Sublethal caspase activation enhances cardiac differentiation.

<p>(A) GFP expression levels in EBs exposed to vehicle or 100 nM STS +/- Q-VD-OPH (upper panels) and then cultured for additional 96 h (lower panels). Cardiac α-MHC promoter was driving GFP expression and differentiation was indicated as increase in GFP fluorescence compared to control. (B) In GFP negative zones of the EBs, new GFP positive cells were observed upon STS treatment. (C) Prospective long-term imaging of GFP expression in EBs exposed to control vehicle, 100 nM STS or 100 nM STS + Q-VD-OPH for 5 h and GFP expression was monitored during the following 72 h. (D) GFP expression level is expressed as the ratio between GFP levels at 72 h over GFP levels at 5 h, as monitored in individual, single cells. Relative mRNA expression levels of TnT (E), α-MHC (F), Nkx 2.5 (G) and Oct-4 (H) in EBs exposed to STS +/- Q-VD-OPH and collected for analysis after 3 and 7 days. Arrow indicates an individual, single cell after 5 h exposure to STS, which is then followed for 72 h,*p<0.05 vs control, ***p <0.001 vs control, ### p<0.001 vs STS.