of the extracellular matrix that provides the basis for a new dermis. The collagen-GAG combination "makes a simple chemical analog of the matrices in our own tissues," Yannas explains. GAG cells synthesize a new dermis at the same time that the scaffold is being broken down. Epidermis then grows naturally over the new dermis, unless the wound area is especially large. Patients end up almost completely free of disfiguring scars. The new skin also grows as the patients do, an important consideration for children who have been burned.