Quality control assessment of ePTFE precoating procedure for in vitro endothelial cell seeding

Over the past two decades, in vitro autologous endothelial cell (EC) coverage of expanded polytetrafluoroethylene (ePTFE) graft has been developed and clinically applied with success in infrainguinal bypasses. Before endothelialization, the luminal surface of the graft has to be coated with a currently used fibrinolytically inhibited fibrin glue. The aim of this work is to validate the precoating of the ePTFE (4 mm ID) ringed graft with fibrin. Twenty cm-long grafts were precoated with fibrin glue (2 operators) then fixed for microscopy investigations. Grafts were sliced into 3 regions. Thickness analysis was evaluated by image processing. Three grafts have been tested for endothelialization and observed at days 3, 8. Cell-free coated ePTFE were imaged using high-frequency ultrasound modality. Whatever the examined segment an overall homogeneous covering protein is shown. Fibrin thickness after image processing is 8.5±0.25 and 4.1±0.4 μm for two operators (P<.001). We have evaluated reproducibility and inter- and intra-variability of the operator, assessed quality controls and quality assurance all along the prosthesis and finally endothelialization and subsequent behaviour under shear stress conditions.