Background The ongoing COVID-19 pandemic postponed routine follow-up visits of many orthodontic patients, which compromised their treatment process and mental states. This study was aimed to assess orthodontic emergency occurrence and psychological states of Chinese orthodontic patients during this pandemic. Methods Orthodontic patients in China were invited to answer an anonymous online questionnaire from February 20, 2020 to March 5, 2020, when routine dental care was suspended in China. The questionnaire included self-assessment of oral hygiene and compliance, orthodontic emergencies, perceptions and feelings about COVID-19 and anxiety self-rating scale, etc. Collected data was statistically analyzed with Chi-square, independent t test and univariable generalized estimating equations regression analysis. Results A total of 1078 respondents (292 male; 786 female) from 30 provinces of China were included in this study. About one-third (33.67%) of patients reported that they encountered orthodontic problems during the pandemic. Patients with clear aligners reported fewer orthodontic problems than those with fixed appliances or removable appliances. Female patients, elder patients and patients who encountered orthodontic emergencies were more anxious than other patients. Conclusions The compliance and occurrence of orthodontic emergencies differed in patients with different orthodontic appliances. Patients with orthodontic emergencies exhibited higher anxiety states.

For stem cell research, three‐dimensional (3D) hydrogels are increasingly recognized as more physiological systems than two‐dimensional culture plates due to bidirectional and 3D interaction of stem cells and surrounding matrix. Among various stem cells, mesenchymal stem cells (MSCs) are one of the most widely applied from bench to bedside. In 3D hydrogels, MSCs are allowed to actively remodel the surrounding matrix through proteolytic degradation and cell‐exerted force, which highly resembles in vivo situation. Notably, factors affecting hydrogel modifiability including matrix viscoelasticity and matrix degradability have been found to regulate adhesion, morphology, and fate decision of MSCs. In addition, MSCs within 3D hydrogels have been found to employ multiple mechanotransduction mechanisms including not only the classic integrin–actomyosin cytoskeleton system but also ion channels, microtubule cytoskeleton, and self‐secreted proteinaceous matrix. This review summarizes the effects of biophysical cues on MSCs differentiation in 3D hydrogels and underlying mechanobiology in a hope to update our readers' understanding of stem cell biology and guide tissue engineering.

Backgrounds: Both matrix stiffness and cell morphology have been found as important factors directing MSCs (mesenchymal stem cells) differentiation, but cells also spontaneously adapt their morphology under matrix stiffness stimulation. This study aimed to investigate the interplay of cell morphology and matrix stiffness on osteogenesis and adipogenesis of rBMSCs(rat bone BMSCs) on 2D substrates.Methods and Results: First, we modulated MSCs morphology through different bronectin (FN) concentrations on tissue culture plates (TCPs). We found FN promoted and osteogenesis of BMSCs while suppressing adipogenesis, mediated by FN-induced F-actin polymerization and cell spreading. Based on these ndings, we modulated BMSCs morphology on 0.5 kPa and 32 kPa CytoSoft ® plates through FN concentrations. We found BMSCs on 0.5 kPa substrates coated with 300μg/ml of FN manifested similarly spreading morphology with cells on 32 kPa substrates coated with 100 μg/ml of FN, and cells in both groups dominantly commit osteogenesis. On the other hand, BMSCs on 32 kPa substrates coated with 30μg/ml of FN manifested similarly restricted morphology with cells in on 0.5 kPa substrates with 100μg/ml of FN, and in both groups cells mainly commit adipogenesis. Immuno uorescence staining indicated YAP/TAZ mainly located in cytoplasm when cells exhibited restricted morphology on stiff matrices, while exhibiting signi cant nuclear translocation when cells spread on soft matrices.Conclusions: Cell morphology overrode effects of matrix stiffness on BMSCs differentiation through more robust regulation of YAP/TAZ. Matrix stiffness depended on cell morphology to regulate osteogenesis and adipogenesis of BMSCs.