Fig. 1

Space microgravity leads to cardiomyocyte adaptative changes. a A schematic of all experimental processes, including somatic reprogramming, cardiomyocyte preparation, and cell treatment during the SZ-13 mission. b The representative pictures of culture flasks and apparatus for cell maintenance on the CSS. c The representative images of GCaMP-CMs under space microgravity (μg) and simulated 1 g (1g) conditions on the CSS. d The quantitative analyses on cell size of GCaMP-CMs in 1 g and μg groups. e The quantitative comparison on MFI (mean fluorescence intensity) for peak calcium density of GCaMP-CMs under 1 g and μg conditions. f The beating rate analyses of GCaMP-CMs under 1 g and μg conditions. g Representative calcium transients of GCaMP-CMs. The quantitative analyses of amplitude (h), time to peak (i), decay time (j) and tau (k) of GCaMP-CMs under 1 g and μg conditions. l Immunofluorescence staining of cytoskeleton proteins in hPSC-CMs under 1 g and μg conditions (α-Actinin, green; cTnT, red; Hoechst 33342, blue). m Representative polar histogram of myofibrillar alignment in hPSC-CMs under 1 g and μg conditions. The quantitative analyses on sarcomere length (n) and cTnT content (o) under 1 g and μg conditions. p The relative mRNA expression of cardiomyocyte-specific cytoskeleton genes (MYH6, MYH7, TNNT2, TNNI1, TNNI3) in hPSC-CMs under 1 g and μg conditions. q The protein expression of TNNI1 and TNNI3. r The relative mRNA expression of cardiomyocyte-specific calcium handling genes (RYR2, ATP2A2, SLC8A1, CACNA1C) in hPSC-CMs under 1 g and μg conditions. Data are presented as mean ± SEM; Student’s t test; *P < 0.05, **P < 0.01, ns not significant