Study Of Self-assembling Peptide Hydrogel Coatings With Immune Escape Capability

The application of biomedical materials such as implantable medical devices in clinical treatment is becoming increasingly widespread,and the problems caused by their implantation are becoming more and more prominent,such as foreign body reactions and inflammatory cell aggregation,which seriously threatens the prognostic process of surgery and even cause the loss of function of the implanted devices.The foreign body response mediated by immune cells takes place at the material-tissue interface and is dominated by the infiltration of monocytes and foreign body giant cells at the implantation site.Therefore,it is scientifically important to address the biological mechanisms of foreign body recognition by the immune system,and to specifically enhance the anti-foreign body response on the surface of implantable materials at the molecular and cellular levels,and to safeguard their biocompatibility with coating research strategies.There is a natural immune escape mechanism based on the CD47-"don’t eat me"protein in human red blood cells,platelets,cancer cells and other cells.CD47 specifically recognizes and binds to the SIRPαprotein on the surface of macrophages,thereby avoiding phagocytosis and clearance mediated by macrophages.Inspired by this,we constructed a self-assembling peptide hydrogel coating（RADA）₄-pep CD47 that mimics the immune escape function of CD47,which is formed by the editorial insertion of the active peptide segment pep CD47 of CD47into the（RADA）₄ self-assemblig peptide system.（RADA）₄ has excellent biocompatibility and editable properties and can exponentially increase the pep CD47 content on the material surface compared to conventional surface grafting techniques.In addition,functionalized（RADA）₄-pep CD47 peptide mixed with unmodified（RADA）₄ allows for controlled dosing of surface CD47-derived peptides.Self-assembling peptides based on（RADA）₄ can form stable in situ hydrogels under physiological conditions such as PBS,so that implanted devices can quickly form a hydrogel coating on the surface by simple dipping.This paper focuses on the role and effects of this（RADA）₄-pep CD47 hydrogel coating on the surface of a representative implant material,316L medical stainless steel（316L SS）.The surface potential,secondary structure,elemental composition,and microscopic morphology of（RADA）₄-pep CD47 were tested using DLS,CD,XPS,and SEM to characterize the materialistic properties of（RADA）₄-pep CD47,respectively.In vitro assays of HUVECs/HUASMCs/L929 proliferation activity and macrophage adhesion showed that（RADA）₄-pep CD47 has certain biocompatibility and anti-macrophage adhesion and phagocytosis ability.The ability of（RADA）₄-pep CD47 to resist inflammatory cell aggregation and inflammatory fiber formation in blood/subcutaneous tissues was demonstrated by examining the inflammatory cell aggregation/inflammatory fiber thickness on the sample surface through blood circulation assays/subcutaneous embedding assays.Eukaryotic RNA-Seq was established to examine the expression of DEGs in macrophages,and comparison of the KEGG database and GO database revealed that（RADA）₄-pep CD47 and bare 316L SS affect the macrophage innate immune process and macrophage cycle progression,separately.In summary,this paper synthesizes a（RADA）₄-pep CD47 hydrogel with immune escape ability and provides new theoretical and experimental support for its application as a dip coating in implantation procedures.