KINETICS OF CELL-PROLIFERATION AS A FUNCTION OF VASCULAR GRAFT MATERIAL

Bioresorbable vascular grafts constructed for polyglactin 910 (PG910) and polydioxanone (PDS) and nonresorbable Dacron were interposed into the infrarenal abdominal aortas of New Zealand White rabbits. The pros thesis/tissue complexes were harvested after 2, 3, 4, 12, and 52 weeks . Seventeen, 9, and 1 h prior to sacrifice, animals received tritiated thymidine (0.5 mCi/kg/dose). All specimens were studied grossly and b y light and transmission electron microscopy. Mitotic indices (MI's) w ere determined by autoradiography for inner capsule myofibroblasts at the proximal, mid, and distal segments of each prosthesis. There were no aortic-related deaths. All grafts were patent with no aneurysmal di latation. At 4 weeks, PG910 resorption was evidenced by macrophage pha gocytosis, less so in PDS while Dacron remained intact. At 12 weeks, t he PG910 was completely resorbed while PDS resorption continued. The l atter was completely resorbed by 52 weeks. There was no significant di fference in MI's between proximal, mid, and distal regions for each gr aft type. The mitotic index paralleled the rate of prosthetic resorpti on in both PG910 and PDS groups, as high as 28.34 +/- 23.21 in the for mer 3 weeks after implantation and significantly higher at 4 weeks (7. 58 +/- 2.02 and 7.50 +/- 2.66, respectively) than at 52 weeks (0.72 +/ - 0.98 and 1.00 +/- 0.22, respectively) in both groups. The mitotic in dex in the Dacron group never surpassed 1.22 +/- 0.90. We conclude tha t higher levels of early cell proliferation in bioresorbable grafts cl osely parallel the kinetics of prosthetic resorption.