Project description:Thyroid hormone (TH) levels are low during development, and the deiodinases control TH signaling through tissue-specific activation or inactivation of TH. Here we studied human iPSC-derived hepatic organoids and identified a robust induction in DIO2 expression (the deiodinase that activates T4 to T3) that occurs in hepatoblasts. The surge in D2-T3 persists until the hepatoblasts differentiate into hepatocytes- or cholangiocytes-like cells, neither of which express DIO2. Preventing the induction of the D2-T3 signaling modified the expression of key transcription factors, decreased the number of hepatocyte-like cells by ~60%, and increased the number of cholangiocyte-like cells by ~55% without affecting the growth or the size of the mature liver organoid. Physiological levels of T3 could not fully restore the transition from hepatoblasts to mature cells. This indicates that the timed surge in D2-T3 signaling critically determines the fate of developing human hepatoblasts and the transcriptome of the maturing hepatocytes, with physiological and clinical implications for how the liver handles energy substrates.
Project description:Localized T3 production modifies the transcriptome and promotes the hepatocyte-like lineage in iPSC-derived hepatic organoidslineage in iPSC-derived hepatic organoids
Project description:The generation of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) offers an unlimited source of patient-specific human cardiomyocytes. However, the use of iPSC-CM in vitro-models to guide the clinic selection of particular drugs for individual patients remains a vision. A major limitation represents the immature phenotype of iPSC-CMs, which alters their sensitivity towards physiological and pathophysiological stimuli, cardioactive drugs or toxic substances, in comparison to adult cardiomyocytes (CMs). In this study, we aim to generate iPSC-CMs with an advanced maturation state by combining the use of MM with the alignment of the cells on nanopatterned surfaces (NP) and induction of an increased contractile workload by electrical stimulation (ES). Under the combined influence of MM, NP and ES, iPSC-CMs develop a more complex cellular structure, increased mitochondrial content and enhanced electrophysiological properties. Furthermore, the response of iPSC-CMs matured under influence of MM, NP and ES to isoprenaline as well as verapamil differs to less mature iPSC-CMs cultured in B27-medium. Taken together, our results reveal that the combination of MM, NP and ES strongly improves the maturation state of iPSC-CMs and that this advanced maturation state critically affects the cell behavior in functional studies as well as response to cardioactive drugs.
Project description:To investigate the role of THRβ1 action in human iPSC-derived hepatocytes. We then performed gene expression profiling analysis using data obtained from RNA-seq of WT and THRBKO human iPSCs-derived hepatocytes in presence and absence of T3.
Project description:The immaturity of human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) is a major limitation for their use in drug screening to identify pro-arrhythmogenic or cardiotoxic molecules. Here, we demonstrate an approach that combines lipid-enriched maturation medium with a high concentration of calcium, nanopatterning of culture surfaces and electrostimulation to generate iPSC-CMs with advanced electrophysiological, structural and metabolic phenotypes. Systematic testing reveals that electrostimulation is the key driver of enhanced mitochondrial development and metabolic maturation and improved electrophysiological properties of iPSC-CMs. Increased calcium concentration strongly promotes electrophysiological maturation, while nanopatterning primarily facilitates sarcomere organisation with minor effect on electrophysiological properties. Transcriptome analysis reveals that activation of HMCES and TFAM targets contributes to mitochondrial development, whereas downregulation of MAPK/PI3K and SRF targets is associated with iPSC-CM polyploidy. These findings provide mechanistic insights into iPSC-CM maturation, paving the way for pharmacological responses that more closely resemble those of adult CMs.
Project description:To understand the role of MEF2A in iPSC-CMs maturation, we used MEF2A-siRNA to reduce MEF2A transcription in iPSC-CMs and then examined the changes in transcription levels
Project description:Direct contact between iPSC-derived macrophages and hepatocytes drives reciprocal acquisition of Kupffer cell identity and hepatocyte maturation