Pattern of arrangement of smooth muscle cells in neointimae of synthetic vascular prostheses.

Neointimae of fabric vascular prostheses of three types (crimped and knitted [A], stretchable [B], and expansile [C]) were examined under both light and electron microscopes from 1 to 1,240 days after implantation in the thoracic aorta of 161 dogs. With all types of prostheses, a very uniform arrangement of smooth muscle cells was observed beneath the endothelial cells. In the crimped and knitted prostheses (A), the smooth muscle cells in the neointima showed a regular arrangement perpendicular to the direction of the bloodstream at each inner ridge of the crimp. In the stretchable prostheses (B), which can stretch only longitudinally, the long axes of the smooth muscle cells oriented in rows parallel to the bloodstream. In the expensive prostheses (C), which can expand only circumferentially, the smooth muscle cells were perpendicular to the bloodstream. These observations suggest that the arrangement of the smooth muscle cells in neointima is largely governed by the tension to which they are subjected.