Research On The Effect Of Material Surface Miro-Structure On Von Willebrand Factor Damage

Gastrointestinal bleeding during the use of mechanical circulatory support devices is a serious clinical complication associated with the reduction of von Willebrand Factor(VWF)function.VWF is a protein in plasma associated with coagulation.The reduction of its function is mainly manifested by the degradation of high molecular weight VWF.Researchers have conducted many studies on VWF damage caused by the use of mechanical circulatory support devices,most of which focus on VWF damage caused by mechanical factors.However,in addition to mechanical factors,VWF damage may also be affected by interface factors.In this study,experimental research,numerical simulation and other methods were used to investigate the effect of material surface micro-structure on VWF damage in flow state,considering the comprehensive effect of both mechanical factors and interface factors.Specific studies and results are as follows:(1)The effect of material surface roughness on VWF damage under shear flow condition was studied.Considering the damage of red blood cells and VWF,to minimize the damage of VWF,Ra value of material surface roughness in mechanical circulatory support devices should be less than 0.4 μm.In addition,it was found that the degradation of high molecular weight VWF was consistent with the reduction of the VWF ristocetin cofactor activity.(2)The effect of aspect ratio of material surface micro-structure on VWF damage under shear flow condition was studied.The results showed that VWF damage can be significantly reduced when the aspect ratio exceeds a certain range.In addition,shear stress is only an inducing factor in the process of VWF damage.The adhesion of VWF was the necessary prerequisite of VWF damage,thus reducing the adhesion of VWF to material surface can effectively reduce VWF damage.Therefore,in the design of material surface inside the mechanical circulatory support devices,it can be considered to add some surface microstructures of a certain aspect ratio without significantly increasing the non-physiological shear stress.(3)The effect of material surface micro-structure distribution on VWF damage under shear flow condition was studied.The results showed that with the encryption of the material surface micro-structure arrangement,the material surface tends to be hydrophobic,which is beneficial to reduce VWF damage.Therefore,in the design of material surface inside the mechanical circulatory support devices,it can be considered to add some surface microstructure with a certain distribution density to change the hydrophilicity and hydrophobicity of the surface,so as to reduce the VWF damage.The results of this study could provide an important reference for the comprehensive evaluation of VWF damage caused by both mechanical factors and interface factors.It could also provide a new solution idea for the optimization of mechanical circulatory support devices besides structural optimization.