EARLY FLOW SURFACE ENDOTHELIALIZATION BEFORE MICROVESSEL INGROWTH IN ACCELERATED GRAFT HEALING, WITH BRDU IDENTIFICATION OF CELLULAR PROLIFERATION

The purpose of this report was to determine ii flow surface endothelia lization could precede microvessel ingrowth from the perigraft area in porous Dacron grafts, by using an accelerated graft healing model wit h short implant periods. Dacron grafts were implanted in the abdominal aorta of 22 dogs and wrapped in autogenous inferior vena cava (IVC), which provided excellent conditions for extramural angiogenesis, micro vessel development, and ingrowth toward the graft. Retrieval times wer e 7 days (n = 4), 8 days (n = 5), 9 days (n = 4), 19 days (n = 3), 11 days (n = 4) and 12 days (n = 3) postoperatively. Graft surfaces were evaluated for thrombus coverage, cell coverage, and the number of micr o-ostia. Components and cellular types in the graft wall and on the su rface were studied and characterized with H&E, histochemical, and immu nocytochemical staining. BrdU labeling was also used, to identify the areas where cells were actively proliferating. All grafts were patent. Although the degree of IVC/graft attachment varied, isolated islands of endothelial-like cells were found at the midgraft areas at each tim e period, and immunocytochemically confirmed as endothelial cells. The re were two healing patterns: (1) surface endothelialization before mi crovessel/tissue ingrowth from the perigraft areas, and (2) surface en dothelialization with full wall microvessel and tissue presence. Surfa ce endothelialization was observed before perigraft tissue ingrowth, i ndicating that fallout healing is an independent source of endothelial ization for porous grafts.