Search

Cardiomyocytes (CMs) from human induced pluripotent stem cells (hiPSCs) are functionally immature, but this is improved by incorporation into engineered tissues or forced contraction. Here, we showed that tri-cellular combinations of hiPSC-derived CMs, cardiac fibroblasts (CFs), and cardiac endothelial cells also enhance maturation in easily constructed, scaffold-free, three-dimensional microtissues (MTs). hiPSC-CMs in MTs with CFs showed improved sarcomeric structures with T-tubules, enhanced contractility, and mitochondrial respiration and were electrophysiologically more mature than MTs without CFs. Interactions mediating maturation included coupling between hiPSC-CMs and CFs through connexin 43 (CX43) gap junctions and increased intracellular cyclic AMP (cAMP). Scaled production of thousands of hiPSC-MTs was highly reproducible across lines and differentiated cell batches. MTs containing healthy-control hiPSC-CMs but hiPSC-CFs from patients with arrhythmogenic cardiomyopathy strikingly recapitulated features of the disease. Our MT model is thus a simple and versatile platform for modeling multicellular cardiac diseases that will facilitate industry and academic engagement in high-throughput molecular screening.

Item does not contain fulltext, Animal models continue to be used to investigate cartilage repair strategies. Adequate anaesthesia and pain management are essential in order to guarantee acceptable animal welfare as well as reproducible experimental results. This systematic review evaluates reporting of anaesthesia and pain management in surgical large animal models (horse, pig, dog, goat and sheep) of (osteo)chondral repair. Manuscripts published between 2015 and 2020 were included after a comprehensive search strategy. Data were evaluated using descriptive statistics and qualitative review. Out of 223 eligible studies, 220 studies contained incomplete information on anaesthetic and pain management. Pre-, intra- and post-operative analgesia were not mentioned in 68%, 94%, and 64% of manuscripts respectively. A total of 176 studies reported that animals underwent general anaesthesia during surgery. Surprisingly, 30% of these articles did not provide any detail on anaesthetic management, while 37% reported using inhalant, hypnotic or sedative drugs only, without mention of analgesics. Pain monitoring was not reported in 87% of manuscripts. The vast majority of preclinical large animal studies on cartilage repair did not meet veterinary clinical standards for anaesthesia and analgesia, and failed to report according to the ARRIVE international guidelines. In light of serious welfare, ethical and translational validity concerns, improvement is urgently needed.

By their interaction with IgG immune complexes, FcgammaR and complement link innate and adaptive immunity, showing functional redundancy. In complement-deficient mice, IgG downstream effector functions are often impaired, as well as adaptive immunity. Based on a variety of model systems using FcgammaR-knockout mice, it has been concluded that FcgammaRs are also key regulators of innate and adaptive immunity; however, several of the model systems underpinning these conclusions suffer from flawed experimental design. To address this issue, we generated a novel mouse model deficient for all FcgammaRs (FcgammaRI/II/III/IV(-/-) mice). These mice displayed normal development and lymphoid and myeloid ontogeny. Although IgG effector pathways were impaired, adaptive immune responses to a variety of challenges, including bacterial infection and IgG immune complexes, were not. Like FcgammaRIIb-deficient mice, FcgammaRI/II/III/IV(-/-) mice developed higher Ab titers but no autoantibodies. These observations indicate a redundant role for activating FcgammaRs in the modulation of the adaptive immune response in vivo. We conclude that FcgammaRs are downstream IgG effector molecules with a restricted role in the ontogeny and maintenance of the immune system, as well as the regulation of adaptive immunity.

