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Rationale: Peripheral nerves are unique in their remarkable elasticity. Schwann cells (SCs), important components of the peripheral nervous system (PNS), are constantly subjected to physiological and mechanical stresses from dynamic stretching and compression forces during movement. So far, it is not clear if SCs sense and respond to mechanical signals. It is also unknown whether mechanical stimuli can interfere with the intercellular communications between neurons and SCs, and what role extracellular vesicles (EVs) play in this process. The present study aimed to examine the effect of mechanical stimuli on the EV-mediated intercellular communication between neurons and SCs, explore their effect on axonal regeneration, and investigate the underlying mechanism. Methods: Purified SCs were stimulated using a magnetic force-based mechanical stimulation (MS) system and EVs were purified from mechanically stimulated SCs (MS-SCs-EVs) and non-stimulated SCs (SCs-EVs). The effect of MS-SCs-EVs on axonal elongation was examined in vitro and in vivo. High throughput miRNA sequencing was performed to compare the differential miRNA profiles between MS-SCs-EVs and SCs-EVs. The functional role of differentially expressed miRNAs on neurite extension in MS-SCs-EVs was examined. Also, the putative target genes of differentially expressed miRNAs in MS-SCs-EVs were predicted by bioinformatics tools, and the regulatory effect of those miRNAs on putative target genes was validated both in vitro and in vivo. Results: The MS-SCs-EVs showed an average size of 137.52±1.77 nm, and could be internalized by dorsal root ganglion (DRG) neurons. Compared to SCs-EVs, MS-SCs-EVs showed a stronger ability to enhance neurite outgrowth in vitro and nerve regeneration in vivo. High throughput miRNA sequencing identified a number of differentially expressed miRNAs in MS-SCs-EVs. Further analysis of those EV-miRNAs demonstrated that miR-23b-3p played a predominant role in MS-SCs-EVs since its deprivation abolished their enhanced axonal elongation. Furthermore, we identified neuropilin 1 (Nrp1) in neurons as the target gene of miR-23b-3p in MS-SCs-EVs. This observation was supported by the evidence that miR-23b-3p could decrease Nrp1-3'-UTR-WT luciferase activity in vitro and down-regulate Nrp1 expression in neurons. Conclusion: Our findings suggested that mechanical stimuli are capable of modulating the intercellular communication between neurons and SCs by altering miRNA composition in MS-SCs-EVs. Transfer of miR-23b-3p by MS-SCs-EVs from mechanically stimulated SCs to neurons decreased neuronal Nrp1 expression, which was responsible, at least in part, for the beneficial effect of MS-SCs-EVs on axonal regeneration. Our results highlighted the potential therapeutic value of MS-SCs-EVs and miR-23b-3p-enriched EVs in peripheral nerve injury repair.

Current pharmacological intervention for the treatment of osteolytic bone diseases such as osteoporosis focuses on the prevention of excessive osteoclastic bone resorption but does not enhance osteoblast-mediated bone formation. In our study, we have shown that 4-iodo-6-phenylpyrimidine (4-IPP), an irreversible inhibitor of macrophage migration inhibitory factor (MIF), can inhibit receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis and potentiate osteoblast-mediated mineralization and bone nodule formation

Rationale: Local hypoxia is a challenge for fabrication of cellular grafts and treatment of peripheral nerve injury. In our previous studies, we demonstrated that perfluorotributylamine (PFTBA) could provide short term oxygen supply to Schwann cells (SCs) and counteract the detrimental effects of hypoxia on SCs during the early stages of nerve injury. However, the quick release of oxygen in PFTBA compromised its ability to counteract hypoxia over an extended time, limiting its performance in peripheral nerve injury. Methods: In this study, PFTBA-based oxygen carrier systems were prepared through coaxial electrospinning to prolong the time course of oxygen release. Core-shell structures were fabricated, optimized, and the oxygen kinetics of PFTBA-enriched core-shell fibers evaluated. The effect of core-shells on the survival and function of SCs was examined in both 2D and 3D systems as well as in vivo. The system was used to bridge large sciatic nerve defects in rats. Results: PFTBA core-shell fibers provided high levels of oxygen to SCs in vitro, enhancing their survival, and increasing NGF, BDNF, and VEGF expression in 2D and 3D culture systems under hypoxic condition. In vivo analysis showed that the majority of GFP-expressing SCs in the PFTBA conduit remained viable 14 days post-implantation. We found that axons in PFTBA oxygen carrier scaffold improved axonal regeneration, remyelination, and recovery. Conclusion: A synthetic oxygen carrier in core-shell fibers was fabricated by the coaxial electrospinning technique and was capable of enhancing SC survival and nerve regeneration by prolonged oxygen supply. These findings provide a new strategy for fabricating cellular scaffolds to achieve regeneration in peripheral nerve injury treatment and other aerobic tissue injuries.

Osteoporosis (OP) is a serious metabolic disease that, due to the increased number or function of osteoclasts, results in increased bone brittleness and, therefore, fragile fracture. Some recent studies report the importance of the transforming growth factor β (TGFβ) pathway in bone homeostasis. RepSox is a small molecule inhibitor of TGFβRI that has a wide range of potential application in clinical medicine, except OP. The aim of our study is to evaluate the effects of RepSox on the differentiation and bone resorption of osteoclasts in vitro and in vivo in an ovariectomy (OVX)-induced OP model. An initial analysis showed TGFβRI messenger RNA expression in both bone samples and bone cells. In the in vitro study, RepSox inhibited the receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclast differentiation and bone resorption activity. Real-time polymerase chain reaction (PCR) analysis showed that RepSox suppressed osteoclastic marker gene expression in both dose-dependent and time-dependent manners. In addition, RepSox did not affect osteoblast differentiation, migration or osteoblastic-specific gene expression in vitro. Furthermore, western blot analysis indicated the underlying mechanisms of the RepSox suppression of osteoclastogenesis via the Smad3 and c-Jun N-terminal kinase/activator protein-1 (JNK/AP-1) signaling pathways. Finally, our animal experiments revealed that RepSox prevented OVX-induced bone loss in vivo. Together, our data suggest that RepSox regulates osteoclast differentiation, bone resorption, and OVX-induced OP via the suppression of the Smad3 and JNK/AP-1 pathways.

Rationale In 1891, Dr. Hermann Kummell, a German surgeon, described a clinical entity characterized by the development of progressive painful kyphosis following an asymptomatic period of months or years after a minor spinal trauma, leading to a gradual collapse of the vertebra and dynamic instability, ultimately progressing to kyphosis with prolonged back pain and/or paraparesis. To date, the main pathologic eliciting event remains unclear, and no standard treatment or single effective treatment are available for Kummell disease. Patient concerns A 74-year-old woman presented with severe back pain and numbness of both legs for approximately 2 months. Diagnoses According to the clinical symptoms and imaging examinations, the patient was diagnosed with stage III Kummell disease. Interventions The patient underwent titanium mesh bone grafting combined with pedicle screw internal fixation. Outcomes Postoperative kyphosis was corrected, and the vertebra was reconstructed. Lessons Kummell disease is not a rare complication of osteoporotic vertebral compression fractures, and treatment of each patient must be individualized. The application of titanium mesh bone grafting combined with pedicle screw internal fixation is an effective treatment option for stage III Kummell disease.