Inducible expression of basic transcription element-binding protein 2 in proliferating smooth muscle cells at the vascular anastomotic stricture

Objective: The proliferation of vascular smooth muscle cells surrounding a suture line is an important factor in the development of anastomotic strict ure that is frequently seen after coronary artery bypass grafting. The aim of this study was to investigate the time course of intimal thickening and to examine the expression of the molecular marker of smooth muscle cell act ivation surrounding the suture line. Methods: Longitudinal aortotomy was per-formed in the abdominal aorta of ra ts. The rats were put to death 1, 2, 4, and 8 weeks after aortotomy, and th e percentage of the lumen occluded by intimal thickening was calculated. Al l tissues were stained with antibodies against basic transcription element- binding protein 2, human cyclin-dependent kinase (cdk4), and Sp1 for immuno histochemistry. Basic transcription element-binding protein 2 is a transcri ption factor that is involved in phenotypic modulation of vascular smooth m uscle cells. Cdk4 represents a marker for G(1) phase of the cell cycle. Spl is a transcription factor known to be expressed in a variety of tissues. B asic transcription element-binding protein 2 messenger RNA expression was c onfirmed by means of reverse transcriptase-polymerase chain reaction, Results: We noted significant thickening of the intimal layer I week after aortotomy, Immunohistochemistry demonstrated that smooth muscle cells in th e neointima were strongly positive for basic transcription element-binding protein 2 and human cyclin-dependent kinase 4, which peaked 2 weeks after a ortotomy. Basic transcription element-binding protein 2 expression was clos ely associated with human cyclin-dependent kinase 4 expression in the neoin tima, although Spl was not. Basic transcription element-binding protein 2 m essenger RNA levels were significantly up-regulated early after aortotomy. Conclusion: The experimental rat aortotomy model is useful to investigate t he proliferation of vascular smooth muscle cells around the suture line. Mo reover, our results suggest the possible role of basic transcription elemen t-binding protein 2 in the development of vascular anastomotic strictures.