The greatest problem with current breast prostheses is the development of a contractile fibrous capsule. Capsular contracture produces breast hardening, pain, and distortion of the breast shape. This SBIR Phase I project proposes to combine two types of prosthesis surface modifications to reduce capsule formation and contracture. First, the prosthesis to be used will have a textured (porous) silicone rubber surface. Porous polymers are reported to improve tissue integration, decrease the size of fibrous capsules formed, and inhibit the ordered formation of collagen/myofibril layers that are typical of contracted capsules. Second, the textured surface will be coated with extracellular matrix (ECM) proteins and/or peptides to further improve tissue integration by promoting the attachment and ingrowth of breast tissue. Radiolabelled ECM proteins and peptides will be used to optimize immobilization efficiency on the prostheses, and their bioactivity will be evaluated in vitro by quantitating the attachment and growth of fibroblasts and epithelial cells. Coated prostheses will be implanted subcutaneously into pigs and histologically evaluated for tissue integration and fibrous encapsulation. Mammary prostheses are the most commonly used synthetic implants in the United States, and about 30% of these prostheses encounter significant problems with capsular contracture. Therefore, prostheses modifications that reduce the incidence of this problem would be extremely beneficial.