(A) Microtubule polymerization kinetics in the presence or absence of 17β-estradiol (E2). Quantification of time to half max in the presence of ethanol vehicle, 20 nM 17β-estradiol, and 200 nM 17β-estradiol (E2). Representative confocal micrographs of iPSC-CMs stained with β-tubulin (orange, B), detyrosinated β-tubulin (purple, C), and DAPI (blue). Quantification of total microtubule (B) and detyrosinated microtubule (C) density. (D) E2 treatment increased RV function and estimated RV–pulmonary artery coupling but did not reduce right ventricular systolic pressure. RVFWT, RV free wall thickening. (E) Wheat germ agglutinin (WGA) (green) and microtubule staining (orange) of RV free wall sections from control, PAB-Vehicle, and PAB-E2 RV sections with quantification of relative microtubule fluorescence intensity. (F) WGA (green) delineated cardiomyocyte size. Values represent median area (black, blue, and purple). (G) 17β-Estradiol reduced nuclear size (white arrows), restored the normal striated t-tubule architecture in RV sections, and prevented lateralization of connexin-43 (purple) in the RV (red arrows: lateralized connexin-43, white arrows: connexin-43 at intercalated disc). Data are depicted as mean ± SD if normally distributed or median ± range if distribution was not normal. P values determined by 1-way ANOVA with Tukey’s multiple comparisons test or Brown-Forsythe ANOVA and Dunnett’s T3 multiple comparisons test.