Osteoarthritis (OA) is a degenerative illness that greatly impacts the life quality of patients. Currently, the therapeutic approaches for OA are very limited in clinical. The extracellular vesicles (EVs) derived from different mesenchymal stem cells displayed a prominent therapeutic effect on OA. But most EVs have limited resources and the risks of host rejection, immunological response, and etc. Human umbilical cord mesenchymal stem cells (hUCMSCs) hold the advantages of easy availability, minimal immune rejection, and excellent immunomodulatory effects, although hUCMSCs-EVs have seldom been applied in OA. Herein, we investigated the potential immunomodulatory and anti-inflammatory effects of hUCMSCs-EVs on the treatment of OA. In our results, the treatment of hUCMSCs-EVs promoted the polarization of M2-type macrophages and the expression of anti-inflammation-related cytokines (IL-10). Notably, the supernate of M2 macrophages induced by hUCMSCs-EVs inhibited the level of inflammation-associated factors in OA chondrocytes caused by IL-1β. Further, injection of hUCMSCs-EVs in the articular lumen ameliorated progression of OA and exerted chondroprotective potential based on the OA joint model created by the surgical transection of the anterior cruciate ligament (ACLT). In addition, we found five highly enriched miRNAs in hUCMSCs-EVs, including has-miR-122-5p, has-miR-148a-3p, has-miR-486-5p, has-miR-let-7a-5p, and has-miR-100-5p by High-throughput sequencing of miRNAs, with targeted genes mainly enriched in the PI3K-Akt signaling pathway. Furthermore, we also detected the protein abundance of hUCMSCs-EVs using liquidation chromatography with tandem quadrupole mass spectrometry (LC–MS/MS) analysis. Thus, our study indicates that hUCMSCs-EVs can alleviate cartilage degradation during the OA progression, mechanically may through delivering key proteins and modulating the PI3K-Akt signaling pathway mediated by miRNAs to promote polarization of M2 macrophage, exhibiting potent immunomodulatory potential. The current findings suggest that hUCMSCs-EVs might serve as a new reagent for the therapy of OA. Graphical Abstract

BackgroundHepatitis B e Antigen (HBeAg)-negative chronic hepatitis B (CHB) patients have an active liver disease with a high risk of progression to decompensated cirrhosis and hepatocellular carcinoma. The management strategy for HBeAg-negative CHB patients treated with nucleos(t)ide analogues (NUCs) is a topic of concern. To observe the outcomes for this population after NUCs withdrawal, HBeAg-negative CHB patients with loss of hepatitis B surface antigen (HBsAg) or sustained undetectable HBV DNA levels who had discontinued NUCs therapy were included in the study.MethodsA total of 66 patients (2 patients with HBsAg loss and 64 patients with sustained undetectable HBV DNA levels) were examined. HBV DNA levels and alanine aminotransferase (ALT) levels were monitored regularly after discontinuation of NUCs therapy. Relapse was defined as HBV DNA levels >2,000 IU/mL while off therapy in at least two determinations more than 4 weeks apart.ResultsThe time to achieve undetectable HBV DNA levels was 14 weeks (interquartile range (IQR): 12–24 weeks). The time until consolidation therapy was 144 weeks (IQR: 96–168 weeks). No relapses occurred in either of the HBsAg loss patients. Among the 64 patients with undetectable HBV DNA levels, 19 (29.7%) patients demonstrated evidence of relapse. All the relapses occurred within 96 weeks after discontinuation. The median duration of relapse was 36 weeks (IQR: 12–48 weeks). Elevation of HBV DNA and ALT levels over baseline was only observed in 10% of the relapse patients. There were no significant differences among the baseline characteristics (sex, HBV genotype, age, or ALT level) or the time until consolidation therapy between relapse and sustained-response patients.ConclusionsNUC discontinuation is feasible after achieving undetectable HBV DNA levels in HBeAg-negative CHB patients. Prolonging the time until consolidation therapy may be a good strategy to decrease the rate of relapse. More than 96 weeks of sustained response is a predictive marker of long-term sustained response.

Disturbance plays a key role in driving ecological responses by creating opportunities for new ecological communities to assemble and by directly influencing the outcomes of assembly. Legacy effects (such as seed banks) and environmental filters can both influence community assembly, but their effects are impossible to separate with observational data. Here, we used seeding experiments in sites covering a broad range of postdisturbance conditions to tease apart the effects of seed availability, environmental factors, and disturbance characteristics on early community assembly after fire. We added seed of four common boreal trees to experimental plots in 55 replicate sites in recently burned areas of black spruce forest in northwestern North America. Seed addition treatments increased the probability of occurrence for all species, indicating a widespread potential for seed limitation to affect patterns of recruitment after fire. Small-seeded. species (aspen and birch) were most sensitive to environmental factors such as soil moisture and organic layer depth, suggesting a role for niche-based environmental filtering in community assembly. Fire characteristics related to severity and frequency were also important drivers of seedling regeneration, indicating the potential for disturbance to mediate environmental filters and legacy effects on seed availability. Because effects of seed availability are typically impossible to disentangle from environmental constraints on recruitment in observational studies, legacy effects contingent on vegetation history may be misinterpreted as being driven by strong environmental filters. Results from the seeding experiments suggest that vegetation legacies affecting seed availability play a pivotal role in shaping patterns of community assembly after fire in these low-diversity boreal forests.