Perigraft adventitia and intima remodeling after synthetic patch implantation in sheep carotid artery: role of apoptosis and proliferation.

Background: The mechanisms of neointima formation after synthetic vascular grafting are not clear. The aim of this study was to investigate the intima and perigraft adventitia remodeling process in terms of cell apoptosis versus proliferation after synthetic patch implantation.

Methods: Female Merino sheep were randomized equally into two groups and underwent implantion with a patch of gelatin sealed Dacron graft into the left common carotid artery. At 1 and 6 months, grafted vessels were harvested, processed, and assessed. Intimal area and lumen sizes were measured with histologic assessment of eight segments from each animal assisted with image analysis. Immunohistochemical labeling of alpha-actin and D33 desmin was performed on tissue sections of perigraft adventitia, graft matrix, and intima. Cell proliferation and cell phenotype were determined with double immunohistochemical staining with anti-proliferating cell nuclear antigen and anti-alpha-actin or antimacrophage antibodies (HAM 56) in perigraft adventitia, graft matrix, and intima. Apoptosis was detected with in situ terminal deoxynucleiotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate-fluorescence nick end labeling (TUNEL) in perigraft adventitia, graft matrix, and intima.

Results: The carotid artery lumen size at 6 months was significantly larger than at 1 month (P
Conclusion: The cell proliferation and cell phenotype change in intima and perigraft adventitia are associated with thickening of perigraft adventitia and intima at 1 month. The balance between cell proliferation and apoptosis could account in part for the reduction in intima area and perigraft adventitial cellularity at 6 months.