Thermal sensitivity of endothelial cells on synthetic vascular graft material

The goal is to identify thermal exposures capable of reducing or eliminating cell survival on expanded polytetrafluoroethylene (ePTFE), in an effort to develop a mild hyperthermia treatment of neointimal hyperplasia in ePTFE vascular grafts.

Viable and dead bovine aortic endothelial cells were quantified following different thermal exposure conditions: cells on collagen-coated ePTFE sheets or tissue culture polystyrene dishes were heated at 42° and 45°C to determine their thermal sensitivity on different surfaces, and cells cultured on collagen-coated ePTFE sheets were heated at 43-50°C for various durations, followed by incubation at 37°C for 0 and 20 h, respectively. Significant cell death was set to be 50%. Two types of cell death, apoptosis and necrosis, were distinguished by cell morphology and membrane integrity assessments.

The attachment and survival of cells on ePTFE sheets were more sensitive to inhibition by mild heating than those on tissue culture dishes. Exposure to 45°C for 90 min and 50°C for 30 min caused significant necrotic cell death on ePTFE (65% and 75%, respectively). A 37°C/20-h incubation following 30-min exposures at 47° and 50°C increased total cell death (necrosis + apoptosis) from 20% to 50% and 75% to 100%, respectively.

Cells grown on ePTFE were more susceptible to mild hyperthermia-induced death, compared to those on tissue culture dishes. Significant cell death on ePTFE mainly via apoptosis can be achieved by optimising temperature and duration of exposure.