the present invention relates to a hydrated , biocompatible tissue - augmentation compound and methodology for its implantation into mammalian tissue . the tissue - augmentation compound is comprised of : living tissue , optionally body derived fluids , and at least one nco - terminated hydrophilic urethane prepolymer derived from an organic polyisocyanate , and oxyethylene - containing diols or polyols in which essentially all of hydroxyl groups are capped with polyisocyanate .