Effect of CXCR4 pretreated with ultrasound-exposed microbubbles on accelerating homing of bone marrow mesenchymal stem cells to ischemic myocardium in AMI rats

Objective: To investigate the role and potential mechanism of CXCR4 in promoting targeted homing of bone marrow mesenchymal stem cells(BMSCs) with ultrasound-exposed microbubbles(UM) pretreatment. Methods: Third generation BMSCs were divided into four groups control group, ultrasound(US) group, UM group and ultrasound-exposed microbubbles plus catalase group. RT-PCR and western blot were performed to determine the levels of CXCR4 m RNA transcription and protein expression, respectively. Third generation BMSCs were labeled with Fluo-α/AM and divided into three groups: control group, US group and UM group, and flurorescence intensities in the cells were observed immediately, 5 min and 15 min after intervention underflurorescence microscope. The calcium iron levels in the cells were analyzed. BMSCs were divided into i ve group: group A without calcium in the medium, group B, group C, group D and group E containing calcium chloride with concentration of l mol, 2 mol, 4mol, anti-calciurn-sensing receptor antibody, respectively. RT-PCR and western blot were performed to determine the levels of CXCR4 m RNA transcription and proteins expression of the third generation BMSCs of each group, respectively. Results: The levels of CXCR4 m RNA transcription and protein expression between US group and control group had no statistically signii cant dif erence(P>0.05) shown by RT-PCR and western blot; the transcription level in the UM group was signii cantly higher than that in US group and control group(P<0.05); and in the ultrasound-exposed microbubbles plus catalase group, the transcription level was much lower than that in UM group. Fluorescence intensify in the cells of US group had no signii cant dif erence compared with that in the cells of the control group(P>0.05), which in the cells of UM group was signii cantly higher than that in the cells of both US group and control group(P<0.05). Compared to group A, expressions of CXCR4 of group B to D were signii cantly increased in concentration-dependent manner showed by RT-PCR and western blot(P< 0.05). Compared to group C, expressions of CXCR4 of group E were signii cantly decreased(P< 0.05). Conclusions: UM can promote the inl ux of calcium in BMSCs and increase m RNA transcription and protein expression of CXCR4. The latter may partly be caused by influx of calcium.

Long-term stability and protection efficacy of the RBD-targeting COVID-19 mRNA vaccine in nonhuman primates

Messenger RNA(mRNA)vaccine technology has shown its power in preventing the ongoing COVID-19 pandemic.Two mRNA vaccines targeting the full-length S protein of SARS-CoV-2 have been authorized for emergency use.Recently,we have developed a lipid nanoparticle-encapsulated mRNA(mRNA-LNP)encoding the receptor-binding domain(RBD)of SARS-CoV-2(termed ARCoV),which confers complete protection in mouse model.Herein,we further characterized the protection efficacy of ARCoV in nonhuman primates and the Iong-term stability under normal refrigerator temperature.Intramuscular immunization of two doses of ARCoV elicited robust neutralizing antibodies as well as cellular response against SARS-CoV-2 in cynomolgus macaques.More importantly,ARCoV vaccination in macaques significantly protected animals from acute lung lesions caused by SARS-CoV-2,and viral replication in lungs and secretion in nasal swabs were completely cleared in all animals immunized with low or high doses of ARCoV.No evidenee of antibody-dependent enhancement of infection was observed throughout the study.Finally,extensive stability assays showed that ARCoV can be stored at 2-8℃ for at least 6 months without decrease of immunogenicity.All these promising results strongly support the ongoing clinical trial.

A Critical Time-Window for the Selective Induction of Hippocampal Memory Consolidation by a Brief Episode of Slow-Wave Sleep

Although extensively studied, the exact role of sleep in learning and memory is still not very clear. Sleep deprivation has been most frequently used to explore the effects of sleep on learning and memory, but the results from such studies are inevitably complicated by concurrent stress and distress. Furthermore, it is not clear whether there is a strict time-window between sleep and memory consolidation. In the present study we were able to induce time-locked slow-wave sleep(SWS) in mice by optogenetically stimulating GABAergic neurons in the parafacial zone(PZ), providing a direct approach to analyze the influences of SWS on learning and memory with precise time-windows. We found that SWS induced by light for 30 min immediately or 15 min after the training phase of the object-in-place task significantly prolonged the memory from 30 min to 6 h. However, induction of SWS 30 min after the training phase did not improve memory, suggesting a critical time-window between the induction of a brief episode of SWS and learning for memory consolidation.Application of a gentle touch to the mice during light stimulation to prevent SWS induction also failed to improve memory, indicating the specific role of SWS,but not the activation of PZ GABAergic neurons itself, in memory consolidation. Similar influences of light-induced SWS on memory consolidation also occurred for Y-maze spatial memory and contextual fear memory, but not for cued fear memory. SWS induction immediately before the test phase had no effect on memory performance, indicating that SWS does not affect memory retrieval. Thus, by induction of a brief-episode SWS we have revealed a critical time window for the consolidation of hippocampusdependent memory.

The infectivity and pathogenicity of hepatitis A virus live-attenuated vaccine strain H2 in type I interferon receptor-deficient mice

Hepatitis A virus(HAV)live-attenuated vaccine H2 strain has been approved for clinical use for decades with ideal safety profiles in nonhuman primate models and humans.Recently,type Ⅰ interferon(IFN)receptor-deficient mice were shown to be susceptible to HAV infection.Herein,we sought to determine the infection and replication dynamics of the H2 in Ifnar^(-/-)mice that lack type Ⅰ IFN receptor.Following intravenous injection,the H2 failed to cause obvious clinical symptoms in Ifnar^(-/-)mice,and no significant upregulation in serum alanine aminotransferase(ALT)levels was observed.Notably,the histopathological examination showed that there were significant focal infiltrations of lymphocytes and neutrophils in the portal area,but no focal necrosis was observed in liver tissues.Viral RNAs sustained in the liver,and the infectious virus could be recovered from the liver tissue until 42 days post-infection.More importantly,H2 infection induced obvious viremia and persistent viral shedding in feces.In addition,robust HAV-specific humoral immune responses were induced in Ifnar^(-/-)mice.Overall,our study revealed the safety profile of H2 in Ifnar^(-/-)mice,which not only helps understand the attenuation mechanism of H2,but also expands the application of the Ifnar^(-/-)mouse model for HAV studies.