Background: The development of new treatment strategies to improve peripheral nerve repair after injury, especially those that accelerate axonal nerve regeneration, is very important. The aim of this study is to elucidate the molecular mechanisms of how bone marrow stromal cell (BMSC)-derived exosomes (EXOs) participate in peripheral nerve regeneration and whether the regenerative effect of EXOs is correlated with dose.Method: BMSCs were transfected with or without an siRNA targeting Ago2 (SiAgo2). EXOs extracted from the BMSCs were administered to dorsal root ganglion (DRG) neurons in vitro. After 48 h of culture, the neurite length was measured. Moreover, EXOs at four different doses were injected into the gastrocnemius muscles of rats with sciatic nerve crush injury. The sciatic nerve functional index (SFI) and latency of thermal pain (LTP) of the hind leg sciatic nerve were measured before the operation and at 7, 14, 21, and 28 days after the operation. Then, the number and diameter of the regenerated fibers in the injured distal sciatic nerve were quantified. Seven genes associated with nerve regeneration were investigated by qRT-PCR in DRG neurons extracted from rats 7 days after the sciatic nerve crush.Results: We showed that after 48 h of culture, the mean number of neurites and the length of cultured DRG neurons in the SiAgo2-BMSC-EXO and SiAgo2-BMSC groups were smaller than that in the untreated and siRNA control groups. The average number and diameter of regenerated axons, LTP, and SFI in the group with 0.9 × 10¹⁰particles/ml EXOs were better than those in other groups, while the group that received a minimum EXO dose (0.4 × 10¹⁰particles/ml) was not significantly different from the PBS group. The expression of PMP22, VEGFA, NGFr, and S100b in DRGs from the EXO-treated group was significantly higher than that in the PBS control group. No significant difference was observed in the expression of HGF and Akt1 among the groups.Conclusions: These results showed that BMSC-derived EXOs can promote the regeneration of peripheral nerves and that the mechanism may involve miRNA-mediated regulation of regeneration-related genes, such as VEGFA. Finally, a dose-effect relationship between EXO treatment and nerve regeneration was shown.

Our general purpose was to provide a theoretical and practical foundation for the use of exosomes (EXOs) that have high levels of CD47 as stable and efficient drug carriers. Thus, we prepared EXOs from adipose tissue-derived mesenchymal stromal cells (ADMSCs) that had high levels of CD47 (EXOs^CD47) and control EXOs (without CD47), and then compared their immune escapein vivoand their resistance to phagocytosisin vitro. Nanoflow cytometry was used to determine the CD47 level in these EXOs, and the amount of EXOs^CD47that remained in rat plasma at 3 h after intraperitoneal injection. Phagocytosis of the EXOs was also determined usingin vitrorat macrophage bone marrow (RMA-BM) experiments. Ourin vitroresults showed that macrophages ingested significantly more control EXOs than EXOs^CD47(p< 0.01), with confirmation by ultra-high-definition laser confocal microscopy. Consistently, ourin vivoresults showed that rats had 1.377-fold better retention of EXOs^CD47than control EXOs (p< 0.01). These results confirmed that these engineered EXOs^CD47had improved immune escape. Our results therefore verified that EXOs^CD47had increased immune evasion relative to control EXOs, and have potential for use as drug carriers.

We investigated the occurrence of mesenchymal stem cell (MSC)-derived exosome uptake and retrograde transport at peripheral nerve endings using bone marrow MSCs (bMSCs) transduced with recombinant CD63-green fluorescent protein (GFP) lentiviral plasmid. GFP was used to track the release of bMSC-derived exosomes and the uptake and transport at peripheral nerve terminals, the dorsal root ganglion (DRG), and the spinal cord. In vitro cell culture and injection of a CD63-GFP exosome suspension into the right gastrocnemius muscle of an in vivo rat model were also performed. Fluorescence microscopy of co-cultured CD63-GFP exosomes and SH-SY5Y or BV2 cell lines and primary cultured DRG cells in a separate experiment demonstrated exosome uptake into DRG neurons and glia. Moreover, we observed both retrograde axoplasmic transport and hematogenous transport of exosomes injected into rat models at the DRG and the ipsilateral side of the anterior horn of the spinal cord using fluorescence microscopy, immunohistochemistry, and Western blot analyses. In conclusion, we showed that exosome uptake at peripheral nerve endings and retrograde transport of exosomes to DRG neurons and spinal cord motor neurons in the anterior horn can occur. In addition, our findings propose a novel drug delivery approach for treating neuronal diseases.

Cervical cancer is a major cause of death in women worldwide. Interferon-induced transmembrane protein 1 (IFITM1) is involved in antivirus defense, cell adhesion, and carcinogenesis in different tissues. However, the role of IFITM1 gene in cervical squamous cell cancer is unclear. To explore the role of IFITM1 in carcinogenesis of cervical cancer, we investigated the expression of IFITM1 gene in cervical squamous cell carcinoma. IFITM1 mRNA level was measured by real-time quantitative RT-PCR in cervical cancer tissues and their adjacent normal tissues. IFITM1 protein level was measured by immunohistochemistry. Methylation in the IFITM1 gene promoter was detected by methylation-specific PCR. We then transfected HeLa cells with IFITM1 expression vector or control vector. IFITM1 expression was examined; cell migration and invasion were analyzed by wound healing assay and matrigel-coated transwell migration assays, respectively. HeLa cell proliferation was measured by cell counting kit-8 assay and cell cycle analysis. Cell apoptosis was analyzed by Annexin V/propidium iodide double staining assay. The difference in IFITM1 protein expression between samples from chronic cervicitis and cervical carcinoma was statistically significant (P < 0.01). Ki-67 and PCNA protein expression levels were significantly higher in cervical cancer tissues than in their corresponding cervicitis tissues (P < 0.05 and P < 0.001, respectively). IFITM1 mRNA level was significantly lower in cervical cancer tissues than in normal cervical tissues (P < 0.05). Methylation of the IFITM1 gene promoter was significantly higher in cervical cancer than in normal cervical tissues (P < 0.05). Transfection of the IFITM1 pcDNA3.1 construct decreased cell migration and invasion of HeLa cells, inhibited cell proliferation, and increased cell apoptosis. IFITM1 gene expression may reduce the proliferation, migration, and invasion of cervical squamous cancer cells.

Peripheral nerve injury is one of the more common forms of peripheral nerve disorders, and the most severe type of peripheral nerve injury is a defect with a gap. Biosynthetic cellulose membrane (BCM) is a commonly used material for repair and ligation of nerve defects with gaps. Meanwhile, exosomes from mesenchymal stem cells can promote cell growth and proliferation. We envision combining exosomes with BCMs to leverage the advantages of both to promote repair of peripheral nerve injury. Prepared exosomes were added to BCMs to form exosome-loaded BCMs (EXO-BCM) that were used for nerve repair in a rat model of sciatic nerve defects with gaps. We evaluated the repair activity using a pawprint experiment, measurement and statistical analyses of sciatica function index and thermal latency of paw withdrawal, and quantitation of the number and diameter of regenerated nerve fibers. Results indicated that EXO-BCM produced comprehensive and durable repair of peripheral nerve defects that were similar to those for autologous nerve transplantation, the gold standard for nerve defect repair. EXO-BCM is not predicted to cause donor site morbidity to the patient, in contrast to autologous nerve transplantation. Together these results indicate that an approach using EXO-BCM represents a promising alternative to autologous nerve transplantation, and could have broad applications for repair of nerve defects.