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Cardiomyocytes fuse with surrounding noncardiomyocytes and reenter the cell cycle.

Matsuura K, Wada H, Nagai T, Iijima Y, Minamino T, Sano M, Akazawa H, Molkentin JD, Kasanuki H, Komuro I - J. Cell Biol. (2004)

Bottom Line: Furthermore, cardiomyocytes reentered the G2-M phase in the cell cycle after fusing with proliferative noncardiomyocytes.Transplanted endothelial cells or skeletal muscle-derived cells fused with adult cardiomyocytes in vivo.In the cryoinjured heart, there were Ki67-positive cells that expressed both cardiac and endothelial lineage marker proteins.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan.

ABSTRACT
The concept of the plasticity or transdifferentiation of adult stem cells has been challenged by the phenomenon of cell fusion. In this work, we examined whether neonatal cardiomyocytes fuse with various somatic cells including endothelial cells, cardiac fibroblasts, bone marrow cells, and endothelial progenitor cells spontaneously in vitro. When cardiomyocytes were cocultured with endothelial cells or cardiac fibroblasts, they fused and showed phenotypes of cardiomyocytes. Furthermore, cardiomyocytes reentered the G2-M phase in the cell cycle after fusing with proliferative noncardiomyocytes. Transplanted endothelial cells or skeletal muscle-derived cells fused with adult cardiomyocytes in vivo. In the cryoinjured heart, there were Ki67-positive cells that expressed both cardiac and endothelial lineage marker proteins. These results suggest that cardiomyocytes fuse with other cells and enter the cell cycle by maintaining their phenotypes.

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HUVEC and cFB acquired the cardiac phenotype through cell fusion with cardiomyocytes. (A) LacZ-expressing cardiomyocytes of neonatal rats were cocultured with GFP+ HUVEC (a–d) or GFP+ cFB (e–h) and stained with mouse monoclonal anti-cTnT (red) and rabbit polyclonal anti-β-gal antibodies (blue). Merged images were obtained from the same confocal plane. GFP+ HUVEC and GFP+ cFB (a and e, arrow) expressed cTnT (b and f, arrow) and β-gal (c and g, arrow) in the same cell (merged on d and h). Arrowheads indicate the nonfused cardiomyocytes. Bars, 50 μm. (B) LacZ-expressing cardiomyocytes of neonatal rats were cocultured with GFP+ HUVEC (a–f) or GFP+ cFB (g–l) and stained with mouse monoclonal anti-cTnT (red) and goat polyclonal anti-GATA4 or rabbit polyclonal anti-ANF or anti-connexin43 antibodies (blue). cTnT-expressing GFP+ HUVEC (a, c, and e) and cTnT-expressing GFP+ cFB (g, i, and k) expressed GATA4 (b and h, arrowhead), ANF (d and j, arrowhead), and connexin43 (f and l, arrowhead). Bars, 50 μm.
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fig1: HUVEC and cFB acquired the cardiac phenotype through cell fusion with cardiomyocytes. (A) LacZ-expressing cardiomyocytes of neonatal rats were cocultured with GFP+ HUVEC (a–d) or GFP+ cFB (e–h) and stained with mouse monoclonal anti-cTnT (red) and rabbit polyclonal anti-β-gal antibodies (blue). Merged images were obtained from the same confocal plane. GFP+ HUVEC and GFP+ cFB (a and e, arrow) expressed cTnT (b and f, arrow) and β-gal (c and g, arrow) in the same cell (merged on d and h). Arrowheads indicate the nonfused cardiomyocytes. Bars, 50 μm. (B) LacZ-expressing cardiomyocytes of neonatal rats were cocultured with GFP+ HUVEC (a–f) or GFP+ cFB (g–l) and stained with mouse monoclonal anti-cTnT (red) and goat polyclonal anti-GATA4 or rabbit polyclonal anti-ANF or anti-connexin43 antibodies (blue). cTnT-expressing GFP+ HUVEC (a, c, and e) and cTnT-expressing GFP+ cFB (g, i, and k) expressed GATA4 (b and h, arrowhead), ANF (d and j, arrowhead), and connexin43 (f and l, arrowhead). Bars, 50 μm.

