Search

Traditional synthetic covalent hydrogels lack the native tissue dynamics and hierarchical fibrous structure found in the extracellular matrix (ECM). These dynamics and fibrous nanostructures are imperative in obtaining the correct cell/material interactions. Consequently, the challenge to engineer functional dynamics in a fibrous hydrogel and recapitulate native ECM properties remains a bottle-neck to biomimetic hydrogel environments. Here, the molecular tuning of a supramolecular benzene-1,3,5-tricarboxamide (BTA) hydrogelator via simple modulation of hydrophobic substituents is reported. This tuning results in fibrous hydrogels with accessible viscoelasticity over 5 orders of magnitude, while maintaining a constant equilibrium storage modulus. BTA hydrogelators are created with systematic variations in the number of hydrophobic carbon atoms, and this is observed to control the viscoelasticity and stress-relaxation timescales in a logarithmic fashion. Some of these BTA hydrogels are shear-thinning, self-healing, extrudable, and injectable, and can be 3D printed into multiple layers. These hydrogels show high cell viability for chondrocytes and human mesenchymal stem cells, establishing their use in tissue engineering applications. This simple molecular tuning by changing hydrophobicity (with just a few carbon atoms) provides precise control over the viscoelasticity and 3D printability in fibrillar hydrogels and can be ported onto other 1D self-assembling structures. The molecular control and design of hydrogel network dynamics can push the field of supramolecular chemistry toward the design of new ECM-mimicking hydrogelators for numerous cell-culture and tissue-engineering applications and give access toward highly biomimetic bioinks for bioprinting.

Stem cell (SC)-based therapies hold the potential to revolutionize therapeutics by enhancing the body's natural repair processes. Currently, there are only three SC therapies with marketing authorization within the European Union. To optimize outcomes, it is important to understand the biodistribution and behavior of transplanted SCs in vivo. A variety of imaging agents have been developed to trace SCs; however, they mostly lack the ability to simultaneously monitor the SC function and biodistribution at high resolutions. Here, we report the synthesis and application of a nanoparticle (NP) construct consisting of a gold NP core coated with rhodamine B isothiocyanate (RITC)-doped mesoporous silica (AuMS). The MS layer further contained a thiol-modified internal surface and an amine-modified external surface for dye conjugation. Highly fluorescent AuMS of three different sizes were successfully synthesized. The NPs were non-toxic and efficiently taken up by limbal epithelial SCs (LESCs). We further showed that we can functionalize AuMS with a reactive oxygen species (ROS)-sensitive fluorescent dye using two methods, loading the probe into the mesopores, with or without additional capping by a lipid bilayer, and by covalent attachment to surface and/or mesoporous-functionalized thiol groups. All four formulations displayed a ROS concentration-dependent increase in fluorescence. Further, in an ex vivo SC transplantation model, a combination of optical coherence tomography and fluorescence microscopy was used to synergistically identify AuMS-labeled LESC distribution at micrometer resolution. Our AuMS constructs allow for multimodal imaging and simultaneous ROS sensing of SCs and represent a promising tool for in vivo SC tracing.

