Smooth muscle cell proliferation at the vascular anastomotic stricture in rat aortotomy model

We recently suggested that a rat aortotomy model could be substituted for a vascular anastomotic stricture around a suture line. The aim of this study was to verify such a rat aortotomy model using proliferating cell nuclear antigen (PCNA) immunohistochemistry, which is a sensitive method for detection of proliferating cells in vascular tissue after injury.

Longitudinal aortotomy was performed in the abdominal aorta of the rat subjects. The rats were sacrificed at 1, 2, 4 and 8 weeks following aortotomy (n=20 in each group). The control rats were sacrificed without aortotomy (n=20). The percentage of the lumen occluded by intimal thickening (I/M ratio) was calculated. All tissues were stained with antibodies against proliferating cell nuclear antigen (PCNA).

Values of I/M ratio were 8.5+/-4.4%, 15.6+/-9.5%, 11.8+/-5.5%, 9.6+/-6.2% at 1, 2, 4, 8 weeks following aortotomy in the injured groups and 0.4+/-0.1% in the controls, respectively. Those values in the injured group increased significantly as compared to the controls. There were also significant differences between one week and two weeks following aortotomy. The PCNA labeling index at one week following aortotomy (21.4+/-2.7%) was significantly higher than at two weeks following aortotomy (2.8+/-1.9%). SMCs in the intima at four and eight weeks following aortotomy were completely negative for PCNA.

The experimental rat aortotomy model was determined to be useful in the investigation of intimal thickening around the suture line.