Mentions: When GFP-expressing (GFP+) HUVEC or GFP+ cFB were cocultured with neonatal rat cardiomyocytes that were infected with the adenoviral vector carrying the LacZ reporter gene, some of GFP+ HUVEC and GFP+ cFB coexpressed both cardiac troponin T (cTnT) and β-galactosidase (β-gal) (Fig. 1 A, a–h, arrows). These GFP- and cTnT-expressing cells also expressed GATA4 (Fig. 1 B, a, b, g, and h, arrowheads), atrial natriuretic factor (ANF) (Fig. 1 B, c, d, i and j, arrowheads), and connexin43 (Fig. 1 B, e, f, k, and l, arrowheads). The expression of the cardiac proteins in GFP+ cells was observed only in the coculture condition and all of cTnT-expressing HUVEC and cFB were positive for β-gal, suggesting that HUVEC and cFB acquired the cardiac phenotype through cell fusion with cardiomyocytes. The cTnT-positive GFP-expressing cells were found in 0.019% of GFP+ HUVEC and 0.004% of GFP+ cFB after 4 d of coculture. To rule out the possibility that noncardiomyocytes were infected with the adenoviral vector carrying the LacZ reporter gene during coculture, we examined the cell fusion by using neonatal cardiomyocytes prepared from GFP transgenic rats and red fluorescent protein-expressing (RFP+) HUVEC or RFP+ cFB. When RFP+ HUVEC or RFP+ cFB were cocultured with GFP+ cardiomyocytes, some of RFP+ HUVEC and RFP+ cFB coexpressed cardiomyocyte-derived GFP and cTnT (Fig. 2 A, a–h, arrows). Some of both GFP- and RFP-expressing (GFP+/RFP+) fused cells expressed GATA4 (Fig. 2 B, a, b, g, and h, arrowheads), ANF (Fig. 2 B, c, d, i, and j, arrowheads), and connexin43 (unpublished data). Live imaging showed that GFP+ cardiomyocytes fused with RFP+ HUVEC beat spontaneously (see Fig. S1 and Video 1, available at http://www.jcb.org/cgi/content/full/jcb.200312111/DC1). They beat regularly and the beating rate was ∼80 beats/min, which was similar to that of cocultured cardiomyocytes, suggesting that cardiomyocyte function was maintained even after fusing with other cells.


Cardiomyocytes fuse with surrounding noncardiomyocytes and reenter the cell cycle.

Matsuura K, Wada H, Nagai T, Iijima Y, Minamino T, Sano M, Akazawa H, Molkentin JD, Kasanuki H, Komuro I - J. Cell Biol. (2004)

