Fig. 8: CD34⁺ sorted cells have a functional pacemaker phenotype.

a Representative optical action potential traces of day 25 MACS sorted CD34⁺ and CD34⁻ cells, FACS sorted SIRPA⁺CD90⁻NKX2–5⁻ SANLPCs, as well as ALCMs and VLCMs generated from the HES3 NKX2–5^eGFP/w hPSC line. b Optical action potential parameters analyzed in the indicated cell types (MACS pre-sort, n = 46; MACS CD34⁺, n = 47; MACS CD34⁻, n = 43; SANLPC, n = 57; ALCM, n = 79; VLCM, n = 51 cell aggregates from three biological replicates (independent differentiations) for each cell type). Statistical analysis was performed using Kruskal-Wallis test followed by Dunn’s post hoc test: *p < 0.05, **p < 0.01, ***p < 0.001 vs. indicated sample. c Schematic overview of the experimental design used to assess the pacemaker capacity of the CD34⁺ cardiomyocytes in vitro. d Representative bright field images (left) and color-coded activation maps (right) of a VLCM monolayer before and ~4 weeks after the addition of a VLCM control aggregate (n = 12 independent experiments from three biological replicates (independent differentiations)). e Representative bright field images (left) and color-coded activation maps (right) of a VLCM monolayer before and ~4 weeks after the addition of a MACS-sorted CD34⁺ cardiomyocyte (CM) aggregate (n = 10 independent experiments from three biological replicates (independent differentiations)). Scale bars, 1000 μm. Violin plot elements: center line, median; lower line, first quartile; upper line, third quartile. APD30/90, Action potential duration at 30%/90% repolarization. Source data are provided as a Source Data file. Schematics in (c) were generated using Biorender (https://biorender.com).