title: Lipopolysaccharide preconditioning enhances the efficacy of mesenchymal stem cells transplantation in a rat model of acute myocardial infarction.
abstract: BACKGROUND
  Mesenchymal stem cells (MSCs)-based regenerative therapy is currently regarded as an alternative approach to salvage the acute myocardial infarcted hearts. However, the efficiency of MSCs transplantation is limited by lower survival rate of engrafted MSCs. In previous study, we found that 1.0 microg/ml Lipopolysaccharide (LPS) could protect MSCs against apoptosis induced by oxidative stress and meanwhile enhance the proliferation of MSCs. Therefore, in the present study, we firstly preconditioned MSCs with 1.0 microg/ml LPS, then transplanted MSCs into ischemic myocardium, and observed the survival and cardiac protective capacity of MSCs in a rat model of acute myocardial infarction. Furthermore, we tried to explore the underlying mechanisms and the role of Toll-like receptor-4 (TLR4) in the signal pathway of LPS-induced cardiac protection.
  
  
  RESULTS
  Acute myocardial infarction model was developed by left anterior descending coronary artery ligation. 60 rats were divided into 4 groups randomly and given an intramyocardial injection of one of the following treatments: 30 microl PBS (control group), 3 x 10(6) wild MSCs/30 microl (wMSCs group), 3 x 10(6) LPS-preconditioned wild MSCs/30 microl (LPS-wMSCs group), or 3 x 10(6) LPS-preconditioned TLR4 gene deleted MSCs/30 microl (LPS-tMSCs group). After 3 weeks, LPS-preconditioned wild MSCs transplantation ameliorated cardiac function and reduced fibrosis of infarcted myocardium. Vascular density was markedly increased in LPS-wMSCs group compared with other three groups. Survival rate of engrafted MSCs was elevated and apoptosis of myocardium was reduced in infarcted heart. Expression of vascular endothelial growth factor (VEGF) and phospho-Akt was increased in the infarcted myocardium after transplantation of LPS-preconditioned MSCs.
  
  
  CONCLUSIONS
  LPS preconditioning enhanced survival of engrafted MSCs, stimulated expression of VEGF and activated PI3K/Akt pathway. LPS preconditioning before MSCs transplantation resulted in superior therapeutic neovascularization and recovery of cardiac function. LPS preconditioning provided a novel strategy in maximizing biologic and functional properties of MSCs.
authors.affiliation: Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, Nanjing 210029, PR China. ywyao78@sina.com.cn
authors.forename: Yongwei
authors.initials: Y
authors.lastname: Yao
authors.forename: Fumin
authors.initials: F
authors.lastname: Zhang
authors.forename: Liansheng
authors.initials: L
authors.lastname: Wang
authors.forename: Guohui
authors.initials: G
authors.lastname: Zhang
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Wang
authors.forename: Jianmei
authors.initials: J
authors.lastname: Chen
authors.forename: Xiang
authors.initials: X
authors.lastname: Gao
mesh_terms: D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects / Q000637:transplantation; D004353:Drug Evaluation, Preclinical; D005260:Female; D006085:Graft Survival; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009203:Myocardial Infarction / Q000601:surgery*; D018384:Oxidative Stress; D051057:Proto-Oncogene Proteins c-akt / Q000096:biosynthesis / Q000235:genetics; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D051197:Toll-Like Receptor 4 / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D014183:Transplantation, Heterologous; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis / Q000235:genetics
chemical_list: D008070:Lipopolysaccharides; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; C494920:Akt1 protein, rat; D051057:Proto-Oncogene Proteins c-akt
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