Dedicator of cytokinesis 2 silencing therapy inhibits neointima formation and improves blood flow in rat vein grafts.

OBJECTIVE: The high rate of vein graft failure due to neointimal hyperplasia is a major challenge for cardiovascular surgery. Finding novel approaches to prevent neointimal hyperplasia is important. Thus, the purpose of this study was to investigate whether dedicator of cytokinesis 2 (DOCK2) plays a role in the development of neointima formation in the vein grafts. METHODS AND RESULTS: We found that DOCK2 levels were significantly elevated in the vein grafts following grafting surgery. In addition, overexpression of DOCK2 promoted venous smooth muscle cell (SMC) proliferation and migration. Conversely, knocking-down endogenous DOCK2 expression in venous SMCs inhibited SMC proliferation and migration. Consistent with this, knocking-down DOCK2 expression in the grafted veins significantly reduced neointimal formation compared with the controls 28 days after vein transplantation. Moreover, DOCK2 silencing treatment improved hemodynamics in the vein grafts. Mechanistically, knockdown of DOCK2 significantly alleviated the vein graft-induced down regulation of SMC contractile protein expression and impeded the vein graft-induction of both Cyclin D1 and PCNA expression. In particular, to ensure high efficiency when transferring the DOCK2 short hairpin RNA (shDOCK2) into the grafted veins, a 30% poloxamer F-127 gel incorporated with 0.25% trypsin was smeared around the vein grafts to increase the adenovirus contact time and penetration. CONCLUSIONS: DOCK2 silencing gene therapy effectively attenuates neointimal hyperplasia in vein grafts. Knock-down of DOCK2 would be a potential therapeutic approach for the treatment of vein graft failure.

MicroRNA-146a sponge therapy suppresses neointimal formation in rat vein grafts.

The long-term failure of vein grafts due to neointimal hyperplasia remains a difficult problem in cardiovascular surgery. Exploring novel approaches to prevent neointimal hyperplasia is important. MicroRNA-146a (miR-146a) plays an essential role in promoting vascular smooth muscle cell (VSMC) proliferation. Thus, the aim of the present study is to investigate whether adenovirus-mediated miR-146a sponge (Ad-miR-146a-SP) gene therapy could attenuate neointimal formation in rat vein grafts. (Ad-miR-146a-SP) was constructed to transfect cultured VSMCs and grafted veins. To improve the efficiency of transferring the miR-146a sponge gene into the grafted veins, 20% poloxamer F-127 gel incorporated with 0.25% trypsin was used to increase adenovirus contact time and penetration. miR-146a-SP transduction significantly reduced the expression of miR-146a both in cultured VSMCs and vein grafts. miR-146a sponge markedly attenuated VSMC proliferation and migration. Consistent with this, miR-146a sponge gene therapy significantly attenuated neointimal formation and also improved blood flow in the vein grafts. Mechanistically, we identified the Krüppel-like factor 4(KLF4) as a potential downstream target gene of miR-146a in vein grafts. Our data show that miR-146a sponge gene therapy could effectively reduce miR-146a activity and attenuate neointimal formation in vein grafts, suggesting its potential therapeutic application for prevention of vein graft failure. © 2018 IUBMB Life, 71(1):125-133, 2019.

MicroRNA-365 promotes the contractile phenotype of venous smooth muscle cells and inhibits neointimal formation in rat vein grafts.

The high rate of autologous vein graft failure caused by neointimal hyperplasia remains an unresolved issue in the field of cardiovascular surgery; therefore, it is important to explore new methods for protecting against neointimal hyperplasia. MicroRNA-365 has been reported to inhibit the proliferation of vascular smooth muscle cells (SMCs). This study aimed to test whether adenovirus-mediated miR-365 was able to attenuate neointimal formation in rat vein grafts. We found that miR-365 expression was substantially reduced in vein grafts following engraftment. In vitro, overexpression of miR-365 promoted smooth muscle-specific gene expression and inhibited venous SMC proliferation and migration. Consistent with this, overexpression of miR-365 in a rat vein graft model significantly reduced grafting-induced neointimal formation and effectively improved the hemodynamics of the vein grafts. Mechanistically, we identified that cyclin D1 as a potential downstream target of miR-365 in vein grafts. Specially, to increase the efficiency of miR-365 gene transfection, a 30% poloxamer F-127 gel containing 0.25% trypsin was mixed with adenovirus and spread around the vein grafts to increase the adenovirus contact time and penetration. We showed that adenovirus-mediated miR-365 attenuated venous SMC proliferation and migration in vitro and effectively inhibited neointimal formation in rat vein grafts. Restoring expression of miR-365 is a potential therapeutic approach for the treatment of vein graft failure. © 2019 IUBMB Life, 2019.