Preliminary Study On Vascularization Of Polydopamine-modified Porcine Acellular Dermal Matrix Loaded With AFGF

BackgroundRapid and good vascularization of implantable skin defect repair materials is a major challenge in the research and development of tissue engineering materials for skin repair.The main way of vascularization of implantable wound repair materials is angiogenesis,that is,the original blood vessels of the margin and base grow into bioactive materials through budding or non-budding.Porcine acellular dermal matrix has been widely used as tissue engineering grafts in the reconstruction of soft tissue defects.However,lack of adequate blood supply is one of the main reasons for poor graft survival and poor healing effect.Acid fibroblast growth factor(aFGF)promotes wound angiogenesis by stimulating endothelial cell migration,proliferation,budding,and canalization.Polydopamine(pDA)secreted by mussels has low cytotoxicity,good biocompatibility and improved adhesion of biomaterials.In this study,we modified porcine acellular dermal matrix(pDA-PADM)with polydopamine to increase the role of aFGF as a potential engineered tissue vascularization system to promote angiogenesis and thereby improve the survival rate of porcine acellular dermal matrix grafts.Materials and Methods1.Preparation and characterization of Porcine Decocellular Dermal Matrix(PADM).PADM was prepared by Hypertonic salt-Alkali method and the morphological characteristics of PADM was further evaluated by H&E staining,masson staining and scanning electron microscopy.2.Preparation and Characterization of Polydopamine(pDA)-Modified Porcine Acellular Dermal Matrix(PADM).Polydopamine(pDA)was added to PADM for modification,and pDA-PADM porous scaffold was prepared by freeze-drying method.The pDA-PADM of different modification timewas evaluated from the appearance,surface,morphology,and proliferation toxicity to cells.And then we evaluated pDA with different modification times of PADM for cell proliferation and toxicity,and selected the pDA-PADM with the best performance.3.The effectiveness of Polydopamine-modified porcine extracellular dermal matrix(pDA-PADM)on loading with acid fibroblast growth factor(aFGF).The adhesion and drug-loading properties of the pDA-PADM to aFGF were evaluated by testing growth factor release experiments.4.In vitro biological evaluation of human umbilical vein endothelial cells(HUVECs)of optimized pDA-PADM after adhesion to aFGF.pDA-PADM loaded with aFGF had ideal biological functions,promoting proliferation and migration of endothelial cells,and its sustained-release aFGF could further promote vascular endothelial cell(HUVEC)tubule formation,adhesion,proliferation and migration(P<0.05).5.The capacity of optimized pDA-PADM adhesion to aFGF on enhanced vascularization and compatibility after subcutaneous implantation.The materials of pDA-PADM-FGF were subcutaneously implanted into the backs of the SD rats,with pDA-PADM-FGF group,pDA-PADM group,PADM group and PADM-FGF group established.Furthermore,the effect of vascularization of FGF-pDA-PADM after transplantation at 2,4,8,12,and 18 weeks and its in-vivo compatibility were evaluated.Results1.Preparation and characterization of Porcine Decocellular Dermal Matrix(PADM).The acellular dermal matrix(PADM)material of Albino Tibetan pig was successfully prepared by simple salt-alkali method.It mainly retains collagen and other beneficial extracellular matrix components,and presents a loose and porous network structure.2.Preparation and Characterization of Polydopamine(pDA)-Modified Porcine Acellular Dermal Matrix(PADM).PDA surface modified PADM material was successfully prepared.The surface morphology of pDA-PADM was the same as that of PADM,showing loose porous network structure and thickness of about 2mm.pDA-PADM was saturated after 12 hours of modification,and the modified 12h pDA-PADM had good adhesion and high proliferation promotion performance,and subsequent experiments proved that it had good biocompatibility and low cytotoxicity.3.The effectiveness of Polydopamine-modified porcine extracellular dermal matrix(pDA-PADM)on loading with acid fibroblast growth factor(aFGF).The pDA-PADM material successfully loaded aFGF and was able to release aFGF within a certain period of time,which indicated that it met the basic requirements as a functional material for soft tissue repair and regeneration.4.In vitro biological evaluation of human umbilical vein endothelial cells(HUVECs)of optimized pDA-PADM after adhesion to aFGF.From in vitro assays,pDA-PADM material loaded with aFGF has an ideal biological function that stimulates the proliferation and adhesion of endothelial cells,as well as promoting pericyte proliferation and migration.5.The capacity of optimized pDA-PADM adhesion to aFGF on enhanced vascularization and compatibility after subcutaneous implantation.In the experiment of subcutaneous implantation in rats,we confirmed that the composite scaffold pDA-PADM has excellent biocompatibility in vivo.Additionally,after optimized pDA-PADM loading aFGF,it can guide the migration and adhesion of skin-related cells in vivo,and promote the vascularization of tissues in vivo.ConclusionThis study preliminarily prepared a novel acellular dermal matrix material and constructed a pDA-modified composite material that can effectively adhere to more a-FGF and achieve a durable growth factor release time.This complex biomaterial promotes angiogenesis in both in vitro cell and in vivo animal experiments,which may play an important role in the vascularization of engineered vascular grafts in vivo.