Injectable collagen scaffold promotes swine myocardial infarction recovery by long-term local retention of transplanted human umbilical cord mesenchymal stem cells

Stem cell therapy is an attractive approach for recovery from myocardial infarction(MI)but faces the challenges of rapid diffusion and poor survival after transplantation.Here we developed an injectable collagen scaffold to promote the long-term retention of transplanted cells in chronic MI.Forty-five minipigs underwent left anterior descending artery(LAD)ligation and were equally divided into three groups 2 months later(collagen scaffold loading with human umbilical mesenchymal stem cell(hUMSC)group,hUMSC group,and placebo group(only phosphate-buffered saline(PBS)injection)).Immunofluorescence staining indicated that the retention of transplanted cells was promoted by the collagen scaffold.Echocardiography and cardiac magnetic resonance imaging(CMR)showed much higher left ventricular ejection fraction(LVEF)and lower infarct size percentage in the collagen/hUMSC group than in the hUMSC and placebo groups at 12 months after treatment.There were also higher densities of vWf-,α-sma-,and cTnT-positive cells in the infarct border zone in the collagen/cell group,as revealed by immunohistochemical analysis,suggesting better angiogenesis and more cardiomyocyte survival after MI.Thus,the injectable collagen scaffold was safe and effective on a large animal myocardial model,which is beneficial for constructing a favorable microenvironment for applying stem cells in clinical MI.

In vitro and in vivo analysis of the biocompatibility of two novel and injectable calcium phosphate cements

Calcium phosphate cements(CPCs)have been widely used as bone graft substitutes for many years.The aim of this study was to evaluate the biocompatibility of two novel injectable,bioactive cements:b-tricalcium phosphate(b-TCP)/CPC and chitosan microsphere/CPC in vitro and in vivo.This was accomplished by culturing mouse pre-osteoblastic cells(MC3T3-E1)on discs and pastes of CPCs.Cell growth,adhesion,proliferation and differentiation were assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and alkaline phosphatase assays as well as by scanning electron microscopy and fluorescence.The effect of CPC paste curing was also evaluated.Implantation of two materials into the muscle tissue of rabbits was also studied and evaluated by histological analysis.Cell analysis indicated good biocompatibility in vitro.The fluorescence assay suggested that the cured material discs had no obvious effect on cell growth,while the curing process did.Histological examination showed no inflammatory cell infiltration into soft tissue.These data suggest that b-TCP/CPC and chitosan microsphere/CPC composites may be promising injectable material for bone tissue engineering.