The effect of flow shear stress on endothelialization of impervious dacron grafts from circulating cells in the arterial and venous systems of the same dog

Abstract

The purpose of this report was to study effects of shear force and hemodynamic conditions that influence fallout healing in the arterial and venous systems of the same dog. Knitted Dacron grafts made impervious by a 1.5 mm thick coat of silicone rubber bonded to the external surface were implanted for 4 weeks during the same surgery in the descending thoracic aorta (DTA), abdominal aorta (AA) and inferior vena cava (IVC) of each of five dogs. Flow rates were measured during surgery and shear stresses calculated with the Hagen-Poiseuille formula. Full-wall thickness longitudinal tissue sections were embedded in resin and stained with hematoxylin and eosin for light microscopy, and in paraffin for immunocytochemistry studies with Factor VIII/von Willebrand factor, smooth muscle α-actin, collagen IV, laminin, and proliferating cell nuclear antigen. Scanning electron microscopy and transmission electron microscopy studies were also performed. AgN0₃ was used to determine percentage of endothelial-like cell coverage on the flow surface. All grafts were patent, without hematoma or seroma. Endothelial-like cell coverage was highest in the IVC grafts and lowest in the DTA. Shear stress and flow velocity were significantly lower in IVC grafts than DTA and AA. Proliferating cell nuclear antigen indicated extensive cellular proliferation in the intima and in the interstices of the inner portion of the graft wall. The degree of fallout healing in knitted Dacron grafts made impervious by an external coat of silicone rubber varies inversely with the sheer force of blood flow in these grafts.