title: Paracrine effects of mesenchymal stem cells enhance vascular regeneration in ischemic murine skin.
abstract: New theories on the regeneration of ischemic vasculature have emerged indicating a pivotal role of adult stem cells. The aim of this study was to investigate homing and hemodynamic effects of circulating bone marrow-derived mesenchymal stem cells (MSCs) in a critically ischemic murine skin flap model. Bone marrow-derived mesenchymal stem cells (Lin(-)CD105(+)) were harvested from GFP(+)-donor mice and transferred to wildtype C57BL/6 mice. Animals receiving GFP(+)-fibroblasts served as a control group. Laser scanning confocal microscopy and intravital fluorescence microscopy were used for morphological analysis, monitoring and quantitative assessment of the stem cell homing and microhemodynamics over two weeks. Immunohistochemical staining was performed for GFP, eNOS, iNOS, VEGF. Tissue viability was analyzed by TUNEL-assay. We were able to visualize perivascular homing of MSCs in vivo. After 4 days, MSCs aligned along the vascular wall without undergoing endothelial or smooth muscle cell differentiation during the observation period. The gradual increase in arterial vascular resistance observed in the control group was abolished after MSC administration (P<0.01). At capillary level, a strong angiogenic response was found from day 7 onwards. Functional capillary density was raised in the MSC group to 197% compared to 132% in the control group (P<0.01). Paracrine expression of VEGF and iNOS, but not eNOS could be shown in the MSC group but not in the controls. In conclusion, we demonstrated that circulating bone marrow-derived MSCs home to perivascular sites in critically ischemic tissue, exhibits paracrine function and augment microhemodynamics. These effects were mediated through arteriogenesis and angiogenesis, which contributed to vascular regeneration.
authors.affiliation: Department of Clinical Research, University of Bern, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Schlosser
authors.forename: Cyrill
authors.initials: C
authors.lastname: Dennler
authors.forename: Riccardo
authors.initials: R
authors.lastname: Schweizer
authors.forename: Daniel
authors.initials: D
authors.lastname: Eberli
authors.forename: Jens V
authors.initials: JV
authors.lastname: Stein
authors.forename: Volker
authors.initials: V
authors.lastname: Enzmann
authors.forename: Pietro
authors.initials: P
authors.lastname: Giovanoli
authors.forename: Dominique
authors.initials: D
authors.lastname: Erni
authors.forename: Jan A
authors.initials: JA
authors.lastname: Plock
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000473:pathology*; D000071063:Endoglin; D005260:Female; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006439:Hemodynamics; D007150:Immunohistochemistry / Q000379:methods; D020287:In Situ Nick-End Labeling; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal / Q000379:methods; D019899:Paracrine Communication; D015203:Reproducibility of Results; D012867:Skin / Q000473:pathology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
chemical_list: D000071063:Endoglin; C502004:Eng protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D042461:Vascular Endothelial Growth Factor A; D049452:Green Fluorescent Proteins