Epithelial mesenchymal transition (EMT),

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No effective drug treatments are available for coronavirus disease 2019 (COVID-19). Host-directed therapies targeting the underlying aberrant immune responses leading to pulmonary tissue damage, death, or long-term functional disability in survivors require clinical evaluation. We performed a parallel assigned controlled, non-randomized, phase 1 clinical trial to evaluate the safety of human umbilical cord-derived mesenchymal stem cells (UC-MSCs) infusions in the treatment of patients with moderate and severe COVID-19 pulmonary disease. The study enrolled 18 hospitalized patients with COVID-19 (n = 9 for each group). The treatment group received three cycles of intravenous infusion of UC-MSCs (3 × 10 7 cells per infusion) on days 0, 3, and 6. Both groups received standard COVID-treatment regimens. Adverse events, duration of clinical symptoms, laboratory parameters, length of hospitalization, serial chest computed tomography (CT) images, the PaO 2 /FiO 2 ratio, dynamics of cytokines, and IgG and IgM anti-SARS-CoV-2 antibodies were analyzed. No serious UC-MSCs infusion-associated adverse events were observed. Two patients receiving UC-MSCs developed transient facial flushing and fever, and one patient developed transient hypoxia at 12 h post UC-MSCs transfusion. Mechanical ventilation was required in one patient in the treatment group compared with four in the control group. All patients recovered and were discharged. Our data show that intravenous UC-MSCs infusion in patients with moderate and severe COVID-19 is safe and well tolerated. Phase 2/3 randomized, controlled, double-blinded trials with long-term follow-up are needed to evaluate the therapeutic use of UC-MSCs to reduce deaths and improve long-term treatment outcomes in patients with serious COVID-19.

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Methylammonium lead iodide perovskite, CH 3 NH 3 PbI 3 (MAPbI 3 ), has made great progress in its efficiency as used in solid-state solar cells during recent years. Meanwhile, the degradation of its performance in moisture has attracted great attentions, but the specific mechanismis not yet fully established. The water effects on the detailed structure and properties of the perovskite CH 3 NH 3 PbI 3 have been carefully explored based on first-principles calculations. The results reveals that the water adsorption energy on the CH 3 NH 3 PbI 3 (001) surface is about 0.30 eV, while the water can easily penetrate into the surface in the form of molecular state owing to the huge interspace of CH 3 NH 3 PbI 3 , which can further corrode down the whole structure gradually. More importantly, the deformation of the structure greatly affects the electronic structure, which decreases the optical absorption. Such work paves an important way to understand the initial degradation progress of the perovskite structure under the humidity condition, which should help to optimize the structure to prevent the penetration of water in the system. The conversion of solar energy into electricity has attracted great attentions because of the increasing energy demands of future generations without negatively impacting the global environment. 1-2 On the other hand, dye-sensitized solar cells (DSCs) based on nanocrystalline metal oxides like TiO 2 3-4 are a promising photovoltaic device for a renewable energy source. In recent years, new organic-inorganic hybrid perovskite compounds (MAPbX 3 , X=halogen; MA=CH 3 NH 3 ) 5-11 have been used as light harvesters for solid-state DSCs. These MAPbX 3 compounds stand out for their low cost, wide light absorption, ferroelectric properties and high efficiency. 12-18 In fact, since the first reported perovskite solar cell with power conversion efficiency (PCE) of 3.81% by Kojima and co-workers in 2009, 19 the amazing growth rate of PCE about these perovskite materials has been made in the following years. In 2011, Park et al. fabricated MAPbI 3 perovskite solar cells with PCE of 6.54%. 20 Then Kim et al. achieved a PCE of up to 9.7% based on spiro-MeOTAD as hole transport materials in 2012. 21 In 2013, Noh et al. demonstrated highly efficient solar cells of a PCE of 12.3% as a result of tunable composition for MAPb(I 1-x Br x ) 3 . 22 In 2014, Grätzel and co-workers reported an efficiency of 17.01% by controlling the size of MAPbI 3 cuboids during their growth. 23 Up to now, the PCE of perovskite-based solar cells reaches to nearly 20%. 7 Although the methylammonium lead iodide MAPbI 3 perovskite shows an outstanding performance and tantalizing prospect in solar cells, there are deficiencies needed to overcome at the same time. One vital problems is that MAPbI 3 perovskite films are extremely sensitive to moisture in air. 7-8, 24-27 Many experiments have demonstrated that the effect of moisture on MAPbI 3 plays a crucial role in the performance of perovskite solar cells. 22, 28-30 In spite of various...