Active Wnt signaling in response to cardiac injury.
Although the contribution of Wnt signaling in infarct healing is suggested, its exact role after myocardial infarction (MI) still needs to be unraveled. We evaluated the cardiac presence of active Wnt signaling in vivo following MI, and investigated in which cell types active Wnt signaling was present by determining Axin2 promoter-driven LacZ expression. C57BL/6 Axin2-LacZ reporter mice were sacrificed at days 0, 1, 3, 7, 14, and 21 after LAD ligation. Hearts were snap-frozen for immunohistochemistry (IHC) or enzymatically digested to obtain a single cell suspension for flow cytometric analysis. For both FACS and IHC, samples were stained for beta-galactosidase and antibodies against Sca-1, CD31, ckit, and CD45. Active Wnt signaling increased markedly in the myocardium, from 7 days post-MI onwards. Using Sca-1 and CD31, to identify progenitor and endothelial cells, a significant increase in LacZ+ cells was found at 7 and 14 days post-MI. LacZ+ cells also increased in the ckit+ and CD45+ cell population. IHC revealed LacZ+ cells co-expressing Sca, CD31, CD45, vWF, and alphaSMA in the border zone and the infarcted area. Wnt signaling increased significantly after MI in Sca+- and CD31+-expressing cells, suggesting involvement of Wnt signaling in resident Sca+ progenitor cells, as well as endothelial cells. Moreover, active Wnt signaling was present in ckit+ cells, leukocytes, and fibroblast. Given its broad role during the healing phase after cardiac injury, additional research seems warranted before a therapeutic approach on Wnt to enhance cardiac regeneration can be carried out safely.
Oerlemans
Martinus I F J
MI
Department of Cardiology, University Medical Centre Utrecht, The Netherlands.
Goumans
Marie-José
MJ
van Middelaar
Ben
B
Clevers
Hans
H
Doevendans
Pieter A
PA
Sluijter
Joost P G
JP
D000818:Animals; D060466:Axin Protein; D002452:Cell Count; D003598:Cytoskeletal Proteins / Q000235:genetics; D042783:Endothelial Cells / Q000166:cytology / Q000502:physiology; D005260:Female; D005434:Flow Cytometry; D017930:Genes, Reporter; D007763:Lac Operon / Q000235:genetics; D007962:Leukocytes / Q000166:cytology / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D009203:Myocardial Infarction / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D012038:Regeneration / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology / Q000502:physiology; D051153:Wnt Proteins / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology*
D060466:Axin Protein; C111729:Axin2 protein, mouse; D003598:Cytoskeletal Proteins; D051153:Wnt Proteins