Improved spontaneous endothelialization by postfixation treatment of bovine pericardium

Abstract

The longstanding release of locally cytotoxic glutaraldehydeconcentrations from fixed biological materials is one reason for the lackof spontaneous endothelialization in vivo and in vitro of biological grafts(and valves). Preliminary studies have shown that bovine pericardiumpostfixation-treated with aminoacids may be endothelialized in vitro. Totest whether such treatment improves spontaneous endothelialization in vivo8 cm long segments grafts (6 mm I.D.) were interposed into the carotidarteries of 10 sheep. Ten grafts were sewn from postfixation treatedpericardium (PTP), 4 from standard glutaraldehyde fixed pericardium (GAP)and 6 polytetrafluoroethylane (PTFE) grafts were implanted to study thedegree of spontaneous endothelialization. In two pregnant animals, allgrafts occluded (2 PTP, 1 GAP, 1 PTFE). In the remaining animals 1additional PTFE graft occluded and 2 PTFE and 1 GA grafts showedsignificant thrombotic obstruction. The patent grafts were harvested at 3months and the surface covered with red thrombus was determined byplanimetry. PTP grafts had significantly less (12.2% +/- 15%) thromboticappositions than glutaraldehyde treated grafts (49% +/- 20%; P = 0.01) andPTFE grafts (40.5% +/- 13%; P = 0.01). In the central areas of the PTPgrafts, endothelial cells spread directly on the collagenous matrix andproduced a basal lamina. In GAP, endothelial cells spread on amorphousmaterial or macrophages and in PTFE grafts, only a neointima composed ofmyofibroblasts was endothelialized. Neutralization of glutaraldehydeconcentrations by postfixation with aminoacids improves spontaneousendothelialization in vivo in biological materials.