Induced pluripotent stem cell (iPSC)–derived kidney organoids have the potential for a large variety of applications. However, they do not persist long in culture, for which reasons are still unclear. Furthermore, their morphological maturation, an essential feature for kidney function, has not been sufficiently assessed. Kidney organoids are transcriptionally much alike end-of-first-trimester fetal kidneys and present many of the same cell types. From large transmission electron microscopy tilescans of specific regions of interest, we compared the ultrastructures of iPSC-derived kidney organoids at various timepoints to human fetal kidneys of the first trimester. Unlike healthy fetal kidneys, large glycogen deposits developed over time in all organoid cell types, but particularly in podocytes and in chondrocytes, one of the off-target populations that contaminate the culture. Deeper investigation showed that glycogen synthase kinase 3b (GSK3β) levels and activation were diminished over time, correlated with the accumulation of glycogen. Activated YAP was strongly expressed and large lipid droplets accumulated over time in proximal tubules. Accordingly, EGFR signaling increased significantly over time. Mitochondria in glomeruli and tubules contained few or no cristae, indicating mitochondrial damage. Together these features are known for hyperglycemic cultures and diabetic nephropathy. Measuring the glucose concentration in the kidney organoid culture medium showed a concentration of 2.94 g/mL, which is considered an elevated, pre-diabetic–like concentrationin vitro. In summary, our ultrastructural assessment of iPSC-derived kidney organoids using an age-matched fetal human reference allowed the evaluation of cellular morphology, and we identified intracellular features that can inform the cellular state, which is particularly important while physiological testing of organoids is limited.Translational StatementKidney organoids hold promise as a future treatment for patients with end-stage kidney disease. The engineering of kidney organoids with correct and healthy morphologyin vitrois therefore essential, to guarantee functionality after transplantation. The present study provided deeper insights into the structural organization and ultrastructure of cells in kidney organoids compared to age-matched human fetal kidneys. Accordingly, we found several features in the regular kidney organoid culture, which are known to occur in hyperglycemic cultures and diabetic nephropathy, indicating that the current medium composition may be inducing pathological cellular phenotypes. This study therefore creates a better understanding of current limitations in the kidney organoid culture, increases knowledge of their function and cellular organization, and sets the foundation for further research to create advanced organoids.

Research on the ultrastructural development of the kidney is limited, and research on rodent kidneys prevails. Yet, large differences between rodent and human nephrogenesis exist and therefore translation between species is not desirable. At the same time, there is an increasing demand for human research, in addition to assessing the potential of novel therapies such as renal organoids. We therefore generated an interactive atlas of large transmission electron microscopy tile scans of first trimester human kidneys, specifically Carnegie stage 20 until post-conceptional week 12. Analysis identified key ultrastructural features of proximal and distal progenitor cells such as cell shape, microvilli and luminal budding in the renal vesicle. Regarding glomerular development, we identified a new W-shaped body stage and three distinct sub-stages of the well-known capillary loop stage. Chromatin organization, nuclear shape and location were used to describe tubule cell identity and maturity, indicating a specific order of tubular maturation. The greatest congruence with adult tissue was seen in proximal tubules and the least in distal tubules. Finally, cytoplasmic glycogen depositions in collecting duct cells, which are absent in adult tissue, were found to be an early feature distinguishing distal tubules from collecting ducts as well as differentiating cortical from medullary collecting ducts. The findings of this research provide new fundamental insights for researchers who aim to understand and recreate kidney development.

Microscopy has revolutionised our view on biology and has been vital for many discoveries since its invention around 200 years ago. Recent developments in cell biology have led to a strong interest in generating spheroids and organoids that better represent tissue. However, the current challenge faced by many researchers is the culture and analysis of these three-dimensional (3D) cell cultures. With the technological improvements in reconstructing volumetric datasets by optical sections, it is possible to quantify cells, their spatial arrangement, and the protein distribution without destroying the physical organization. We assessed three different microwell culture plates and four analysis tools for 3D imaging data for their applicability for the analysis of 3D cultures. A key advantage of microwell plates is their potential to perform high-throughput experiments in which cell cultures are generated and analysed in one single system. However, it was shown that this potential could be impacted by the material composition and microwell structure. For example, antibody staining was not possible in a hydrogel microwell, and truncated pyramid–structured microwells had increased background fluorescence due to their structure. Regarding analysis tools, four different software, namely CellProfiler, Fiji/ImageJ, Nikon GA3 and Imaris, were compared for their accuracy and applicability in analysing datasets from 3D cultures. The results showed that the open-access software, CellProfiler and Fiji, could quantify nuclei and cells, yet with varying results compared to manual counting, and may require post-processing optimisation. On the other hand, the GA3 and Imaris software packages showed excellent versatility in usage and accuracy in the quantification of nuclei and cells, and could classify cell localisation. Together these results provide critical considerations for microscopic imaging and analysis of 3D cell cultures.

