MicroRNA-92a -mediated endothelial to mesenchymal transition controls vein graft neointimal lesion formation.

PURPOSE: Long-term failure of vein grafts due to neointimal hyperplasia remains an important problem in coronary artery bypass graft surgery. Endothelial to mesenchymal transition (EndMT) contributes to vein graft vascular remodeling. However, there is little study on microRNA-mediated EndMT contributions to neointimal formation in vein graft. We hypothesized that microRNA-92a (miR-92a) might play an important role in determining EndMT contributions to neointimal formation. METHODS: miR-92a and EndMT-related proteins detected by qRT-PCR and Western blot in vitro and in vivo. Adeno-associated virus 6 (AAV6) delivery gene therapy was used to inhibit neointimal formation in vivo. The intimal hyperplasia of vein grafts was measured by HE staining, the expression of EndMT-related protein in vein grafts was measured by immunofluorescence. Immunohistochemistry and luciferase assay were used to detect potential targets of miR-92a. RESULTS: The expression of miR-92a was found to be upregulated in neointimal hyperplasic lesions after vein grafting. Using cultured human umbilical vein endothelial cells (HUVECs), we show that TGF-ß1 treatment of HUVECs significantly increased miR-92a expression and induced EndMT, characterized by suppression of endothelial-specific markers (CD31 and VE-cadherin) and an increase in mesenchymal-specific markers (a-SMA and vimentin), while inhibition of miR-92a expression blunted EndMT in cultured HUVECs. Furthermore, AAV6 mediated miR-92a suppression gene therapy effectively resulted in decreased EndMT and less neointimal formation in vein grafts in vivo. We further identified that integrin alpha 5 (ITGA5) is a potential target gene involved in the development of neointima formation in these vein grafts. CONCLUSION: This data suggests that neointimal formation does not solely rely on vascular smooth muscle cell phenotypic switching but is also related to EndMT, and miR-92a-mediated EndMT is an important mechanism underlying neointimal formation in vein grafts.

Comparison of the Outcomes of Modified Artificial Chordae Technique for Mitral Regurgitation through Right Minithoracotomy or Median Sternotomy.

BACKGROUND: Right minithoracotomy (RM) has been proven to be a safe and effective approach for mitral valve surgery, but the differences of artificial chordae technique between RM and median sternotomy (MS) were seldom reported. Here, we compared the outcomes of modified artificial chordae technique for mitral regurgitation (MR) through RM or MS approaches. METHODS: One hundred and eighteen consecutive adult patients who received mitral valve repair with artificial chordae and annuloplasty for MR through RM (n = 58) or MS (n = 60) from January 2006 to January 2015 were analyzed. RESULTS: All of the selected patients underwent mitral valve repair successfully without any complication during the surgery. There was no significant difference between RM group and MS group in cardiopulmonary bypass time, aortic cross-clamp time, and early postoperative complications. However, compared with the MS group, the RM group had shorter hospital stay and faster surgical recovery. At a mean follow-up of 44.8 ± 25.0 months, the freedom from more than moderate MR was 93.9% ± 3.5% in RM group and 94.8% ± 2.9% in MS group at 3 years postoperatively. Log-rank test showed that there was no significant difference in the freedom from recurrent significant MR between the two groups (χ2 = 0.247, P = 0.619). Multivariate analysis revealed that the presence of mild MR at discharge was the independent risk factor for the recurrent significant MR. CONCLUSION: Right minithoracotomy can achieve the similar therapeutic effects with MS for the patients who received modified artificial chordae technique for treating MR.