Injection of wild type embryonic stem cells into Mst1 transgenic blastocysts prevents adult-onset cardiomyopathy

Abstract

Embryonic stem cells have the capacity to differentiate into a wide range of cell types. We previously described that blastocyst injection of wild type (WT) embryonic stem cells (ESCs) into various knockout (KO) mouse models of human disease prevents disease from occurring. In this study we ask if the blastocyst approach can also correct defects in a mouse model of transgenic (Tg) overexpression of a pro-apoptotic factor. We injected ROSA26 (LacZ-marked) WT ESCs into human mammalian sterile 20 like-kinase 1 (Mst1) Tg blastocysts. Mst1 Tg mice overexpress Mst1, a pro-apoptotic factor, in a cardiac-specific manner. As a result, Mst1 Tg mice develop adult dilated cardiomyopathy driven by apoptosis, reduction in cell density and no hypertrophic compensation. Incorporation of WT ESCs generated WT/Mst1 chimeric mice with normal hearts at histological and functional levels. Accordingly, apoptosis and cell density parameters were normalized. The experiments suggest that an adult-onset cardiac myopathy induced by overexpression of the pro-apoptotic Mst1 can be reversed by developmental incorporation of WT ESCs. The findings also suggest that since forced expression of the Mst1 transgene is not abolished in the rescued chimeras, the WT ES-derived cells normalize pathways that lie downstream of Mst1. The results expand the therapeutic capability of the ESCs to mouse models that overproduce detrimental proteins.

Fig. 1

ESCs reverse cardiomyopathy in WT/Mst1 chimeras. a–c Immunofluorescence showing detection of Mst1 in Mst1 transgenic (c) and WT/Mst1 chimeric (b) (note patchy areas of Mst1 staining in the WT/Mst1 chimera), but not in WT (a) heart sections. a inset: WB showing detection of Mst1 (red arrowhead) in Mst1 transgenic (right lane) and WT/Mst1 chimeric (center lane), but not in WT (left lane) hearts (blue arrowhead: tubulin control). d–f H&E staining showing reversion of dilated cardiomyopathy in the WT/Mst1 chimeric hearts (yellow dotted circle demarcates the left ventricle). g–i Masson Trichrome staining showing reduction of fibrosis (yellow arrows) in WT/Mst1 chimeric hearts. DAPI in blue (a–c) demarcates nuclei. Magnification: 100× (a–c); 10× (d–f) and 400× (g–i)