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Human pluripotent stem cells (hPSCs) are conventionally maintained on mouse embryonic fibroblast (MEF) feeder layers. However, downstream applications, such as directed differentiation protocols, are primarily optimized for feeder-free cultures. Therefore, hPSCs must often be adapted to feeder-free conditions. Here we propose a novel feeder-free adaptation protocol using StemFlex medium, which can be directly applied to thawed hPSC lines.The direct feeder-free adaptation protocol using StemFlex culture medium on Geltrex coating led to robust hPSC cultures in approximately 2 weeks. This approach was tested with three human embryonic stem cell (hESC) lines. All lines were confirmed to be pluripotent, expressing POU5F1, SOX2, and NANOG. No chromosomal imbalances were induced by the feeder-free adaptation.StemFlex medium enabled the efficient adaptation of hPSCs to feeder-free conditions directly after thawing. This protocol is easy to implement in laboratories that perform feeder-free cultures, allowing more convenient adaptation and more robust expansion of cryopreserved hPSCs, even in cases when sample quality is low or unknown.

Cells have a remarkable ability to self-organize and rearrange in functional organoids, this process was greatly boosted by the recent advances in 3D culture technologies and materials. Presently, this approach can be applied to model human organ development and function "in a dish" and can be used to predict drug response in a patient specific fashion.Here we describe a protocol that allows for the derivation of functional cardiac mini organoids consisting of cocultured cardiomyocytes and cardiac fibroblast. Cells are suspended in a drop of medium and encapsulated with hydrophobic fumed silica powder nanoparticles. These nanoparticles are treated with hydrophobic chemicals, hexamethyldisilazane (nHMDS), and result in the formation of microbioreactors. These microenvironments are defined as "liquid marbles," stimulating cell coalescence and 3D aggregation. Then nHMDS shell ensures optimal gas exchange between the interior liquid and the surrounding environment. This microbioreactor makes working in smaller volumes possible and is therefore amenable for higher throughput applications. Moreover, the properties of liquid marble microbioreactors makes it an excellent culture technique for cocultures. Here we demonstrate how cocultures of cardiac fibroblast and cardiomyocytes in a cardiosphere can be a valuable tool to model cardiac diseases in vitro and to assess cell interactions to decipher disease mechanisms.

Cells have a remarkable ability to self-organize and rearrange in functional organoids, this process was greatly boosted by the recent advances in 3D culture technologies and materials. Presently, this approach can be applied to model human organ development and function "in a dish" and can be used to predict drug response in a patient specific fashion.Here we describe a protocol that allows for the derivation of functional cardiac mini organoids consisting of cocultured cardiomyocytes and cardiac fibroblast. Cells are suspended in a drop of medium and encapsulated with hydrophobic fumed silica powder nanoparticles. These nanoparticles are treated with hydrophobic chemicals, hexamethyldisilazane (nHMDS), and result in the formation of microbioreactors. These microenvironments are defined as "liquid marbles," stimulating cell coalescence and 3D aggregation. Then nHMDS shell ensures optimal gas exchange between the interior liquid and the surrounding environment. This microbioreactor makes working in smaller volumes possible and is therefore amenable for higher throughput applications. Moreover, the properties of liquid marble microbioreactors makes it an excellent culture technique for cocultures. Here we demonstrate how cocultures of cardiac fibroblast and cardiomyocytes in a cardiosphere can be a valuable tool to model cardiac diseases in vitro and to assess cell interactions to decipher disease mechanisms.

Marfan syndrome (MFS) is a systemic disorder of connective tissue caused by pathogenic variants in the fibrillin-1 (FBN1) gene. Myocardial dysfunction has been demonstrated in MFS patients and mouse models, but little is known about the intrinsic effect on the cardiomyocytes (CMs). In this study, both induced pluripotent stem cells derived from a MFS-patient and the line with the corrected FBN1 mutation were differentiated to CMs. Several functional analyses are performed on this model to study MFS related cardiomyopathy. Atomic force microscopy revealed that MFS CMs are stiffer compared to corrected CMs. The contraction amplitude of MFS CMs is decreased compared to corrected CMs. Under normal culture conditions, MFS CMs show a lower beat-to-beat variability compared to corrected CMs using multi electrode array. Isoproterenol-induced stress or cyclic strain demonstrates lack of support from the matrix in MFS CMs. This study reports the first cardiac cell culture model for MFS, revealing abnormalities in the behavior of MFS CMs that are related to matrix defects. Based on these results, we postulate that impaired support from the extracellular environment plays a key role in the improper functioning of CMs in MFS.

