CHEMICAL AND PHYSICAL-PROPERTIES OF COLLAGEN IMPLANTS INFLUENCE THEIRFATE IN-VIVO AS EVALUATED BY LIGHT AND CONFOCAL MICROSCOPY

Porcine collagen membranes having a rough and a smooth side were used for subcutaneous implantation studies in rats. Two tanning protocols w ere used for the membranes, a new one involving microwaving and glutar aldehyde treatment (NEWGA), and the other, a conventional method using glutaraldehyde treatment at room temperature (OLDGA). Untreated membr anes (NONGA) were also implanted. Sections of the implants were examin ed by light microscopy and with the confocal laser scanning microscope focusing on neovascularization and incorporation of the implant. At 6 4 days, the smooth sides of NEWGA and OLDGA implants were not well inc orporated, with scarring subjacent to the surface and dystrophic calci fication of that side of the membrane. At the same time, the rough sid es of the NEWGA and OLDGA were not calcified with a giant cell reactio n around the porcine collagen. The best incorporation was found in the NONGA membranes with no dystrophic calcification, excellent neovascul arization of all layers, and complete remodeling at day 64. After 5 mo nths, the completely remodeled NONGA membrane still could be identifie d, and the NEWGA and OLDGA membranes were calcified with a giant cell reaction having a dense fibrous capsule. It is concluded that if cross -linking is deemed necessary, the microwave cross-linking method is ad visable because in the early stages there is less reactive inflammatio n around it, and the implant surfaces should be rough with an open str ucture, making calcification of crosslinked collagen unlikely. (C) 199 4 John Wiley and Sons, Inc.