Fig. 1.

Modest effects of MSC transplantation in infarcted myocardium. (A) Incidence of sudden death for normal (n = 12), sham-injected (n = 27), and MSC-transplanted (n = 19) rats during 11 d after transplantation. All rats that died during the procedure or immediately after cell implantation were excluded from the study (SI Appendix, SI Methods). (B) Triphenyltetrazolium chloride staining for determination of left ventricle infarct size. (Scale bar: 2 mm.) (C) Masson trichrome staining for determination of fibrosis area. (Magnification: 200×. Scale bars: Upper, 2 mm; Lower, 100 μm.) (D) TUNEL assay for the number of apoptotic cells. Representative site for TUNEL assay is the same as the Masson trichrome-stained region. Apoptotic nuclei are shown by white arrow. (Magnification: 200×. Scale bar: 100 μm). (E) H&E staining for identification of inflammatory cell infiltrates. (Magnification: 200×. Scale bar: 20 μm.) (F) Ectopic beats at border zone in normal and sham- and MSC-injected myocardium. (G) Local CVs were measured at the border zone in sham-treated (n = 8) and MSC-engrafted (n = 7) hearts. (H) VT or VF inducibility in normal (n = 12, Top), sham-treated (n = 13, Middle), or MSC-treated hearts (n = 9, Bottom). Arrows indicate electrical stimulation. (I) Sequential voltage map images during VT in the MSC-engrafted heart. Red circles and white arrows indicate the MSC-injected region and the direction of wavefront propagation, respectively. Right: Diagram shows an optical recording of the action potentials. All data are expressed as means ± SEM (*P < 0.05, **P < 0.01, ***P < 0.001).