Despite substantial literature on the dyeing of textiles, there is a lack of research about colouring Japanese mending papers (tissue papers) used for paper conservation purposes. This study investigates the fungal bioreceptivity of Japanese tissue papers after they have been treated with various dyes and pigments. A variety of toning materials including plant dyes, watercolours, acrylic paints, inks, pastels, gouaches, and colour pencils are commonly used by conservators for paper toning purposes. In this study, two Japanese tissue papers (Yukyu-shi and Sekishu Mare) were treated with selected plant dyes, watercolours, and acrylic paints and then inoculated with fungal species. Quantitative real-time polymerase chain reaction (qPCR) was used to quantify the DNA from Aspergillus niger and Penicillium rubrum as a proxy for fungal species abundance before and after inoculation and artificial moist heat ageing. qPCR primers which were universal for fungi amplified DNA from papers inoculated with A. niger and...

In previous publications, we described the population incidence of abnormalities in zebrafish larvae exposed to toxicants. Here, we examine the phenomenon of clustering or co-occurrence of abnormalities in individual larva. Our aim is to see how this clustering can be used to assess the specificity and severity of teratogenic effect. A total of 11,214 surviving larvae, exposed continuously from 1 day postfertilization (dpf) to one of 60 toxicants, were scored at 5 dpf for the presence of eight different abnormal phenotypes. These were as follows: pericardial edema, yolk sac edema, dispersed melanocytes, bent tail, bent trunk, hypoplasia of Meckel's cartilage, hypoplasia of branchial arches, and uninflated swim bladder. For 43/60 compounds tested, there was a concentration-dependent increase in the severity score (number of different abnormalities per larva). Statistical analysis showed that abnormalities tended to cluster (i.e., to occur in the same larva) more often than expected by chance alone. Yolk sac edema and dispersed melanocytes show a relatively strong association with one another and were typically the first abnormalities to appear in single larvae as the concentration of compound was increased. By contrast, hypoplastic branchial arches and hypoplastic Meckel's cartilage were only frequently observed in the most severely affected larvae. We developed a metric of teratogenicity (TC3/8), which represents the concentration of a compound that produces, on average, 3/8 abnormalities per larva. On this basis, the most teratogenic compounds tested here are amitriptyline, chlorpromazine hydrochloride, and sodium dodecyl sulfate; the least teratogenic is ethanol. We find a strong correlation between TC3/8 and LC50 of the 43 compounds that showed teratogenic effects. When we examined the ratio of TC3/8 to LC50, benserazide hydrochloride, copper (II) nitrate trihydrate, and nicotine had the highest specific teratogenicity, while aconitine, hesperidin, and ouabain octahydrate had the lowest. We conclude that analyzing the clustering of abnormalities per larva can provide an enriched teratogenic dataset compared with simple measurement of the population frequency of abnormalities.

The zebrafish larva is a promising whole-animal model for safety pharmacology, environmental risk assessment, and developmental toxicity. This model has been used for the high-throughput toxicity screening of various compounds. Our aim here is to identify possible phenotypic markers of teratogenicity in zebrafish embryos that could be used for the assaying compounds for reproductive toxicity. We have screened a panel of 60 water-soluble toxicants to examine their effects on zebrafish development. A total of 22,080 wild-type zebrafish larvae were raised in 250 μL defined buffer in 96-well plates at a plating density of one embryo per well. They were exposed for a 96-h period starting at 24 h post-fertilization. A logarithmic concentration series was used for range-finding, followed by a narrower geometric series for developmental toxicity assessment. A total of 9017 survivors were analyzed at 5 days post-fertilization for nine phenotypes, namely, (1) normal, (2) pericardial oedema, (3) yolk sac oedema, (4) melanophores dispersed, (5) bent tail tip, (6) bent body axis, (7) abnormal Meckel's cartilage, (8) abnormal branchial arches, and (9) uninflated swim bladder. For each toxicant, the EC50 (concentration required to produce one or more of these abnormalities in 50% of embryos) was also calculated. For the majority of toxicants (55/60) there was, at the population level, a statistically significant, concentration-dependent increase in the incidence of abnormal phenotypes among survivors. The commonest abnormalities were pericardial oedema, yolk sac oedema, dispersed melanophores, and uninflated swim bladder. It is possible therefore that these could prove to be general indicators of reproductive toxicity in the zebrafish embryo assay.