Figure 3.

Notch Signaling Enhances Vascularization with Similar Infarct Size at 1 Month Post-Implantation

(A) Average infarct area is assessed by histology and normalized to left ventricular (LV) area at 4 weeks. (B) Anterior wall thickness by histology is shown for an area approximately 4 mm from the apex of the heart. Values are in mm. (C and D) Picrosirius red and fast green counterstain were used to identify fibrotic regions that are quantified in (A). Representative images are shown for both control + hESC-CMs (C) and Delta + hESC-CMs (D), where the black arrow identifies a region of human myocardial graft within the infarct. Scale bars, 2.5 mm. (E and F) Inflammatory response at 4 weeks by CD68 staining normalized to infarct area. Outlined regions of interest in (C) and (D) are shown at higher magnification in (E) and (F). Serial sections are stained with CD68 antibody to label monocytes and macrophages and visualized with diaminobenzidine (DAB) (brown). Scale bars, 200 μm. (G and H) Host-derived vessels are identified by staining with CD31 antibody (red) (G and H) with a double stain for βMHC (green) (G) to identify hESC-CM grafts within the infarct regions. Scale bar, 200 μm. (I) Level of inflammatory response is expressed as CD68⁺ area normalized to scar area by picrosirius red at 2 and 4 weeks. Values for 2 week time point were obtained through pilot study experiments shown in Figure S4. (J) Level of neovascularization is quantified as CD31⁺ lumens within βMHC⁺ graft regions. p-values were calculated using an unpaired two-tailed t-test. For (A), (B), (F), and (G), ∗p < 0.05. Error bars indicate SEM.