The Mechanism Of Late Stent Thrombosis In Coronary Drug-eluting Stents And The Intervention Effect Of VEGF

Objective: To study the formation mechanisms of late stent thrombosis in coronarydrug-eluting stents (DES), and the possible interventional mechanisms of VEGF inprevention delayed thrombosis.Methods: The primary human umbilical vein endothelial cells and the SD rat thoracic aorticsmooth muscle cells in logarithmic growth phase were divided into the control group (C)、low concentration of paclitaxel group (Z1)、 high concentration of paclitaxel group (Z2)、low concentration of VEGF+low concentration of paclitaxel group(V1+Z1)、highconcentration of VEGF+low concentration of paclitaxel group (V2+Z1)、 lowconcentration of rapamycin group (R1)、 high concentration of rapamycin group (R2)、 lowconcentration of VEGF+low concentration of rapamycin group (V1+R1)、 highconcentration of VEGF+low concentration of rapamycin group (V2+R1). The VEC andVSMC proliferation were observed by MTT in each group; The supernatant NO wasdetected by chemical method in each VEC group; The PGI2metabolite6-keto-PGF1a, ET-1, TXA2metabolite TXB2, t-PA and PAI-1concentration were detected by ELISA in thesupernatant of each VEC group; The VEC and VSMC apoptosis were observed by flowcytometry in each group; The protein expression of the VEC and VSMC apoptosis-relatedBcl-2and Apo-1/Fas genes were observed using Western blotting in each group.Results: Compared with the control group，the VEC and VSMC proliferation was inhibitedin paclitaxel and rapamycin group(P <0.05), the VEGF group can antagonize these effects inendothelial cell group (P <0.05),but it is not obvious in smooth muscle cell group(P>0.05),There is also not statistically significant difference between the two VEGF groups (P>0.05). By the chemical and ELISA methods detection， the VEC secretion ofNO,6-keto-PGF1a and PAI-1are all inhibited in low concentration and high concentrationof paclitaxel and rapamycin groups (P <0.05), and the VEGF group can antagonize theseeffects, increased the VEC secretion of NO,6-keto-PGF1a and PAI-1(P <0.05); Lowconcentration and high concentration of paclitaxel and rapamycin group can promote theVEC secretion of t-PA, ET-1, TXB2(P <0.05), the addition of low concentration and highconcentration VEGF groups can reduce the VEC secretion of t-PA, ET-1(P <0.05), theVEGF group with a high concentration can also reduce the VEC secretion of TXB2(P<0.05), Compared with the not adding VEGF group, the low concentration VEGF groupsecretion was no significant difference (P>0.05). By the Flow cytometry detection, TheVEC and VSMC apoptosis rate was increased in paclitaxel and rapamycin groups, VEGFcan antagonize these effects on endothelial cells (P <0.05), but there is no significantdifference in smooth muscle cell group(P>0.05). Meanwhile, Western blot show thatpaclitaxel and rapamycin can make the protein expression of the VEC and VSMCapoptosis-related Bcl-2gene decrease and the protein expression of the VEC and VSMCapoptosis-related Apo-1/Fas gene increase (P <0.05), the VEGF group can antagonized theseeffects in VEC group (P <0.05), but has no effect in VSMC group (P>0.05). Conclusion: The paclitaxel and rapamycin can inhibit VEC and VSMC proliferation, affectthe VEC and VSMC secretion, induce the VEC and VSMC apoptosis, make the proteinexpression of the apoptosis-related Bcl-2gene decrease and Apo-1/Fas gene increase, VEGFcan antagonize the effect of paclitaxel and rapamycin in VEC group, but has no effect inVSMC group. Therefore, VEGF can protect the endothelial cell damage from rapamycin andpaclitaxel-eluting stents, promote the repair of the VEC，balance the secretion of theendothelial cells, promote the functions of the VEC recovery. This is promising that VEGFprevent the DES thrombosis and reduce the restenosis rate; It provide new hope for thedevelopment of new composite DES and further reduce patients taking dual antiplatelet time,reduce adverse drug reactions and the huge economic burden.