Naive mouse embryonic stem cells (mESCs) are in a metastable state and fluctuate between inner cell mass-and epiblast-like phenotypes. Here, we show transient activation of the BMP-SMAD signaling pathway in mESCs containing a BMP-SMAD responsive reporter transgene. Activation of the BMP-SMAD reporter transgene in naive mESCs correlated with lower levels of genomic DNA methylation, high expression of 5-methylcytosine hydroxylases Tet1/2 and low levels of DNA methyltransferases Dnmt3a/b. Moreover, naive mESCs, in which the BMP-SMAD reporter transgene was activated, showed higher resistance to differentiation. Using double Smad1; Smad5 knockout mESCs, we showed that BMP-SMAD signaling is dispensable for self-renewal in both naive and ground state. These mutant mESCs were still pluripotent, but they exhibited higher levels of DNA methylation than their wild-type counterparts and had a higher propensity to differentiate. We showed that BMP-SMAD signaling modulates lineage priming in mESCs, by transiently regulating the enzymatic machinery responsible for DNA methylation.

Item does not contain fulltext, Gastrointestinal tumor growth is thought to be promoted by gastrointestinal bacteria and their inflammatory products. We observed that intestine-specific conditional Apc mutant mice (FabplCre;Apc (15lox/+)) developed many more colorectal tumors under conventional than under pathogen-low housing conditions. Shotgun metagenomic sequencing plus quantitative PCR analysis of feces DNA revealed the presence of two bacterial species in conventional mice, absent from pathogen-low mice. One, Helicobacter typhlonius, has not been associated with cancer in man, nor in immune-competent mice. The other species, mucin-degrading Akkermansia muciniphila, is abundantly present in healthy humans, but reduced in patients with inflammatory gastrointestinal diseases and in obese and type 2 diabetic mice. Eradication of H.typhlonius in young conventional mice by antibiotics decreased the number of intestinal tumors. Additional presence of A.muciniphila prior to the antibiotic treatment reduced the tumor number even further. Colonization of pathogen-low FabplCre;Apc (15lox/+) mice with H.typhlonius or A.muciniphila increased the number of intestinal tumors, the thickness of the intestinal mucus layer and A.muciniphila colonization without H.typhlonius increased the density of mucin-producing goblet cells. However, dual colonization with H.typhlonius and A.muciniphila significantly reduced the number of intestinal tumors, the mucus layer thickness and goblet cell density to that of control mice. By global microbiota composition analysis, we found a positive association of A.muciniphila, and of H.typhlonius, and a negative association of unclassified Clostridiales with increased tumor burden. We conclude that A.muciniphila and H.typhlonius can modulate gut microbiota composition and intestinal tumor development in mice.

Contains fulltext : 118107.pdf (Publisher’s version ) (Open Access), Caspase-1 is known to activate the proinflammatory cytokines IL-1beta and IL-18. Additionally, it can cleave other substrates, including proteins involved in metabolism. Recently, we showed that caspase-1 deficiency in mice strongly reduces high-fat diet-induced weight gain, at least partly caused by an increased energy production. Increased feces secretion by caspase-1-deficient mice suggests that lipid malabsorption possibly further reduces adipose tissue mass. In this study we investigated whether caspase-1 plays a role in triglyceride-(TG)-rich lipoprotein metabolism using caspase-1-deficient and wild-type mice. Caspase-1 deficiency reduced the postprandial TG response to an oral lipid load, whereas TG-derived fatty acid (FA) uptake by peripheral tissues was not affected, demonstrated by unaltered kinetics of [(3)H]TG-labeled very low-density lipoprotein (VLDL)-like emulsion particles. An oral gavage of [(3)H]TG-containing olive oil revealed that caspase-1 deficiency reduced TG absorption and subsequent uptake of TG-derived FA in liver, muscle, and adipose tissue. Similarly, despite an elevated hepatic TG content, caspase-1 deficiency reduced hepatic VLDL-TG production. Intestinal and hepatic gene expression analysis revealed that caspase-1 deficiency did not affect FA oxidation or FA uptake but rather reduced intracellular FA transport, thereby limiting lipid availability for the assembly and secretion of TG-rich lipoproteins. The current study reveals a novel function for caspase-1, or caspase-1-cleaved substrates, in controlling intestinal TG absorption and hepatic TG secretion.