Sequential studies of healing in endothelial seeded vascular prostheses: Histologic and ultrastructure characteristics of graft incorporation

Abstract

Chronological events leading to incorporation of endothelial cell seeded prosthetic vascular grafts were documented in this investigation. Forty-one adult dogs underwent thoracoabdominal bypass using double-velour Dacron grafts. Experimental grafts were preclotted with blood containing enzymatically derived endothelium immediately after derivation, or after 14 days of cultivation. Control grafts were preclotted without addition of endothelial cells. Grafts were studied grossly as well as by light, scanning electron, transmission electron, and fluorescence microscopy, 1 to 28 days postimplantation. Control graft healing proceeded from pannus and perigraft ingrowth. Experimental grafts healed from seeded cells as well. Platelets covered all grafts by Days 1 and 2. Thrombus accumulations on control grafts, first evident on Day 4, became maximal by Day 14. Seeded grafts appeared relatively thrombus free with patches of endothelial cells noted by 4 days. These cells were initially separated by gaps, often containing leukocytes. Endothelium became densely packed with cellular migration and proliferation. Subendothelial tissues were composed of fibrin and smooth muscle. Control and experimental grafts were approximately 10 and 80% endothelialized, respectively, by Day 28. Smooth muscle dominated subintimal tissue in experimental grafts. These cells initially appeared fibroblastoid. Endothelial seeding enhances both pseudointimal development and rapid graft incorporation.