Collagen Scaffold Combined With CBD-VEGF Promotes Repair And Regeneration After Partial Lung Resection In Rats

Background and objective Lung transplantation is the only treatment for end-stage lung disease,but it faces many problems,such as primary lung transplant dysfunction,the shortage of donor organs,the low survival rate and long-term immunosuppression.It is urgent to find a new treatment to solve the regeneration problem of damaged lung tissue.With the development of tissue engineering,more and more functional biomaterials have been used in the repair and regeneration of different organs such as skin,bone,uterus,spinal cord,and myocardium and have obtained partial structural and functional recovery.This suggests it may also be promising to induce lung regeneration.However,there are few reports on the repair of lung tissue by materials,and the insufficient vascularization limits the lung tissue regeneration within the scaffold,which can lead to increased vascular permeability,pulmonary edema,alveolar prevent coagulation.VEGF is known as the most powerful angiogenic factors,and it can promote the formation of vascular endothelial cells.In addition,it has been reported that VEGF could inhibit the apoptosis of endothelial cell,which can suppress the infiltration of inflammatory cells.At the same time,studies have confirmed that VEGF has the function of promoting the migration of type II alveolar epithelial cells and transforming it into type I alveolar epithelial cells.In this studie,we used the collagen binding VEGF(CBD-VEGF)to modify the collagen materials to achieve controlled release of CBD-VEGF from the scaffold.The CBD-VEGF modified scaffold were implanted into acute partial lung resection rats to detect the repair and regeneration ability.Methods 1.An animal model of acute partial lung resection was made by surgically cutting one-half of the right lower lobe of the rat to give hemostasis and anti-infective means.2.We constructed a functional three-dimensional scaffold consisting of collagen scaffold and CBD-VEGF,which are used to promote lung regeneration in the defect site.3.SD rats were divided into 4 groups,namely normal group(normal rats),control group(injuried rats without scaffold implantation),collagen group(injuried rats with blank collagen scaffold implantation),and Collagen+CBD-VEGF group(injuried rats with CBD-VEGF and collagen implantation).(n=5).Blood gas analysis was performed at,3,5,7 days and 1 month after the surgery to observe lung function.4.Immunohistochemical staining of lung tissue at 7 days displayed inflammatory cell and alveolar epithelial cells infiltration and migration.HE staining was performed at the 1 month to evaluate the regeneration of blood vessel,bronchi and alveoli in the scaffold.Result: 1.In 3,5 and 7 days post surgery,blood gas analysis showed that PH,PO2 and SO2 in CBD-VEGF/Collagen group were higher than control and collagen group.PH was statistically different between the control group and the CBD-VEGF/Collagen group,but there was no statistical difference between the defect group and the collagen group.There was a statistically significant difference in PO2 between the control group and the CBD-VEGF/Collagen group.SO2 was statistically different between the defect group and the CBD-VEGF/Collagen group.2.At the long-term 1 month post surgery,blood gas analysis showed that PH,PO2 and SO2 in CBD-VEGF/Collagen group were higher than control and collagen group.PH,PO2,SO2 showed statistically significant difference between the control group and the CBD-VEGF/Collagen group.There was a statistically significant difference in PH between the collagen group and the control group,and there was no statistical difference between the CBD-VEGF/Collagen group and collagen group.There was statistical difference between the collagen group and the control group on PO2,and there was a statistical difference between the CBD-VEGF/Collagen group.3.HE staining showed that there was more neovascularization in the CBD-VEGF group.In the collagen material part,a large-diameter trachea was observed deep in the collagen material,Immunohistochemical staining of inflammatory cells was performed using anti-CD45 antibody 7 days after surgery.The CBD-VEGF/Collagen group showed less inflammatory cell infiltration in the border region of the graft than that of the collagen material group.4.Immunofluorescence staining of type I alveolar epithelial cells was performed 7 days after surgery with anti-AQP5 antibody.Type I alveolar epithelial cells were found in the border area of the graft,and the collagen-binding VEGF factor group had more than the single material group.Type I alveolar epithelial cells are produced.Conclusion 1.Collagen scaffolds,especially when combined with CBD-VEGF,can partially promote the recovery of blood gas PH,PO2 and SO2 in acute partial lung resection rats.2.The collagen scaffold modified with CBD-VEGF can promote the formation of new blood vessels and bronchi in acute partial lung resection rats.3.Collagen scaffold combined with CBD-VEGF can reduce the inflammatory infiltration of acute lung injury and promote the migration and activation of alveolar epithelial cells in the scaffolds.