Experimental Study On ECM Hydrogel Delivery Of MSC To Reduce Severe Acute Pancreatitis

Severe acute pancreatitis(SAP)is a benign disease characterized by acute onset,severe disease,multiple complications,and high mortality.SAP is often accompanied by severe complications such as secondary infections around the pancreas,systemic inflammatory response syndrome(SIRS)and even multiple organ failure(MODS)during the progression of the disease.The mortality rate of patients is as high as 15%-30%.The inflammatory cascade caused by the immune imbalance of SAP is the main reason for the high mortality of patients.At present,the treatment for SAP at home and abroad is still mainly symptomatic and supportive treatment,and there is no ideal measure to reduce the mortality of patients.Therefore,it is of great significance to find a new treatment strategy that can reshape the immune balance of the body in the treatment of SAP.The development of stem cells and tissue engineering brings new opportunities for the treatment of SAP.At present,there are many reports on the research of stem cell transplantation technology in SAP treatment at home and abroad.Among them,bone marrow mesenchymal stem cells are transplanted into SAP rats to repair pancreatic injury and regenerate.Although stem cell transplantation can reduce inflammation to a certain extent and repair impaired pancreatic function,simple stem cell transplantation also has obvious limitations.For example,damaged tissue ischemia,hypoxia,and massive production of inflammatory factors,resulting in low transplant cell retention and survival rates.As a novel tool,hydrogels can be used for stem cell delivery and have received close attention from researchers in regenerative medicine.Among them,the extracellular matrix(ECM)hydrogel material is made by dissolving decellularized organ tissue scaffold materials,which can retain relatively complete extracellular matrix components,three-dimensional structure and biologically active molecules,and has good biological properties.Compatibility and low immunogenicity have attracted people’s attention.As a delivery vehicle,hydrogel has the following advantages: providing cells with growth space,promoting cell survival and adhesion,and improving the microenvironment of the injured site.It can be seen that hydrogels as a delivery vehicle for stem cells are expected to overcome the limitations of simple stem cell transplantation.At present,hydrogels combined with stem cells have been used to repair various tissue damages.For example,diabetic skin wounds,spinal cord injury,hind limb ischemic injury,cartilage defect injury,and myocardial infarction.However,there are few reports on the study of hydrogel combined with mesenchymal stem cells to treat SAP.Therefore,this study mainly explores the protective effect and mechanism of pancreatic extracellular matrix hydrogel combined with placental-derived MSCs(P-MSCs)on severe acute pancreatitis in rats.The first step of this project is to prepare pancreatic acellular matrix hydrogel.First,the fresh porcine pancreas obtained from the slaughterhouse is stirred and filtered to make the pancreatic acellular matrix,and then hematoxylin-eosin(HE)staining is used to determine the cells Whether the components are completely eluted,next,the pancreatic acellular matrix is lyophilized at low temperature,milled,sterilized and dissolved in a concentrated hydrochloric acid pepsin solution to prepare a pancreatic acellular matrix hydrogel.Finally,we performed phalloidin staining and CCK-8 detection to evaluate the effect of hydrogel on the proliferation and adhesion of P-MSCs.P-MSCs were derived from the isolation and culture of the previous research of our group,and the third to fifth generation cells were selected for this study.The hydrogels combined with P-MSCs were injected into the pancreatic tissue of SAP rats through local multi-point injections.The results showed that:(1)The hydrogels combined with P-MSCs can effectively reduce the pathological damage of the pancreas in SAP rats;(2)Hydrogels combined with P-MSCs can significantly reduce the systemic inflammatory response in SAP rats;(3)Hydrogel combined with P-MSCs can induce M2 polarization of SAP rat macrophages;(4)Hydrogel can promote P-MSCs in vivo Survive.In order to further clarify the protective mechanism of hydrogel combined with P-MSCs on SAP rats,we explored how P-MSCs regulate the polarization of macrophages from M1 to M2 from the perspective of molecular biology.Studies have reported that MSCs can inhibit the activation of STAT3 protein by secreting TSG-6 to induce macrophages to polarize to M2,thereby reducing tissue inflammatory damage.To this end,we observed the expression of key proteins in the STAT3-NF-κB signaling pathway in rat pancreatic tissue.The experimental results showed that compared with the SAP group,the P-MSCs group p-STAT3,p-P65,pIKB-The expression of α is significantly reduced.In summary,hydrogels combined with P-MSCs may inhibit the STAT3-NF-κB signaling pathway by secreting TSG-6,promote the polarization of macrophages to M2,and thereby reduce pancreatic injury and systemic inflammation in SAP rats.