Construction Of Patient-specific Tissue-engineered Vascular Patch For Arterial Defect Repair

Background and Objective: Congenital heart defects are the most common diseases in pediatric cardiac surgery,and many malformations need patches to repair.Currently,synthetic or biologic materials are usually used to construct patches;however,these materials have shortcomings such as antigenicity to the host and absence of growth potential in vivo.Furthermore,lack of recellularization on the surface of materials may lead to thrombosis formation and intimal hyperplasia.The aim of this study is to develop an endothelialized tissue-engineered vascular patch(TEVP)composed of patient-derived decellularized matrix scaffold and bone marrow stem cells and to evaluate its effect on arterial defects repair.Methods and Results: We constructed TEVP using decellularized extracellular matrix(ECM)scaffold produced from the excised human aorta,which was seeded with patient-derived bone marrow C D34-positive(CD34+)progenitor cells.While cellular components were removed,the decellularized ECM scaffold retained native extracellular matrix composition,including collagen,elastic fiber,fibronectin,laminin,and sulfated glycosaminoglycan(GAG).In strain-to-failure tests,the decellularized aortic ECM scaffold showed similar mechanical property compared to native aorta.Furthermore,the decellularized ECM scaffold was demonstrated to support adhesion,survival and proliferation of CD34+ progenitor cells.Interestingly,after in vitro seeding of decellularized aortic ECM scaffold for 21 days,C D34+ progenitor cells differentiated into vascular endothelial-like cells without addition of any growth factors,as confirmed by the increased expressions of endothelial marker CD31,VWF,VE-cadherin,ICAM-2 and gene CD31,VWF and e NOS concurrently with decreased expression of marker CD133 and CD34.Thus,surface endothelialization of decellularized ECM scaffold was achieved by induced endothelial differentiation o f bone marrow derived CD34+ progenitor cells without external stimuli.Proteomics analysis showed that the decellularized aortic ECM scaffold contains multiple proangiogenic components,including decorin,fibrillin,fibulin-1,galectin,tenascin-X,vitronectin,fibronectin,laminin,plectin,fibrinogen,perlecan and collagen,and only one antiangiogenic protein,namely,thrombospondin.In addition,protein array results indicated that the decellularized aortic ECM scaffold promoted CD34+ progenitor cells to secrete more cytokines which stimulate the endothelial differentiation of CD34+ progenitor cells,including angiogenin,GM-CSF,and leptin.We further demonstrated that decellularized aortic ECM scaffold induced the expression of DLL1 protein.In addition,CD31 protein level on CD34+ progenitor cells declined when γ-secretase inhibitor DAPT was used to block Notch signaling pathway.After implanted,the TEVP repaired the abdominal aorta defects in nude rats.CD31 immunofluorescence staining results showed that vascular patches were covered with a layer of endothelial cells,and HE staining indicated that many host cells infiltrated into the inside of vascular patch and arranged regularly at day 28 post inplantation.Moreover,obvious collagen hyperplasia was not observed and elast ic fibers were intact inside vascular patch.Thus,the TEVP can grow and remodel in vivo,thus becoming similar to normal artery in morphology.Conclusions: We constructed for the first time the patient-specific TEVP using patient-derived decellularized scaffold and CD34+ progenitor cells.The decellularized scaffold in vitro promoted endothelial differentiation of CD34+ progenitor cells,which may attribute to the proangiogenic components in scaffold and the paracrine cytokines from CD34+ progenitor cells.Notch signaling pathway was involved in the endothelial differentiation of CD34+ progenitor cells.The new TEVP can repair effectively the aortic defects and holds great potential for clinical use in patients with congenital heart defects.