Three‐dimensional (3D) cultures of human pluripotent stem cell derived cardiomyocytes (hPSC‐CMs) hold great promise for drug discovery, providing a better approximation to the in vivo physiology over standard two‐dimensional (2D) monolayer cultures. However, the transition of CM differentiation protocols from 2D to 3D cultures is not straightforward. In this work, we relied on the aggregation of hPSC‐derived cardiac progenitors and their culture under agitated conditions to generate highly pure cardiomyocyte aggregates. Whole‐transcriptome analysis and 13C‐metabolic flux analysis allowed to demonstrate at both molecular and fluxome levels that such 3D culture environment enhances metabolic maturation of hiPSC‐CMs. When compared to 2D, 3D cultures of hiPSC‐CMs displayed down‐regulation of genes involved in glycolysis and lipid biosynthesis and increased expression of genes involved in OXPHOS. Accordingly, 3D cultures of hiPSC‐CMs had lower fluxes through glycolysis and fatty acid synthesis and increased TCA‐cycle activity. Importantly, we demonstrated that the 3D culture environment reproducibly improved both CM purity and metabolic maturation across different hPSC lines, thereby providing a robust strategy to derive enriched hPSC‐CMs with metabolic features closer to that of adult CMs.

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Sea urchins are common inhabitants of wave-swept shores. To withstand the action of waves, they rely on highly specialized independent adhesive organs, the adoral tube feet. The latter are extremely well-designed for temporary adhesion being composed by two functional subunits: (1) an apical disc that produces an adhesive secretion to fasten the sea urchin to the substratum, as well as a deadhesive secretion to allow the animal to move and (2) a stem that bears the tensions placed on the animal by hydrodynamism. Despite their technological potential for the development of new biomimetic underwater adhesives, very little is known about the biochemical composition of sea urchin adhesives. A characterization of sea urchin adhesives is presented using footprints. The latter contain inorganic residues (45.5%), proteins (6.4%), neutral sugars (1.2%), and lipids (2.5%). Moreover, the amino acid composition of the soluble protein fraction revealed a bias toward six amino acids: glycine, alanine, valine, serine, threonine, and asparagine/aspartic acid, which comprise 56.8% of the total residues. In addition, it also presents higher levels of proline (6.8%) and half-cystine (2.6%) than average eukaryotic proteins. Footprint insolubility was partially overcome using strong denaturing and reducing buffers, enabling the visualization of 13 proteins by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The conjugation of mass spectrometry with homology-database search allowed the identification of six proteins: alpha and beta tubulin, actin, and histones H2B, H3, H2A, and H4, whose location and function in the adhesive are discussed but require further investigation. For the remaining unidentified proteins, five de novo-generated peptide sequences were found that were not present in the available protein databases, suggesting that they might be novel or modified proteins.