LONG-TERM RESULTS OF TISSUE-DEVELOPMENT AND CELL-DIFFERENTIATION ON DACRON PROSTHESES SEEDED WITH MICROVASCULAR CELLS IN DOGS

Purpose: The purpose of this study was to investigate in vivo the long -term development, differentiation, and proliferation of the subendoth elial tissue on Dacron prostheses seeded with microvascular cells (MVC ). Methods: Autologous MVC from omental adipose tissue were seeded on 4 mm Dacron prostheses and the prostheses interposed in the carotid ar teries of mongrel dogs for 5, 13, and 26 weeks. Results: Light and ele ctron microscopic evaluation of patent seeded prostheses demonstrated an almost complete monolayer of endothelial cells and well-organized s ubendothelial tissue, whereas patent control prostheses were mainly co vered by red and white thrombi, which were partially replaced by organ ized tissue with increased implantation time. The measurements of the thickness of the luminal cell layer in seeded and control grafts showe d no statistically significant increase between 5 and 26 weeks of impl antation. The subendothelial tissue of seeded prostheses demonstrated a time-dependent maturation of highly synthesizing myofibroblasts embe dded in a collagen matrix to cells with features of smooth muscle cell s located in a collagen-elastin matrix. In control grafts examined aft er 26 weeks the spontaneous endothelialization was accompanied by a de layed or incomplete maturation of subendothelial tissue. Conclusions: Our study indicates that MVC seeded onto Dacron prostheses are able to generate a vascular wall that does not continue to proliferate after prolonged implantation and that increasingly resembles the wall of a n ormal artery in cell differentiation and intercellular matrix.