Comparison of two techniques to isolate microvascular endothelial cells from the omentum.

The purpose of the study was to compare two different techniques for isolation of omental microvascular endothelial cells (ECs). Segments of unreinforced polytetrafluorethylene (PTFE) grafts, 9 cm long and 6 mm in diameter, were implanted in 22 dogs as an aortic interposition. Fourteen grafts were seeded with a mean of 7 x 10(5) viable ECs, derived from the microvessels of the omentum: eight grafts (group A) were seeded with ECs obtained by collagenase digestion and by filtration through a pore mesh; six grafts (group B) were seeded with ECs obtained by collagenase digestion and by Percoll gradient separation. In eight grafts (group C), the ECs were not added to the preclot mixture and served as a control. Animals were sacrificed 5 weeks after surgery. The percentage of thrombus-free area was 65 +/- 22% for group A grafts and 74 +/- 15% for group B grafts (NS). The subendothelial layer was 280 +/- 60 microns thick in group A and 220 +/- 30 microns thick in group B (P less than 0.05). Seeded grafts showed a higher production of 6-keto-PGF1 alpha after addition of sodium arachidonate than control grafts. Percoll gradient separation allows isolation of a more purified suspension of ECs. Refinements in omental EC procurement are still required to minimize contamination with other types of cells.