In an advance that may pave the way for development of human tissue replacements, a biodegradable polymer has been synthesized that could function as a matrix to support mammalian (including human) cells. University researchers recently synthesized the copolymer of lactic acid and lysine and chemically attached a biologically active peptide to it. The Federal Government supported the research. Progress in tissue engineering hinges on the development of matrix materials that are biodegradable and compatible with cell function and have adequate adhesive properties.