Microvascular Endothelial Cell Seeding of Small-Diameter Dacron|2TM|0 Vascular Grafts

Abstract

One obstacle to the clinical implementation of endothelial cell seeding of vascular prostheses is the difficulty in derivation of large numbers of autologous endothelial cells from blood vessels of patients requiring vascular grafting. Capillary endothelial cells obtained from fat have been suggested as an abundant alternative to large-vessel endothelium for graft seeding. The object of this study was to evaluate the performance of 4-mm internal diameter (ID) Dacron™ Microvel grafts seeded with omentally derived microvascular endothelial cells. Six-cm lengths of the test grafts were implanted bilaterally into canine carotid arteries. One of each pair of grafts was seeded with endothelial cells (x = 8.4 × 10⁶) derived from collagenase digestion of autologous omental fat samples. The contralateral graft of each pair was nonseeded. At 5 weeks postoperatively, the grafts were harvested and evaluated. The mean patencies of both the seeded and nonseeded grafts were 89 percent. The mean thrombus-free surface area for seeded grafts was 95 ± 11 percent. This value was significantly different statistically from the mean thrombus-free surface area of nonseeded grafts, which was 43 ± 19 percent (P > 05). Histologically, midgraft regions of seeded grafts were cellular, stained positive for collagen, and were characterized by inner capsules ranging in thickness between 35–94 μm. Luminal cells were identified as endothelial by peroxidase antiperoxidase staining techniques. Midgraft regions of nonseeded grafts demonstrated thrombus accumulation, limited cellularity, and inner capsules between 59–194 μm thick. Scanning electron microscopy of seeded grafts revealed smooth luminal surfaces with tight junctions between adjacent cells; surface cells were not present on midgraft regions of nonseeded grafts. In conclusion, endothelial cells derived from omental fat successfully surfaced on Dacron™ grafts and imparted characteristics to the graft that would predict long-term graft success