THE EFFECT OF FLOW SHEAR-STRESS ON ENDOTHELIALIZATION OF IMPERVIOUS DACRON GRAFTS FROM CIRCULATING CELLS IN THE ARTERIAL AND VENOUS SYSTEMSOF THE SAME DOG

The purpose of this report was to study effects of shear force and hem odynamic 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 surf ace were implanted for 4 weeks during the same surgery in the descendi ng 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-wal l thickness longitudinal tissue sections were embedded in resin and st ained with hematoxylin and eosin for light microscopy, and in paraffin for immunocytochemistry studies with Factor VIII/von Willebrand facto r, smooth muscle cr-actin, collagen IV, laminin, and proliferating cel l nuclear antigen. Scanning electron microscopy and transmission elect ron microscopy studies were also performed. AgNO3 was used to determin e percentage of endothelial-like cell coverage on the flow surface. Al l grafts were patent, without hematoma or seroma. Endothelial-like cel l coverage was highest in the IVC grafts and lowest in the DTA. Shear stress and flow velocity were significantly lower in IVC grafts than D TA and AA. Proliferating cell nuclear antigen indicated extensive cell ular proliferation in the intima and in the interstices of the inner p ortion of the graft wall. The degree of fallout healing in knitted Dac ron grafts made impervious by an external coat of silicone rubber vari es inversely with the sheer terce of blood flow in these grafts.