Modulation of myofibroblast proliferation by vascular prosthesis biomechanics

Cyclic deformation in vitro modulates smooth muscle cell proliferation. Different degrees of cell deformation occur in vivo on grafts of different compliance. This study evaluates the influence of prosthetic biomechanics on cell proliferation. Two types of composite 80% bioresorbable PG910/20% polypropylene (PP) aortic grafts differing only in the elasticity of the PP were implanted into rabbits. After PG910 resorption, prosthetic biomechanics were determined by PP (% elongation: Group 1, 101 +/- 6 versus Group 2, 63 +/- 4). Killing was performed at 1, 2, 3, and 6 months, and patency, dynamic compliance, mitotic index (MI), and inner capsule thickness (ICT) were determined. Initially all parameters were identical. After PG910 resorption (1-2 months), significant differences were seen. At late analysis, Group 1 MI was significantly greater than Group 2 (3 months: 4.67 +/- 2.5 versus 3.11 +/- 2.5 [p < 0.02]; 6 months: 4.11 +/- 2.3 versus 2.67 +/- 0.9 [p < 0.005]). Inner capsule thickness in Group 1 was also significantly greater than Group 2 (3 months: 219 +/- 20 versus 129 +/- 40 [p < 0.05]; 6 months: 220 +/- 50 versus 130 +/- 40 [p < 0.05]). Dynamic compliance differed at 2 months (p = 0.057). Patency was worse in Group 1 (p = NS). In vivo cellular proliferative activity is directly related to mural cyclic deformation induced by altered biomechanical graft characteristics.