title: Multimodal in vivo imaging reveals limited allograft survival, intrapulmonary cell trapping and minimal evidence for ischemia-directed BMSC homing.
abstract: BACKGROUND
  Despite positive reports on the efficacy of stem cell therapy for the treatment of cardiovascular disease, the nature of stem cell homing to ischemic tissues remains elusive.
  
  
  RESULTS
  We used a mouse model of peripheral tissue ischemia to study the survival and homing capacity of dual reporter gene (eGFP/Luciferase) expressing bone marrow-derived stromal cells (BMSC). Cell homing and survival were studied in the presence and absence of ciclosporin A (CsA) immunosuppression using bioluminescence imaging (BLI) together with confocal endomicroscopy. Different injection strategies were applied: central venous (CV), intra-arterial (IA) and intramuscular (IM). BLI and confocal endomicroscopy evidenced complete rejection of the IM injected allogeneic BMSC transplant within 5 to 10 days. Immunosuppression with CsA could only marginally prolong graft survival. IM injected BMSC did not migrate to the site of the arterial ligation. CV injection of BMSC resulted in massive pulmonary infarction, leading to respiratory failure and death. Intrapulmonary cell trapping was evidenced by confocal endomicroscopy, BLI and fluorescence microscopy. IA injection of BMSC proved to be a feasible and safe strategy to bypass the lung circulation. During the follow-up period, neither BLI nor confocal endomicroscopy revealed any convincing ischemia-directed homing of BMSC.
  
  
  CONCLUSIONS
  BLI and confocal endomicroscopy are complementary imaging techniques for studying the in vivo biology of dual reporter gene-expressing BMSC. Allogeneic BMSC survival is limited in an immunocompetent host and cannot be preserved by CsA immunosuppression alone. We did not find substantial evidence for ischemia-directed BMSC homing and caution against CV injection of BMSC, which can lead to massive pulmonary infarction.
authors.affiliation: Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium. berteveraert@me.com
authors.forename: Bert R
authors.initials: BR
authors.lastname: Everaert
authors.forename: Irene
authors.initials: I
authors.lastname: Bergwerf
authors.forename: Nathalie
authors.initials: N
authors.lastname: De Vocht
authors.forename: Peter
authors.initials: P
authors.lastname: Ponsaerts
authors.forename: Annemie
authors.initials: A
authors.lastname: Van Der Linden
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Timmermans
authors.forename: Christiaan J
authors.initials: CJ
authors.lastname: Vrints
mesh_terms: D000818:Animals; D016572:Cyclosporine / Q000494:pharmacology; D004195:Disease Models, Animal; D017930:Genes, Reporter; D006085:Graft Survival / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007511:Ischemia / Q000628:therapy; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008163:Luminescent Measurements; D008297:Male; D045164:Mesenchymal Stem Cell Transplantation; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D014184:Transplantation, Homologous
chemical_list: C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D016572:Cyclosporine; D008156:Luciferases