Preparation and Properties of Egg White Dual Cross-Linked Hydrogel with Potential Application for Bone Tissue Engineering

In this study, an egg white dual cross-linked hydrogel was developed based on the principle that the external stimulus can denature proteins and cause them to aggregate, forming hydrogel. The sodium hydroxide was used to induce gelation of the egg white protein, subsequently introducing calcium ions to cross-link with protein chains, thereby producing a dual cross-linked hydrogel. The characteristics of the dual cross-linked hydrogels—including the secondary structure, stability, microstructure, swelling performance, texture properties, and biosafety—were investigated to determine the effects of calcium ion on the egg white hydrogel (EWG) and evaluate the potential application in the field of tissue engineering. Results showed that calcium ions could change the β-sheet content of the protein in EWG after soaking it in different concentrations of CaCl2 solution, leading to changes in the hydrogen bonds and the secondary structure of polypeptide chains. It was confirmed that calcium ions promoted the secondary cross-linking of the protein chain, which facilitated polypeptide folding and aggregation, resulting in enhanced stability of the egg white dual cross-linked hydrogel. Furthermore, the swelling capacity of the EWG decreased with increasing concentration of calcium ions, and the texture properties including hardness, cohesiveness and springiness of the hydrogels were improved. In addition, the calcium cross-linked EWG hydrogels exhibited biocompatibility and cell-surface adhesion in vitro. Hence, this work develops a versatile strategy to fabricate dual cross-linked protein hydrogel with biosafety and cell-surface adhesion, and both the strategy and calcium-egg white cross-linked hydrogels have potential for use in bone tissue engineering

Yeast β‑Glucan Suppresses the Chronic Inflammation and Improves the Microenvironment in Adipose Tissues of ob/ob Mice

Inflammation in visceral adipose tissues (VATs) contributes to the pathology of diabetes. This study focused on the inflammatory regulation in VATs by a yeast β-1,3-glucan (BYG) orally administered to ob/ob mice. BYG decreased pro-inflammatory modulators of TNF-α, IL-6, IL-1β, CCL2, and <i>SAA3</i>, and increased anti-inflammatory factors of <i>Azgp1</i> (2.53 ± 0.02-fold change) at protein and/or mRNA levels (<i>p</i> < 0.05). Remarkably, BYG decreased the degree of adipose tissue macrophages (ATMs) infiltration to 82.5 ± 8.3%, especially the newly recruited ATMs. Interestingly, BYG increased the protective Th2 cell regulator <i>GATA3</i> (7.72 ± 0.04-fold change) and decreased immunosuppressors <i>IL-10</i> and IL-1ra, suggesting that BYG elicited inflammation inhibition via stimulating immune responses. Additionally, BYG increased the gut microbiota proportion of <i>Akkermansia</i> from 0.07% to 4.85% and improved the microenvironment of VATs through decreasing fibrosis and angiogenesis. These findings suggest that BYG has anti-inflammatory effect in diabetic mice, which can be used as a food component and/or therapeutic agent for diabetes