Immunolocalization of proliferating cells in the rabbit iliac artery after balloon angioplasty.

PURPOSE Experiments were performed to characterize the location of proliferating cells in the balloon-dilated rabbit iliac artery. MATERIALS AND METHODS Balloon angioplasty was performed on the external iliac arteries in each of four rabbits. The arteries were removed 3 days later, frozen, cryosectioned, and immunostained with Ki-67, an antibody that identifies proliferating cells. The sections were then examined to determine the patterns of cell proliferation within the arterial media and the ratio of proliferating to nonproliferating cells. RESULTS Of the 31 arterial cross-sections examined, cell proliferation was circumferential in five (16%), and focal in 26 (84%). Of the 86 foci of proliferation examined within the 31 cross-sections, proliferation was localized to the inner media in 30 (35%), to the outer media in four (5%), and was transmural in 52 (60%). The internal elastica lamina (IEL) appeared normal at 22 foci (26%), but appeared stretched or torn at 64 (74%). Proliferation was usually confined to the inner media at foci having no IEL injury (18 of 22; 82%), but was most often transmural where the IEL was stretched or torn (49 of 64; 77%). The ratio of proliferating to nonproliferating cells, which averaged 0.31 ± .20, was greater ( P CONCLUSION These results suggest that angioplasty-induced cell proliferation is typically focal rather than circumferential and is associated with stretching or tearing of the IEL.