title: Intramyocardial transplantation and tracking of human mesenchymal stem cells in a novel intra-uterine pre-immune fetal sheep myocardial infarction model: a proof of concept study.
abstract: Although stem-cell therapies have been suggested for cardiac-regeneration after myocardial-infarction (MI), key-questions regarding the in-vivo cell-fate remain unknown. While most available animal-models require immunosuppressive-therapy when applying human cells, the fetal-sheep being pre-immune until day 75 of gestation has been proposed for the in-vivo tracking of human cells after intra-peritoneal transplantation. We introduce a novel intra-uterine myocardial-infarction model to track human mesenchymal stem cells after direct intra-myocardial transplantation into the pre-immune fetal-sheep. Thirteen fetal-sheep (gestation age: 70-75 days) were included. Ten animals either received an intra-uterine induction of MI only (n = 4) or MI+intra-myocardial injection (IMI;n = 6) using micron-sized, iron-oxide (MPIO) labeled human mesenchymal stem cells either derived from the adipose-tissue (ATMSCs;n = 3) or the bone-marrow (BMMSCs;n = 3). Three animals received an intra-peritoneal injection (IPI;n = 3; ATMSCs;n = 2/BMMSCs;n = 1). All procedures were performed successfully and follow-up was 7-9 days. To assess human cell-fate, multimodal cell-tracking was performed via MRI and/or Micro-CT, Flow-Cytometry, PCR and immunohistochemistry. After IMI, MRI displayed an estimated amount of 1×10(5)-5×10(5) human cells within ventricular-wall corresponding to the injection-sites which was further confirmed on Micro-CT. PCR and IHC verified intra-myocardial presence via detection of human-specific β-2-microglobulin, MHC-1, ALU-Sequence and anti-FITC targeting the fluorochrome-labeled part of the MPIOs. The cells appeared viable, integrated and were found in clusters or in the interstitial-spaces. Flow-Cytometry confirmed intra-myocardial presence, and showed further distribution within the spleen, lungs, kidneys and brain. Following IPI, MRI indicated the cells within the intra-peritoneal-cavity involving the liver and kidneys. Flow-Cytometry detected the cells within spleen, lungs, kidneys, thymus, bone-marrow and intra-peritoneal lavage, but not within the heart. For the first time we demonstrate the feasibility of intra-uterine, intra-myocardial stem-cell transplantation into the pre-immune fetal-sheep after MI. Utilizing cell-tracking strategies comprising advanced imaging-technologies and in-vitro tracking-tools, this novel model may serve as a unique platform to assess human cell-fate after intra-myocardial transplantation without the necessity of immunosuppressive-therapy.
authors.affiliation: Swiss Centre for Regenerative Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: Maximilian Y
authors.initials: MY
authors.lastname: Emmert
authors.forename: Benedikt
authors.initials: B
authors.lastname: Weber
authors.forename: Petra
authors.initials: P
authors.lastname: Wolint
authors.forename: Thomas
authors.initials: T
authors.lastname: Frauenfelder
authors.forename: Steffen M
authors.initials: SM
authors.lastname: Zeisberger
authors.forename: Luc
authors.initials: L
authors.lastname: Behr
authors.forename: Sebastien
authors.initials: S
authors.lastname: Sammut
authors.forename: Jacques
authors.initials: J
authors.lastname: Scherman
authors.forename: Chad E
authors.initials: CE
authors.lastname: Brokopp
authors.forename: Ruth
authors.initials: R
authors.lastname: Schwartländer
authors.forename: Viola
authors.initials: V
authors.lastname: Vogel
authors.forename: Peter
authors.initials: P
authors.lastname: Vogt
authors.forename: Jürg
authors.initials: J
authors.lastname: Grünenfelder
authors.forename: Hatem
authors.initials: H
authors.lastname: Alkadhi
authors.forename: Volkmar
authors.initials: V
authors.lastname: Falk
authors.forename: Andreas
authors.initials: A
authors.lastname: Boss
authors.forename: Simon P
authors.initials: SP
authors.lastname: Hoerstrup
mesh_terms: D000273:Adipose Tissue / Q000166:cytology; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D004195:Disease Models, Animal; D005260:Female; D005333:Fetus / Q000166:cytology; D006801:Humans; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D009203:Myocardial Infarction / Q000628:therapy*; D011247:Pregnancy; D012756:Sheep; D014599:Uterus / Q000166:cytology