The article reports results from a Human Early Learning Partnership initiative that aims to address limitations within the literature concerning neighborhood effects on child development. Problems include the tendency for studies to (a) rely on small samples of children, (b) focus on high-risk populations, (c) define neighborhood by Census boundaries, (d) attend only to 1 or 2 developmental domains, and (e) adhere to a narrow understanding of socioeconomic status. By collecting data from a near-census of kindergarten children in British Columbia, Canada, using the Early Development Instrument, our research addresses all 5 problems. Findings reported in this article lay the groundwork for the Human Early Learning Partnership's much more ambitious program of social care research that aims to measure directly the processes by which physical and social settings influence human development in the formative early years, rather than to infer them from data routinely collected for other purposes. The article conc...

In the current research project, the relationship between neighborhood environment and school readiness was investigated. To measure neighbourhood environment, data from the 2001 Canadian Census were used, while school readiness was measured using the Early Development Instrument (EDI). EDI data were collected for kindergarten children across British Columbia, Canada, in the school years 2000/2001 through 2004/2005 by the Human Early Learning Partnership. A hierarchical linear modeling approach to data analysis was taken given the complex structure of the data (children nested within neighborhoods). Results from this study suggest that neighborhood environment is related to children's school readiness outcomes as measured by the EDI. Specifically, all 5 EDI domains were significantly predicted by between 2 and 8 of 13 neighborhood variables that were conceptually grouped into 8 categories accounting for family structure, income, education, Aboriginal status, language, labor force occupations, employment r...

This paper reports results of an exploratory study examining factors that might be associated with achievement in mathematics and participation in advanced mathematics courses in Canada, Norway, and the United States of America (USA). These factors, which were not directly related to schooling accounted for large degrees of variability, 24% to 39%, in mathematics achievement scores. Confidence in mathematics was the strongest predictor of achievement for students from Canada and Norway, whereas for the students from the USA, parents' highest education level was the highest predictor of achievement. Student home environment related variables were stronger predictors of achievement for females than for males in all three countries. The participation in advanced mathematics courses could be predicted with 72% to 76% accuracy by the same variables. In all of the three countries, the strongest predictors of participation in advanced mathematics courses were students' attitudes toward mathematics. Parents' education level, a socioeconomic related variable, was one of the strongest predictors of participation for Canadian female students and all students from the USA.

This experiment investigates the development of performance expectations in status-homogeneous task groups. The issue of central interest is whether or not gender is a factor in expectation formation when group members are of the same sex and work on a gender-neutral task. Male and female undergraduates, participating in same-sex dyads, worked first individually and then as a team on a novel, visual perception task. Apart from the feedback they received from the experimenter at the end of the individual performance phase, participants were given no information with which to form differentiated expectations about self and partner for this task We investigate effects from both sex of dyad and level of feedback on: (a) influence behavior during the team phase, and (b) selected variables obtained through self-reports. Rejection of influence data show statistically significant effects from feedback only. Self-reports, on the other hand, reveal significant results from both feedback and sex of subject across several assessments of self's and partner's competence, and from sex of subject in some of the items concerning perceptions of the experimenter's status. Different conditions for the emergence of such effects in behaviors as opposed to self-reports are identified and discussed.

This article concerns the logic and empirical assessment of conditional hypotheses; as an example, we examine gender as status. A variety of expectation states hypotheses on gender effects in task groups assume that gender is a status characteristic for the group members. We report on an experiment designed as a check of whether the participants meet that assumption and, if so, to what extent. Subjects were male and female undergraduates assigned to work with either a male or a female partner on a novel perceptual task. We collected behavioral data on rejection of influence from the partner, and self-reports on perceptions of the task situation. Results show no significant differences across conditions in influence rejection, and only a few such differences in the self-reports. After reviewing possible alternative interpretations of the results, we conclude that gender was not a status characteristic in this case. Other implications ofthe findings are also examined.