title: Hybrid cardiomyocytes derived by cell fusion in heterotopic cardiac xenografts.
abstract: Cardiomyocytes expressing host markers, such as the Y chromosome in sex-mismatched transplants, have been described in human allografts, suggesting that circulating cells can contribute to cardiac regeneration. It has not been established, however, whether host-derived cardiomyocytes result from transdifferentiation of stem cells or cell fusion. To address this issue, we used heterotopic heart xenografts and looked for markers of donor and recipient cells. Golden Syrian hamsters or transgenic mice expressing nuclear beta-galactosidase under the control of the cardiac troponin I promoter served as organ donors, while GFP+ transgenic rats were used as recipients. GFP+ cells, including abundant CD-45+ inflammatory cells and rare undifferentiated cells expressing early cardiac markers (GATA-4 or MEF2C), were found in xenografts harvested two weeks after surgery. In addition, rare GFP+ mature cardiomyocytes were found in 7 of 8 hamster xenografts and 6 of 6 mouse xenografts. The proportion of these cells was very low (0.0001% to 0.0344% in hamster xenografts) but similar to the one observed in control rat heart allografts. Without exception, all GFP+ cardiomyocytes also expressed donor markers, i.e., hamster membrane antigens or lacZ, so they must derive from cell fusion, not transdifferentiation.
authors.affiliation: Department of Medical and Surgical Sciences, University of Padova, Padova, Italy.
authors.forename: Arben
authors.initials: A
authors.lastname: Dedja
authors.forename: Tania
authors.initials: T
authors.lastname: Zaglia
authors.forename: Luigi
authors.initials: L
authors.lastname: Dall'Olmo
authors.forename: Tatiana
authors.initials: T
authors.lastname: Chioato
authors.forename: Gaetano
authors.initials: G
authors.lastname: Thiene
authors.forename: Luca
authors.initials: L
authors.lastname: Fabris
authors.forename: Ermanno
authors.initials: E
authors.lastname: Ancona
authors.forename: Stefano
authors.initials: S
authors.lastname: Schiaffino
authors.forename: Simonetta
authors.initials: S
authors.lastname: Ausoni
authors.forename: Emanuele
authors.initials: E
authors.lastname: Cozzi
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015415:Biomarkers; D002459:Cell Fusion; D006224:Cricetinae; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D016027:Heart Transplantation; D051379:Mice; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014183:Transplantation, Heterologous; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D015415:Biomarkers; D049452:Green Fluorescent Proteins; D001616:beta-Galactosidase