The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19) and the ensuing worldwide pandemic. The spread of the virus has had global effects such as activity restriction, economic stagnation, and collapse of healthcare infrastructure. Severe SARS-CoV-2 infection induces a cytokine storm, leading to acute respiratory distress syndrome (ARDS) and multiple organ failure, which are very serious health conditions and must be mitigated or resolved as soon as possible. Mesenchymal stem cells (MSCs) and their exosomes can affect immune cells by inducing anti-inflammatory macrophages, regulatory T and B cells, and regulatory dendritic cells, and can inactivate T cells. Hence, they are potential candidate agents for treatment of severe cases of COVID-19. In this review, we report the background of severe cases of COVID-19, basic aspects and mechanisms of action of MSCs and their exosomes, and discuss basic and clinical studies based on MSCs and exosomes for influenza-induced ARDS. Finally, we report the potential of MSC and exosome therapy in severe cases of COVID-19 in recently initiated or planned clinical trials of MSCs (33 trials) and exosomes (1 trial) registered in 13 countries on ClinicalTrials.gov.

Background Delayed bleeding is an important complication after gastric endoscopic submucosal dissection (ESD). The search, coagulation, and clipping (SCC) method can be used to prevent delayed bleeding after ESD. However, its safety and efficacy are unclear. We compared the SCC method with post-ESD coagulation (PEC) to clarify the safety and efficacy of the SCC method for preventing delayed bleeding after gastric ESD. Methods This retrospective study included 438 patients (478 lesions) who underwent gastric ESD. Multivariate logistic regression analysis was performed to identify the significant independent factors associated with delayed bleeding and we performed propensity-score matching (PSM) to reduce the effect of procedure-selection bias of SCC method. Results Of the 438 patients, 216 underwent PEC and 222 underwent SCC. Delayed bleeding was significantly less common in the SCC than in the PEC (2.6% vs. 7.2%; P = 0.013). Among patients treated with antithrombotic therapy, the delayed bleeding rate was lower in the SCC group than in the PEC group; however, the difference was not significant ( P = 0.15). The SCC method was found to be a significant independent factor for the prevention of delayed bleeding. PSM was performed in 156 patients in the PEC group and SCC group. There was a significant difference in the incidence of bleeding in the PEC and SCC groups ( P = 0.013). No patient had perforation/bleeding associated with the SCC method. Conclusions Our findings suggest that the SCC method is a simple, safe, and effective approach for preventing delayed bleeding after gastric ESD.

Aim: Non-alcoholic steatohepatitis (NASH) with fibrosis eventually leads to cirrhosis and hepatocellular carcinoma. Thus, the development of therapies other than dietary restriction and exercise, particularly those that suppress steatosis and fibrosis of the liver and have a long-term beneficial effect, is necessary. We aimed to evaluate the therapeutic effects of the HMGB1 peptide synthesized from box A using the melanocortin-4 receptor-deficient (Mc4r-KO) NASH model mouse. Methods:We performed short-and long-term administration of this peptide and evaluated the effects on steatosis, fibrosis, and carcinogenesis using Mc4r-KO mice.We also analyzed the direct effect of this peptide on macrophages and hepatic stellate cells in vitro and performed lipidomics and metabolomics techniques to evaluate the effect.Results: Although this peptide did not show direct effects on macrophages and hepatic stellate cells in vitro, in the short-term administration model, we could confirm the reduction of liver damage, steatosis, and fibrosis progression. The results of lipidomics and metabolomics suggested that the peptide might ameliorate NASH by promoting lipolysis via the activation of fatty acid β-oxidation and improving insulin resistance. In the long-term administration model, this peptide prevented progression to cirrhosis but retained the steatosis state, that is, the peptide prevents the progression to "burnt-out NASH." This peptide inhibited carcinogenesis by about one-third. Conclusion:This HMGB1 peptide can reduce liver damage, improve fibrosis and steatosis, and inhibit carcinogenesis, suggesting that the peptide would be a new treatment candidate for NASH and can contribute to the long-term prognosis for patients with NASH.

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