HUVEC and cFB acquired the cardiac phenotype through cell fusion with cardiomyocytes. (A) LacZ-expressing cardiomyocytes of neonatal rats were cocultured with GFP+ HUVEC (a–d) or GFP+ cFB (e–h) and stained with mouse monoclonal anti-cTnT (red) and rabbit polyclonal anti-β-gal antibodies (blue). Merged images were obtained from the same confocal plane. GFP+ HUVEC and GFP+ cFB (a and e, arrow) expressed cTnT (b and f, arrow) and β-gal (c and g, arrow) in the same cell (merged on d and h). Arrowheads indicate the nonfused cardiomyocytes. Bars, 50 μm. (B) LacZ-expressing cardiomyocytes of neonatal rats were cocultured with GFP+ HUVEC (a–f) or GFP+ cFB (g–l) and stained with mouse monoclonal anti-cTnT (red) and goat polyclonal anti-GATA4 or rabbit polyclonal anti-ANF or anti-connexin43 antibodies (blue). cTnT-expressing GFP+ HUVEC (a, c, and e) and cTnT-expressing GFP+ cFB (g, i, and k) expressed GATA4 (b and h, arrowhead), ANF (d and j, arrowhead), and connexin43 (f and l, arrowhead). Bars, 50 μm.
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fig1: HUVEC and cFB acquired the cardiac phenotype through cell fusion with cardiomyocytes. (A) LacZ-expressing cardiomyocytes of neonatal rats were cocultured with GFP+ HUVEC (a–d) or GFP+ cFB (e–h) and stained with mouse monoclonal anti-cTnT (red) and rabbit polyclonal anti-β-gal antibodies (blue). Merged images were obtained from the same confocal plane. GFP+ HUVEC and GFP+ cFB (a and e, arrow) expressed cTnT (b and f, arrow) and β-gal (c and g, arrow) in the same cell (merged on d and h). Arrowheads indicate the nonfused cardiomyocytes. Bars, 50 μm. (B) LacZ-expressing cardiomyocytes of neonatal rats were cocultured with GFP+ HUVEC (a–f) or GFP+ cFB (g–l) and stained with mouse monoclonal anti-cTnT (red) and goat polyclonal anti-GATA4 or rabbit polyclonal anti-ANF or anti-connexin43 antibodies (blue). cTnT-expressing GFP+ HUVEC (a, c, and e) and cTnT-expressing GFP+ cFB (g, i, and k) expressed GATA4 (b and h, arrowhead), ANF (d and j, arrowhead), and connexin43 (f and l, arrowhead). Bars, 50 μm.
Mentions: When GFP-expressing (GFP+) HUVEC or GFP+ cFB were cocultured with neonatal rat cardiomyocytes that were infected with the adenoviral vector carrying the LacZ reporter gene, some of GFP+ HUVEC and GFP+ cFB coexpressed both cardiac troponin T (cTnT) and β-galactosidase (β-gal) (Fig. 1 A, a–h, arrows). These GFP- and cTnT-expressing cells also expressed GATA4 (Fig. 1 B, a, b, g, and h, arrowheads), atrial natriuretic factor (ANF) (Fig. 1 B, c, d, i and j, arrowheads), and connexin43 (Fig. 1 B, e, f, k, and l, arrowheads). The expression of the cardiac proteins in GFP+ cells was observed only in the coculture condition and all of cTnT-expressing HUVEC and cFB were positive for β-gal, suggesting that HUVEC and cFB acquired the cardiac phenotype through cell fusion with cardiomyocytes. The cTnT-positive GFP-expressing cells were found in 0.019% of GFP+ HUVEC and 0.004% of GFP+ cFB after 4 d of coculture. To rule out the possibility that noncardiomyocytes were infected with the adenoviral vector carrying the LacZ reporter gene during coculture, we examined the cell fusion by using neonatal cardiomyocytes prepared from GFP transgenic rats and red fluorescent protein-expressing (RFP+) HUVEC or RFP+ cFB. When RFP+ HUVEC or RFP+ cFB were cocultured with GFP+ cardiomyocytes, some of RFP+ HUVEC and RFP+ cFB coexpressed cardiomyocyte-derived GFP and cTnT (Fig. 2 A, a–h, arrows). Some of both GFP- and RFP-expressing (GFP+/RFP+) fused cells expressed GATA4 (Fig. 2 B, a, b, g, and h, arrowheads), ANF (Fig. 2 B, c, d, i, and j, arrowheads), and connexin43 (unpublished data). Live imaging showed that GFP+ cardiomyocytes fused with RFP+ HUVEC beat spontaneously (see Fig. S1 and Video 1, available at http://www.jcb.org/cgi/content/full/jcb.200312111/DC1). They beat regularly and the beating rate was ∼80 beats/min, which was similar to that of cocultured cardiomyocytes, suggesting that cardiomyocyte function was maintained even after fusing with other cells.

Bottom Line: Furthermore, cardiomyocytes reentered the G2-M phase in the cell cycle after fusing with proliferative noncardiomyocytes.Transplanted endothelial cells or skeletal muscle-derived cells fused with adult cardiomyocytes in vivo.In the cryoinjured heart, there were Ki67-positive cells that expressed both cardiac and endothelial lineage marker proteins.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine, Chiba 260-8670, Japan.

ABSTRACT
The concept of the plasticity or transdifferentiation of adult stem cells has been challenged by the phenomenon of cell fusion. In this work, we examined whether neonatal cardiomyocytes fuse with various somatic cells including endothelial cells, cardiac fibroblasts, bone marrow cells, and endothelial progenitor cells spontaneously in vitro. When cardiomyocytes were cocultured with endothelial cells or cardiac fibroblasts, they fused and showed phenotypes of cardiomyocytes. Furthermore, cardiomyocytes reentered the G2-M phase in the cell cycle after fusing with proliferative noncardiomyocytes. Transplanted endothelial cells or skeletal muscle-derived cells fused with adult cardiomyocytes in vivo. In the cryoinjured heart, there were Ki67-positive cells that expressed both cardiac and endothelial lineage marker proteins. These results suggest that cardiomyocytes fuse with other cells and enter the cell cycle by maintaining their phenotypes.

Show MeSH
Related in: MedlinePlus