Mouse strain differential neointimal response in vein grafts and wire-injured arteries.

BACKGROUND Neointimal development is seen clinically after both vein grafting and balloon catheterization, but may not represent the same pathology under these 2 conditions. This study compared the degree of neointimal hyperplasia after vein grafting or arterial-injury grafts in 2 strains of mice: C57Bl/6 and FVB. METHODS AND RESULTS Jugular vein branches were interpositioned as grafts in the femoral artery of syngenic-matched mice, with graft harvest at 30 days. Wire-injured carotid arteries were grafted to the carotid arteries of syngenic-matched mice, with graft harvest at 14 days. Histomorphometry revealed no strain differences in vein grafts in the extent of position-dependent neointimal thickening or lumen cross-sectional area. Both strains showed significantly thicker neointima and less lumen area at the proximal graft site (vs the mid-graft; p<0.05). In contrast, a significantly greater neointimal thickness was found in the wire-injured carotid grafts of FVB mice vs those of C57Bl/6 mice (p<0.05). CONCLUSIONS Neointimal formation shows a vessel-dependent, strain-dependent difference, with greater arterial neointimal thickening in FVB mice. These data suggest that different mechanisms operate for arterial-injury- vs vein-graft-associated neointimal development and that the difference has a genetic basis.