G418-selected PSC-derived cardiomyocytes are functionally integrated with the host myocardium.

<p>(a) The presence of EGFP⁺ PSC-derived cardiomyocyte in the host heart at 2 weeks post transplant. (b) α-actinin immunofluorescence of the same donor cell as in (a). (c) Merge of (a) and (b). (d-f) Two-photon laser scanning microscopy revealed synchronous action potential-evoked calcium transients in the EGFP⁺ donor cell and its adjacent EGFP^-host cardiomyocytes. (d) 2-D images taken at 16-μm <i>z</i>-steps across an EGFP⁺ donor (D) myocyte and its surrounding host (H) myocytes. The heart was being paced at a frequency of 3 Hz during image acquisition. Periodic increases in rhod-2 fluoresence intensity reflect increases in cytosolic calcium in response to propagating action potentials and span the entire width of the image, including the EGFP⁺ donor cell. The dotted line denotes the position of the scan line for line-scan imaging. (e) Line average as a function of time for the portions of the dotted scan line indicated by brackets in (d). Line scans were obtained during spontaneous sinus rhythm and during electrical pacing at 3 Hz. Action potential-evoked calcium transients in the host myocyte are in phase with those in the neighboring host myocytes. (f) Superimposition of normalized calcium transients for the donor and host myocytes, demonstrating similar kinetics of the transients in both cell types.