EFFECT OF PROLONGED PULSATILE SHEAR-STRESS IN-VITRO ON ENDOTHELIAL-CELL SEEDED PTFE AND COMPLIANT POLYURETHANE VASCULAR GRAFTS

Objectives: Compliance mismatch between graft and native artery, and f ailure of the graft to develop an endothelial lining are the two main factors in graft failure. The objective of this study was to assess a new compliant graft for effective cell attachment and cell retention a t physiological levels of pulsatile shear stress over a 6-hour period of physiological pulsatile flow. Design: Laboratory haemodynamic study . Materials and Methods: Human umbilical vein endothelial cells labell ed with In-111-oxine were seeded on compliant polyurethane (CPU) and p olytetrafluoroethylene (PTFE) vascular grafts. These were then exposed to varying shear stresses of up to 23.8 +/- 0.6 dyn/cm(2) using a pul satile flow model. Dynamic scintigraphy images were acquired using a g amma camera linked to an on-line computer during 6 h of perfusion and data presented as mean+/-standard error of mean. Results: Mean seeding efficiencies were significantly different at 4,316+/-505 and 825+/-50 4 CPM/cm(2) on the CPU and PTFE grafts, respectively (p = 0.018). The flow experiment showed a higher percentage of cells retained on the CP U graft after exposure to shear stress caused by pulsatile flow compar ed to PTFE with respect to time. After 6 h pulsatile perfusion there w as a significantly higher proportion of initial cells attached to CPU graft compared to PTFE graft (73+/-8% vs 42+/-8%, p=0.018). The areas under the time activity curves over the 6-hour period were 280+/-26.4 for CPU and 176.0+/-30.0 for PTFE, confirming a significant greater fe tal cell loss from PTFE compared with CPU grafts (51+/-7.0% vs 23+/-8. 3%, p=0.018, Wilcoxon matched-pairs signed-ranks test). Conclusions: T his flow model provides an effective method of assessing cell retentio n on graft materials under physiological conditions over a 6-hour peri od; CPU combines both excellent compliance and endothelial cell attach ment rates after 6 h exposure to shear stress.