Abstract 221: A Single Nucleotide Polymorphism of p27Kip1 Associated with Vein Graft Patency Regulates Proliferation of Cells Derived from the Outer, but not the Inner, Venous Wall
Introduction: p27Kip1 is a cell-cycle inhibitor whose -838C>A single nucleotide polymorphism (SNP) accounts for ~40% of the risk of peripheral vein graft failure.
Methods: To determine SNP function, we tested growth of cells derived from explants of the outer and inner wall of veins (cleavage through medial circular muscle yields outer wall with adventitia and some media and inner wall with intima and some media).
Results: Growth of cells at passage 6 was measured over 3 days in response to 10 ng/ml PDGF-BB + 2% serum. Outer wall cells with the AA p27 SNP genotype grow slower than those with the CC genotype, but inner wall cells do not show a genotype-dependent response (Figure). Gene expression of quiescent outer and inner wall cells (5pairs) measured by microarray show that 2876 genes are differentially expressed (≥2 fold difference with P≤.05). While there is no difference in expression of traditional smooth muscle markers (smooth muscle α-actin, smooth muscle myosin heavy chain, smoothelin, SM22α, and calponin1), expression of the pericyte markers, NG2 and PDGFRβ, is significantly higher in outer wall cells (4.2 and 2.2 fold over inner wall cells; P<.02). We also found CD31 immunostaining of the endothelial cells of the vasa vasorum was restricted to the outer wall.
Conclusion: These results support the functionality of the p27Kip1-838C>A SNP in cellular proliferation, but only in outer wall cells. Pericytes of the vasa vasorum or other progenitors in the outer wall may be involved, but further studies must address the identity of precursors of the outer wall cells that are associated with graft failure.
Author Disclosures: R.D. Kenagy: Research Grant; Significant; HL30946. S. Kikuchi: None. L. Chen: Research Grant; Significant; HL30946. E.S. Wijelath: Research Grant; Significant; HL30946. M. Sobel: Research Grant; Significant; HL30946. A.W. Clowes: Research Grant; Significant; HL30946.
- © 2015 by American Heart Association, Inc.