Tendon–bone insertion (TBI) injuries, such as anterior cruciate ligament injury and rotator cuff injury, are the most common soft tissue injuries. In most situations, surgical tendon/ligament reconstruction is necessary for treating such injuries. However, a significant number of cases failed because healing of the enthesis occurs through scar tissue formation rather than the regeneration of transitional tissue. In recent years, the therapeutic potential of mesenchymal stem cells (MSCs) has been well documented in animal and clinical studies, such as chronic paraplegia, non-ischemic heart failure, and osteoarthritis of the knee. MSCs are multipotent stem cells, which have self-renewability and the ability to differentiate into a wide variety of cells such as chondrocytes, osteoblasts, and adipocytes. Numerous studies have suggested that MSCs could promote angiogenesis and cell proliferation, reduce inflammation, and produce a large number of bioactive molecules involved in the repair. These effects are likely mediated by the paracrine mechanisms of MSCs, particularly through the release of exosomes. Exosomes, nano-sized extracellular vesicles (EVs) with a lipid bilayer and a membrane structure, are naturally released by various cell types. They play an essential role in intercellular communication by transferring bioactive lipids, proteins, and nucleic acids, such as mRNAs and miRNAs, between cells to influence the physiological and pathological processes of recipient cells. Exosomes have been shown to facilitate tissue repair and regeneration. Herein, we discuss the prospective applications of MSC-derived exosomes in TBI injuries. We also review the roles of MSC–EVs and the underlying mechanisms of their effects on promoting tendon–bone healing. At last, we discuss the present challenges and future research directions. Graphical Abstract

Lithium sulfur (Li-S) batteries are considered one of the most promising energy storage devices due to their high specific capacity, pollution-free reactant, and low cost. However, the “shuttle effect” of lithium polysulfide (Li2S x ) leads to a fast capacity decay and poor cycle life. Here, the magnetorheological effect (MRE) is first applied in Li-S batteries and a magnetic control electrolyte is designed by introducing carbonyl iron powders (CIPs) to improve the performance of Li-S batteries. According to adsorption bonding theory, the binding energy of Fe site with Li2S4 is up to 2.68 eV via discrete Fourier transform (DFT) calculation. After coupling an external magnetic field, the uniform distribution of CIPs avoids the accumulation on the cathode surface. The induced magnetic field of spherical particles captures dissolved S x 2− effectively by Lorenz force, which is confirmed by adsorption experiments. These magnetized particles form a magnetic shield layer in the electrolyte and alleviate the “shuttle effect.” At 0.2 C, the initial specific capacity reaches 1296 mAh g−1. Magnetic control electrolyte provides not only a novel insight but also creates a new possibility for mitigating the “shuttle effect” thereby promoting performance of Li-S batteries.

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Lithium-sulfur (Li-S) battery is one of the most prospective energy storage devices due to its high specific capacity, low cost and pollution-free reactant. However, the degradation of anode lithium metal and the formation of lithium dendrites seriously shorten the cycle life and reduce its safety. It’s a bad obstacle for the application of Li-S batteries. In this work, comparing and analyzing reported applications of the magnetic field simple parallel or perpendicular to the direction of the electric field, one central symmetric and curved magnetic field which is firstly coupled to Li-S batteries has unique advantage. With this magnetic field, lithium ions are subjected to centripetal Lorentz force (FB), and the trajectory of Li+ is transformed from linear aggregation deposition to rotational uniform deposition, inhibiting the formation of lithium dendrites. With 70 mT, the capacity attenuation rate is 0.14%, which is almost a quarter of that with 0 mT. The results of scanning electron microscope (SEM) images show that there are fewer cracks and bulges on the surface of anode with the magnetic field. It can be ascribed to the magnetohydrodynamics (MHD) effect, and the mechanism is also confirmed by the multi-physics field simulation. In summary, this study proves that the central symmetric and curved magnetic field develops a new possibility for mitigating lithium dendrites and improving performance of Li-S batteries.