Gata4-Dependent Differentiation of c-Kit+-Derived Endothelial Cells Underlies Artefactual Cardiomyocyte Regeneration in the Heart.
BACKGROUND
Although c-Kit+ adult progenitor cells were initially reported to produce new cardiomyocytes in the heart, recent genetic evidence suggests that such events are exceedingly rare. However, to determine if these rare events represent true de novo cardiomyocyte formation, we deleted the necessary cardiogenic transcription factors Gata4 and Gata6 from c-Kit-expressing cardiac progenitor cells.


METHODS
Kit allele-dependent lineage tracing and fusion analysis were performed in mice following simultaneous Gata4 and Gata6 cell type-specific deletion to examine rates of putative de novo cardiomyocyte formation from c-Kit+ cells. Bone marrow transplantation experiments were used to define the contribution of Kit allele-derived hematopoietic cells versus Kit lineage-dependent cells endogenous to the heart in contributing to apparent de novo lineage-traced cardiomyocytes. A Tie2CreERT2 transgene was also used to examine the global impact of Gata4 deletion on the mature cardiac endothelial cell network, which was further evaluated with select angiogenesis assays.


RESULTS
Deletion of Gata4 in Kit lineage-derived endothelial cells or in total endothelial cells using the Tie2CreERT2 transgene, but not from bone morrow cells, resulted in profound endothelial cell expansion, defective endothelial cell differentiation, leukocyte infiltration into the heart, and a dramatic increase in Kit allele-dependent lineage-traced cardiomyocytes. However, this increase in labeled cardiomyocytes was an artefact of greater leukocyte-cardiomyocyte cellular fusion because of defective endothelial cell differentiation in the absence of Gata4.


CONCLUSIONS
Past identification of presumed de novo cardiomyocyte formation in the heart from c-Kit+ cells using Kit allele lineage tracing appears to be an artefact of labeled leukocyte fusion with cardiomyocytes. Deletion of Gata4 from c-Kit+ endothelial progenitor cells or adult endothelial cells negatively impacted angiogenesis and capillary network integrity.
['Maliken|Bryan D|BD|', 'Kanisicak|Onur|O|', 'Karch|Jason|J|', 'Khalil|Hadi|H|', 'Fu|Xing|X|', 'Boyer|Justin G|JG|', 'Prasad|Vikram|V|', 'Zheng|Yi|Y|', 'Molkentin|Jeffery D|JD|']
D000818:Animals D016026:Bone Marrow Transplantation D002459:Cell Fusion D019070:Cell Lineage D049109:Cell Proliferation D058948:Cell Tracking D002478:Cells, Cultured D042783:Endothelial Cells D005260:Female D050991:GATA4 Transcription Factor D050993:GATA6 Transcription Factor D007962:Leukocytes D008297:Male D008810:Mice, Inbred C57BL D018345:Mice, Knockout D032383:Myocytes, Cardiac D018919:Neovascularization, Physiologic D019009:Proto-Oncogene Proteins c-kit D012038:Regeneration D015398:Signal Transduction
regeneration angiogenesis mice, transgenic myocardial infarction myocytes, cardiac