Representative micrographs of the LV scar area stained with rat endothelial cell antigen-1 (RECA-1+) to visualize host blood vessels in failing rat hearts treated with (A) SASG implanted through lateral thoracotomy; (B) FGs implanted by thoracotomy (FG); (C) SASG implanted by minimally invasive SASG-VATS; (D) FGs implanted though VATS (FG-VATS); or in (E) untreated (MI) rats, 4 weeks after treatment; (200×). RECA-1+ blood vessels (red), nuclei (DAPI, blue). Scale bar indicates 50 μm. (F) The LV scar area in SASG and SASG-VATS contains a rich network of blood vessels. The number of RECA-1+ blood vessels in the LV scar area per 200×field was higher in SASG-treated hearts than FG (P<0.001) and MI hearts (****P<0.0001). Similarly, SASG-VATS hearts had more vasculature than FG-VATS (P<0.01), and MI (**P<0.01). Host RECA-1+ vasculature were also observed within the graft area of SASG (G) and SASG-VATS (H). Confocal micrographs of the epicardial graft and LV scar area after perfusion with 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) to visualize functional blood vessels in failing rat hearts treated with SASG and SASG-VATS (I–K). Merged xy confocal image with the transmitted light channel of the epicardial graft area showing the presence of functional blood vessels throughout the implanted graft (100×) (I). Inset of image (200×and 400×) correspond to 3D reconstruction of z-stacks from the same area showing blood vessel networks surrounding and penetrating the ECM of a spheroid embedded in the graft. Abundant sprouting of neo-vessels was seen within the spheroid's ECM (arrows). Dotted line indicates host/graft interface. Right panel in (I) shows xy of the inset merged with the transmitted light channel and DAPI (blue). Three-dimensional images of angiogenic sprouts and pseudopodial processes at a viewing angle of 0° in the LV scar area of SASG- (J) and SASG-VATS-treated hearts (K). Left panel corresponds to merged xy confocal image with the transmitted light channel, whereas right panels correspond to 3D reconstruction of z-stacks from the same area. Arrows in (J, K) indicate angiogenic sprouts in the LV ischemic area. ECM, extracellular matrix.