Exosomes are a family of extracellular vesicles that are secreted from almost all types of cells and are associated with cell-to-cell communication. The present study was performed to investigate the effects of human induced pluripotent stem cell-derived exosomes (hiPSC-exo) on cell viability, capillary-like structure formation and senescence in endothelial cells exposed to high glucose. Exosomes were isolated from the conditional medium of hiPSCs and confirmed by transmission electron microscopy, nanoparticle tracking analysis and western blot analysis using Alix and cluster of differentiation-63 as markers. hiPSC-exo were labeled with PKH26 for tracking, and it was determined that spherical exosomes, with a typical cup-shape, were absorbed by human umbilical vascular endothelial cells (HUVECs). Cultured HUVECs were treated with high glucose (33 mM) with or without hiPSC-exo (20 µg/ml) for 48 h, and cell viability, capillary tube formation and senescence were assessed. When exposed to high glucose, viability and tube formation in HUVECs was significantly reduced (P<0.0001), whereas the proportion of senescent cells was higher compared with that in control HUVECs (P<0.0001). Furthermore, hiPSC-exo restored cell viability and capillary-like structure formation, and reduced senescence in HUVECs exposed to high glucose (P<0.0001). However, hiPSC-exo had minimal effects on normal HUVECs. These findings suggest that stem cell-derived exosomes are able to promote cell proliferation, enhance capillary-like structure formation and reduce senescence in endothelial cells exposed to high glucose.

No abstract

Pluripotent stem cells (PSCs) can undergo unlimited self-renewal and can differentiate into all the cell types present in our body, including cardiomyocytes. Therefore, PSCs can be an excellent source of cardiomyocytes for future regenerative medicine and medical research studies. However, cardiomyocytes obtained from PSC differentiation culture are regarded as immature structurally, electrophysiologically, metabolically, and functionally. Mitochondria are organelles responsible for various cellular functions such as energy metabolism, different catabolic and anabolic processes, calcium fluxes, and various signaling pathways. Cells can respond to cellular needs to increase the mitochondrial mass by mitochondrial biogenesis. On the other hand, cells can also degrade mitochondria through mitophagy. Mitochondria are also dynamic organelles that undergo continuous fusion and fission events. In this review, we aim to summarize previous findings on the changes of mitochondrial biogenesis, mitophagy, and mitochondrial dynamics during the maturation of cardiomyocytes. In addition, we intend to summarize whether changes in these processes would affect the maturation of cardiomyocytes. Lastly, we aim to discuss unanswered questions in the field and to provide insights for the possible strategies of enhancing the maturation of PSC-derived cardiomyocytes.

Hypoxia-inducible factor-1a (HIF-1a) is a main responder to intracellular hypoxia and is overexpressed in many human cancers, including renal cell carcinoma (RCC). To better understanding of the role of HIF-1a in the tumorigenicity of RCC, we used shorthairpin RNA (shRNA) interference to inhibit HIF-1a expression in the human renal cancer cell line, Caki-1 and OS-RC-2. Silencing of HIF-1a significantly reduced the expression of HIF-1a in both of renal cancer cell lines. In vitro downregulation of HIF-1a inhibited Caki-1 and OS-RC-2 cell growth, migration and invasion. The results further showed that HIF-1a silencing resulted in caspase-dependent apoptosis of Caki-1 and OS-RC-2 through regulation of PI3K/Akt pathway and Bcl-2-related proteins expression. In vivo animal studies showed that tumor growth was significantly inhibited in HIF-1a shRNA-transfected RCC. Intratumor gene therapy with polyethylenimine-loaded HIF-1a shRNA also resulted in tumor growth suppression. Thus, this study demonstrates that downregulation of HIF-1a could suppress tumorigenicity of RCC through induction of apoptosis, and HIF-1a shRNA may be a promising strategy for the treatment of RCC.

