Effect Of Magnesium-based Materials For Vascular Stents On Vascular Cells Based On Microfluidic Chips

Stent implantation is currently the main way to treat severe vascular stenosis caused by atherosclerosis,and bioabsorbable vascular stents（BVS）have become an important research direction for new vascular stents.Magnesium and magnesium alloy materials have good biocompatibility and mechanical support properties,and can be degraded in the human body,so they have good application prospects in the field of bioabsorbable vascular stents.Normal vascular cells are in a blood flow environment,and conventional cytological evaluation of vascular scaffold materials is generally carried out in cell culture plates,which cannot truly simulate the interaction between materials and vascular cells under blood flow.Microfluidic chip technology is an emerging experimental platform with high sensitivity,flexible integration,and low sample consumption.Because the chip channel size is similar to the cell size,it is widely used in biomedical research.Through software simulation and design,we prepared a 4-channel microfluidic chip for the co-culture of vascular cells and magnesium-based material extract to evaluate the effect of magnesium-based materials for vascular stents on vascular cells.Using cell complete medium as the extraction medium,four kinds of magnesium-based material extracts,pure Mg,AZ31,WE43 and Mg-Zn-Y-Nd,were prepared according to ISO10993-5 standard,and the Mg²⁺concentration and p H of in each material were determined.The results showed that when the complete medium of vascular endothelial cells（ECs）was used as the leaching medium,the corrosion resistance of the four magnesium-based materials was AZ31>WE43>Mg-Zn-Y-Nd>Mg,When the complete medium of vascular smooth muscle cells（VSMCs）was used as the extraction medium,the corrosion resistance of the material was AZ31>Mg>Mg-Zn-Y-Nd>WE43.In addition,we successfully extracted primary VSMCs from human umbilical cord by tissue adherence method.The results of cell viability and immunofluorescence assay showed that the primary VSMCs we extracted had excellent cell viability and expressed high levels of contractile proteinα-SMA,indicating that the extracted VSMCs are contractile phenotype.Three co-culture modes were set up in the experiment:co-culture of vascular cells and magnesium-based material extraction solution in the orifice plate,static co-culture in the microchip channel,and dynamic co-culture in the microchip channel to study the effect of magnesium-based materials on vascular cells.The results of the co-culture experiment in the well plate showed that the extracts of the four magnesium-based material low concentration groups（12.5%,25%,50%）significantly promoted cell proliferation on both ECs and VSMCs two kinds of vascular cells,and the high concentration group（100%）inhibits cell growth.The apoptosis behavior of the two kinds of vascular cells was dose-dependent relationship with the concentration of the extract.The rare earth elements in the WE43 and Mg-Zn-Y-Nd extracts attenuated the effect of the extract on the apoptosis of VSMCs cells in the 50%and 100%concentration groups.Changing the culture environment could affect the apoptosis behavior of the cells,but has no significant effect on the expression of the contractile proteinα-SMA in VSMCs.The expression level of the marker proteinα-SMA in VSMCs has a dose-dependent relationship with the content of Mg²⁺in the culture medium.When the culture medium is in a flowing state,the cell growth was promoted,which reduced the expression level of contractile proteinα-SMA in VSMCs,and transformed the contractile phenotype VSMCs into synthetic phenotype.In conclusion,this paper provides a new idea for the cytological evaluation of vascular scaffold materials by setting different co-culture modes,especially the dynamic co-culture mode of microfluidic chip.