Study On The Interaction Between VSMC And Vascular Stent Materials

Vascular diseases like antherosclerosis are clinically treated by interventional therapy and vascular stent implantation with varied metals serving as the main stent materials owning to good mechanical property.Stent implantation and degradation thereof caused vascular mircroenvironment change like pH,osmotic pressure and ionic concentration,impacting the biological behaviours of vascular cells,which on the contrary influenced the local vascular microenvironment and degradation of material itself.As vascular smooth muscle cell（VSMC）played a significant role in the emergence and development of the leftover of stent implantation.This study herein mainly focused on the interaction between VSMC and four main metallic stent materials.First of all,contractile SMCs were directly and indirectly co-cultured with pre-treated pure Mg&Zn respectively.Material characterizations like SEM,XRD,degradation rate and mass weighing,and ionic concentration and pH in co-culture microenvironment were then processed to observe the influence of VSMC on Mg&Zn degradation.Results illustrated that SMC adhesion can resist metal degradation especially Mg via retaining corrosion products without change of corrosion type and deposit components.VSMC in co-culture microenvironment decreased pH,and released Mg²⁺and Ca²⁺via apoptosis.Secondly,contractile VSMC,cocultured with biodegradable Mg and Zn respectively,lost fusiform shape and proliferation was prohibited,wherein Zn had weaker influence than Mg.However,VSMC cocultured with non-biodegradable Ti and 316L-SS,maintained normal morphology and growth state.RT-PCR results showed that contractile VSMC became more inflammatory expression under cocultured condition with four materials.Biodegradable materials obviously restrained contractile gene expression and induced inflammatory ones;non-biodegradable materials had weak inhibition on contractile expression but also caused inflammatory gene expression at late culture stage.Finally,cholesterol was adopted to induce contractile VSMCs into inflammatory type,to observe the influence of Mg and Zn extracts on phenotype induction and reservation of inflammatory VSMC.Results showed that extracts inhibited both.RE-PCR,western blot and ICC illustrated that both extracts can upregulate contractile gene ofα-Sma and Myh11,downregulate inflammatory gene of CD68 and CD20.Either displacing extracts by single ionic solution or using Mg²⁺channel inhibitor,further confirmed that Mg²⁺(and Zn²⁺)can partially mediate the inhibition of extracts on VSMC inflammatory phenotype.Research results above in this study indicated that VSMC and vascular metallic stent material can interrelate and interact on each other.