No abstract

No abstract

Acute respiratory distress syndrome (ARDS) is a disease that seriously threatens human life and health. The aim of the study was to investigate the effects of ulinastatin combined with mechanical ventilation on oxygen metabolism, inflammation and stress response, as well as the antioxidant capacity of ARDS. Eighty patients with ARDS treated in Yiwu Central Hospital from January, 2015 to December, 2016 were enrolled in the present study and divided into the observation (n=40) and control (n=40) groups, using a random number table. The control group was treated with mechanical ventilation, while the observation group, based on treatment of the control group, was treated with ulinastatin for 14 consecutive days as one course of treatment. The changes in the relevant indexes of oxygen metabolism, lung function, time of ventilator treatment, total hospital stay, and St. George's Respiratory Questionnaire (SGRQ) score of the two groups after intervention were compared, and the changes in inflammatory cytokine levels, dopamine receptor-related hormone levels, superoxide dismutase (SOD), malondialdehyde (MDA) and total antioxidant capacity of the two groups before intervention and at 1 and 4 weeks after intervention were compared. After intervention, the arterial blood lactate in the observation group was significantly lower than that in the control group (P<0.05), the oxygen uptake rate was significantly higher than that in the control group (P<0.05) and the arterial oxygen content was significantly higher than that in the control group (P<0.05). In the lung function indexes, the FEV1 and FEV1/FVC levels in the observation group were smaller than those in the control group (P<0.05), the duration of ventilator treatment was significantly shorter than that in the control group (P<0.05), and the hospital stay was significantly less than that in the control group (P<0.05). Prior to intervention, SGRQ scores in the two groups were not statistically significant (P>0.05). At 1 and 4 weeks after intervention, the SGRQ scores of the observation group were significantly increased to those of the control group (P<0.05). The tumor levels of necrosis factor-α (TNF-α), interleukin-6 (IL-6) and CRP were significantly lower than those of the control group (P<0.05). The levels of adrenaline and norepinephrine were significantly lower than those of the control group (P<0.05). The levels of MDA, SOD and the total antioxidant capacity were significantly increased to those of control group (P<0.05). The application of ulinastatin combined with mechanical ventilation in ARDS patients is of great significance in improving the oxygen delivery-consumption balance of body, increasing the lung function, reducing the inflammatory and stress response, and improving the antioxidant capacity.

Aims Remdesivir is a prodrug of an adenosine triphosphate analogue and is currently the only drug formally approved for the treatment of hospitalised COVID-19 patients. Nucleoside/nucleotide analogues have been shown to induce mitochondrial damage and cardiotoxicity, and this may be exacerbated by hypoxia, which frequently occurs in severe COVID-19 patients. Although there have been few reports of adverse cardiovascular events associated with remdesivir, clinical data are limited. Here, we investigated whether remdesivir induced cardiotoxicity using an in vitro human cardiac model. Methods and Results Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were exposed to remdesivir under normoxic and hypoxic conditions to simulate mild and severe COVID-19 respectively. Remdesivir induced mitochondrial fragmentation, reduced redox potential and suppressed mitochondrial respiration at levels below the estimated plasma concentration under both normoxic and hypoxic conditions. Non-mitochondrial damage such as electrophysiological alterations and sarcomere disarray were also observed. Importantly, some of these changes persisted after the cessation of treatment, culminating in increased cell death. Mechanistically, we found that inhibition of DRP1, a regulator of mitochondrial fission, ameliorated the cardiotoxic effects of remdesivir, showing that remdesivir-induced cardiotoxicity was preventable and excessive mitochondrial fission might contribute to this phenotype. Conclusions Using an in vitro model, we demonstrated that remdesivir can induce cardiotoxicity in hiPSC-CMs at clinically relevant concentrations. These results reveal previously unknown potential side-effects of remdesivir and highlight the importance of further investigations with in vivo animal models and active clinical monitoring to prevent lasting cardiac damage to patients. Translational perspective Adult cardiomyocytes have limited ability to regenerate, thus treatment-induced cardiotoxicity can potentially cause irreparable harm. Remdesivir is currently the only FDA approved treatment for COVID-19 but clinical safety data are limited. Using human pluripotent stem cell-derived cardiomyocytes, we revealed that remdesivir induced persistent mitochondrial and structural abnormalities at clinically relevant concentrations. We advise confirmatory experiments in in vivo animal models, investigations of cardioprotective strategies, and closer patient monitoring such that treatment-induced cardiotoxicity does not contribute to the long term sequelae of COVID-19 patients.