Hydrogel biomaterials that stiffen and soften on demand reveal that skeletal muscle stem cells harbor a mechanical memory.

Muscle stem cells (MuSCs) are specialized cells that reside in adult skeletal muscle poised to repair muscle tissue. The ability of MuSCs to regenerate damaged tissues declines markedly with aging and in diseases such as Duchenne muscular dystrophy, but the underlying causes of MuSC dysfunction remain poorly understood. Both aging and disease result in dramatic increases in the stiffness of the muscle tissue microenvironment from fibrosis. MuSCs are known to lose their regenerative potential if cultured on stiff plastic substrates. We sought to determine whether MuSCs harbor a memory of their past microenvironment and if it can be overcome. We tested MuSCs in situ using dynamic hydrogel biomaterials that soften or stiffen on demand in response to light and found that freshly isolated MuSCs develop a persistent memory of substrate stiffness characterized by loss of proliferative progenitors within the first three days of culture on stiff substrates. MuSCs cultured on soft hydrogels had altered cytoskeletal organization and activity of Rho and Rac guanosine triphosphate hydrolase (GTPase) and Yes-associated protein mechanotransduction pathways compared to those on stiff hydrogels. Pharmacologic inhibition identified RhoA activation as responsible for the mechanical memory phenotype, and single-cell RNA sequencing revealed a molecular signature of the mechanical memory. These studies highlight that microenvironmental stiffness regulates MuSC fate and leads to MuSC dysfunction that is not readily reversed by changing stiffness. Our results suggest that stiffness can be circumvented by targeting downstream signaling pathways to overcome stem cell dysfunction in aged and disease states with aberrant fibrotic tissue mechanics.

Protective effect of zinc gluconate on intestinal mucosal barrier injury in antibiotics and LPS-induced mice.

Objective: The aim of the study is to investigate the function and mechanism of Zinc Gluconate (ZG) on intestinal mucosal barrier damage in antibiotics and Lipopolysaccharide (LPS)-induced mice. Methods: We established a composite mouse model by inducing intestinal mucosal barrier damage using antibiotics and LPS. The animals were divided into five groups: Control (normal and model) and experimental (low, medium, and high-dose ZG treatments). We evaluated the intestinal mucosal barrier using various methods, including monitoring body weight and fecal changes, assessing pathological damage and ultrastructure of the mouse ileum, analyzing expression levels of tight junction (TJ)-related proteins and genes, confirming the TLR4/NF-κB signaling pathway, and examining the structure of the intestinal flora. Results: In mice, the dual induction of antibiotics and LPS led to weight loss, fecal abnormalities, disruption of ileocecal mucosal structure, increased intestinal barrier permeability, and disorganization of the microbiota structure. ZG restored body weight, alleviated diarrheal symptoms and pathological damage, and maintained the structural integrity of intestinal epithelial cells (IECs). Additionally, ZG reduced intestinal mucosal permeability by upregulating TJ-associated proteins (ZO-1, Occludin, Claudin-1, and JAM-A) and downregulating MLCK, thereby repairing intestinal mucosal barrier damage induced by dual induction of antibiotics and LPS. Moreover, ZG suppressed the TLR4/NF-κB signaling pathway, demonstrating anti-inflammatory properties and preserving barrier integrity. Furthermore, ZG restored gut microbiota diversity and richness, evidenced by increased Shannon and Observed features indices, and decreased Simpson's index. ZG also modulated the relative abundance of beneficial human gut bacteria (Bacteroidetes, Firmicutes, Verrucomicrobia, Parabacteroides, Lactobacillus, and Akkermansia) and harmful bacteria (Proteobacteria and Enterobacter), repairing the damage induced by dual administration of antibiotics and LPS. Conclusion: ZG attenuates the dual induction of antibiotics and LPS-induced intestinal barrier damage and also protects the intestinal barrier function in mice.

Exploring the causal relationship: bidirectional mendelian randomization study on benign prostatic hyperplasia and cardiovascular diseases.

Background: Benign prostatic hyperplasia (BPH) is a common disease occurring in elderly and middle-aged men, and cardiovascular diseases (CVDs) are one of the major causes of death worldwide. Many observational studies examined have found a strong association between BPH and CVDs, but the causal relationship between them is unclear. The aim of this study was to determine the causal relationship between BPH and CVDs, specifically five diseases: stroke, coronary heart disease (CHD), heart failure, myocardial infarction (MI), and atrial fibrillation (AF). Methods: In this study, we obtained single nucleotide polymorphisms (SNPs) of patients with BPH from the UK Biobank database and patients with CVDs from the UK Biobank, the HERMES Consortium, and the FinnGen Genome Database, each used as a genetic tool for a Mendelian randomization (MR) study. We used conventional MR analysis to assess potential causal direction between BPH and CVDs, as well as MR-Egger, MR-PRESSO, model-based estimation (MBE) and weighted median methods for sensitivity analysis. Results: Using a bidirectional two-sample MR study, we found that BPH patients had an increased risk of developing CHD (ConMix OR = 1.152, 95% CI: 1.011-1.235, p = 0.035) and MI (ConMix OR = 1.107.95% CI: 1.022-1.164, p = 0.013), but a decreased risk of stroke (ConMix OR = 0.872, 95% CI: 0.797-0.926, p = 0.002). The reverse study was not statistically significant and further research may be needed. Conclusion: Our study suggests a potential causal relationship between BPH and CVDs. BPH appears to be a risk factor for CHD and MI, but it may be protective against stroke. There was no evidence of a causal association in the reverse study, and a larger sample size was needed in follow-up to further explore the potential association.