Polycomb-mediated silencing of miR-8 is required for maintenance of intestinal stemness in Drosophila melanogaster.

Balancing maintenance of self-renewal and differentiation is a key property of adult stem cells. The epigenetic mechanisms controlling this balance remain largely unknown. Herein, we report that the Polycomb Repressive Complex 2 (PRC2) is required for maintenance of the intestinal stem cell (ISC) pool in the adult female Drosophila melanogaster. We show that loss of PRC2 activity in ISCs by RNAi-mediated knockdown or genetic ablation of the enzymatic subunit Enhancer of zeste, E(z), results in loss of stemness and precocious differentiation of enteroblasts to enterocytes. Mechanistically, we have identified the microRNA miR-8 as a critical target of E(z)/PRC2-mediated tri-methylation of histone H3 at Lys27 (H3K27me3) and uncovered a dynamic relationship between E(z), miR-8 and Notch signaling in controlling stemness versus differentiation of ISCs. Collectively, these findings uncover a hitherto unrecognized epigenetic layer in the regulation of stem cell specification that safeguards intestinal homeostasis.

Use of Serum Protein Measurements as Biomarkers that Can Predict the Outcome of Diabetic Foot Ulceration.

Objectives: To identify proteins that are prognostic for diabetic foot ulcer (DFU) healing and may serve as biomarkers for its management, serum samples were analyzed from diabetic mellitus (DM) patients. Approach: The serum specimens that were evaluated in this study were obtained from DM patients with DFU who participated in a prospective study and were seen biweekly until they healed their ulcer or the exit visit at 12 weeks. The group was divided into Healers (who healed their DFU during the study) and Non-Healers. Results: Interleukin (IL)-10, IL-4, IL-5, IL-6, and IL-13 and interferon-gamma were higher in the Healers while Fractalkine, IL-8, and TNFα were higher in the Non-Healers. The trajectory of IL-10 levels remained stable over time within and across groups, resulting in a strong prognostic ability for the prospective DFU healing course. Classification and Regression Tree analysis created an 11-node decision tree with healing status as the categorical response. Innovation: Consecutive measurements of proteins associated with wound healing can identify biomarkers that can predict DFU healing over a 12-week period. IL-10 was the strongest candidate for prediction. Conclusion: Measurement of serum proteins can serve as a successful strategy in guiding clinical management of DFU. The data also indicate likely superior performance of building a multiprotein biomarker score instead of relying on single biomarkers.

A single-nucleus and spatial transcriptomic atlas of the COVID-19 liver reveals topological, functional, and regenerative organ disruption in patients.

The molecular underpinnings of organ dysfunction in acute COVID-19 and its potential long-term sequelae are under intense investigation. To shed light on these in the context of liver function, we performed single-nucleus RNA-seq and spatial transcriptomic profiling of livers from 17 COVID-19 decedents. We identified hepatocytes positive for SARS-CoV-2 RNA with an expression phenotype resembling infected lung epithelial cells. Integrated analysis and comparisons with healthy controls revealed extensive changes in the cellular composition and expression states in COVID-19 liver, reflecting hepatocellular injury, ductular reaction, pathologic vascular expansion, and fibrogenesis. We also observed Kupffer cell proliferation and erythrocyte progenitors for the first time in a human liver single-cell atlas, resembling similar responses in liver injury in mice and in sepsis, respectively. Despite the absence of a clinical acute liver injury phenotype, endothelial cell composition was dramatically impacted in COVID-19, concomitantly with extensive alterations and profibrogenic activation of reactive cholangiocytes and mesenchymal cells. Our atlas provides novel insights into liver physiology and pathology in COVID-19 and forms a foundational resource for its investigation and understanding.

A strain-programmed patch for the healing of diabetic wounds.

Diabetic foot ulcers and other chronic wounds with impaired healing can be treated with bioengineered skin or with growth factors. However, most patients do not benefit from these treatments. Here we report the development and preclinical therapeutic performance of a strain-programmed patch that rapidly and robustly adheres to diabetic wounds, and promotes wound closure and re-epithelialization. The patch consists of a dried adhesive layer of crosslinked polymer networks bound to a pre-stretched hydrophilic elastomer backing, and implements a hydration-based shape-memory mechanism to mechanically contract diabetic wounds in a programmable manner on the basis of analytical and finite-element modelling. In mouse and human skin, and in mini-pigs and humanized mice, the patch enhanced the healing of diabetic wounds by promoting faster re-epithelialization and angiogenesis, and the enrichment of fibroblast populations with a pro-regenerative phenotype. Strain-programmed patches might also be effective for the treatment of other forms of acute and chronic wounds.