Development of a 3D atlas of the embryonic pancreas for topological and quantitative analysis of heterologous cell interactions.

Generating comprehensive image maps, while preserving spatial three-dimensional (3D) context, is essential in order to locate and assess quantitatively specific cellular features and cell-cell interactions during organ development. Despite recent advances in 3D imaging approaches, our current knowledge of the spatial organization of distinct cell types in the embryonic pancreatic tissue is still largely based on two-dimensional histological sections. Here, we present a light-sheet fluorescence microscopy approach to image the pancreas in three dimensions and map tissue interactions at key time points in the mouse embryo. We demonstrate the utility of the approach by providing volumetric data, 3D distribution of three main cellular components (epithelial, mesenchymal and endothelial cells) within the developing pancreas, and quantification of their relative cellular abundance within the tissue. Interestingly, our 3D images show that endocrine cells are constantly and increasingly in contact with endothelial cells forming small vessels, whereas the interactions with mesenchymal cells decrease over time. These findings suggest distinct cell-cell interaction requirements for early endocrine cell specification and late differentiation. Lastly, we combine our image data in an open-source online repository (referred to as the Pancreas Embryonic Cell Atlas).

Harnessing choice architecture in urologic practice: Implementation of an opioid-sparing protocol grounded in cognitive behavioral theory.

PURPOSE: Opioids are prescribed excessively following surgery. As many urologic oncology procedures are performed minimally invasively, an opportunity exists to push forward initiatives to minimize postoperative opioid use. MATERIALS AND METHODS: A quality improvement initiative to reduce inpatient opioid prescribing was launched at a tertiary cancer center. In Phase I (December 2019-July 2020), providers were instructed to start standing acetaminophen. In Phase II (beginning August 2020), education was provided to the entire care team and ordersets were modified to an opioid sparing protocol (OSP). We analyzed the proportion of minimally invasive surgery (MIS) prostatectomy and nephrectomy patients that adhered to an OSP during each phase and compared them to controls from the preceding 2 years. RESULTS: A total of 303, 153, and 839 patients underwent MIS during the Phase I, Phase II, and control periods respectively. The proportion of patients adhering to an OSP increased from 16% at the beginning of Phase I to 76% at the end of Phase II (p-trend < 0.001). The median total oral morphine equivalents for oral opioids declined from 20 mg and 40 mg at baseline for prostatectomy and nephrectomy patients respectively to 0 mg for both groups (p-trends < 0.001). Multivariable analysis found that patients received 22% and 81% less oral morphine equivalents during Phase I and II respectively compared to the control period (P < 0.001). CONCLUSIONS: Adherence to an OSP is most effective when initiatives incorporate the entire team and are supported by nudge theory-based structural changes. Using these strategies, most patients following urologic MIS can dramatically reduce opioid use postoperatively.

The biomechanical basis of biased epithelial tube elongation in lung and kidney development.

During lung development, epithelial branches expand preferentially in a longitudinal direction. This bias in outgrowth has been linked to a bias in cell shape and in the cell division plane. How this bias arises is unknown. Here, we show that biased epithelial outgrowth occurs independent of the surrounding mesenchyme, of preferential turnover of the extracellular matrix at the bud tips and of FGF signalling. There is also no evidence for actin-rich filopodia at the bud tips. Rather, we find epithelial tubes to be collapsed during early lung and kidney development, and we observe fluid flow in the narrow tubes. By simulating the measured fluid flow inside segmented narrow epithelial tubes, we show that the shear stress levels on the apical surface are sufficient to explain the reported bias in cell shape and outgrowth. We use a cell-based vertex model to confirm that apical shear forces, unlike constricting forces, can give rise to both the observed bias in cell shapes and tube elongation. We conclude that shear stress may be a more general driver of biased tube elongation beyond its established role in angiogenesis. This article has an associated 'The people behind the papers' interview.

Image-based modeling of kidney branching morphogenesis reveals GDNF-RET based Turing-type mechanism and pattern-modulating WNT11 feedback.

Branching patterns and regulatory networks differ between branched organs. It has remained unclear whether a common regulatory mechanism exists and how organ-specific patterns can emerge. Of all previously proposed signalling-based mechanisms, only a ligand-receptor-based Turing mechanism based on FGF10 and SHH quantitatively recapitulates the lung branching patterns. We now show that a GDNF-dependent ligand-receptor-based Turing mechanism quantitatively recapitulates branching of cultured wildtype and mutant ureteric buds, and achieves similar branching patterns when directing domain outgrowth in silico. We further predict and confirm experimentally that the kidney-specific positive feedback between WNT11 and GDNF permits the dense packing of ureteric tips. We conclude that the ligand-receptor based Turing mechanism presents a common regulatory mechanism for lungs and kidneys, despite the differences in the molecular implementation. Given its flexibility and robustness, we expect that the ligand-receptor-based Turing mechanism constitutes a likely general mechanism to guide branching morphogenesis and other symmetry breaks during organogenesis.