No abstract

No abstract

Transforming growth factor β1 (TGF-β1) has been suggested to be a candidate cytokine in the field of bone tissue engineering. Cytokines serve important roles in tissue engineering, particularly in the repair of bone damage; however, the underlying molecular mechanisms remain unclear. In the present study, the effects of TGF-β1 on the osteogenesis and motility of hFOB1.19 human osteoblasts were demonstrated via the phenotype and gene expression of cells. Additionally, the role of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin/S6 kinase 1 (PI3K/AKT/mTOR/S6K1) signalling pathway in the effects of TGF-β1 on osteoblasts was investigated. It was demonstrated using Cell Counting Kit-8 and flow cytometry assays that the proliferation of human osteoblasts was promoted by 1 ng/ml TGF-β1. In addition, alkaline phosphatase activity, Alizarin red staining, scratch-wound and Transwell assays were conducted. It was revealed that osteogenesis and the migration of cells were regulated by TGF-β1 via the upregulation of osteogenic and migration-associated genes. Alterations in the expression of osteogenesis- and migration-associated genes were evaluated following pre-treatment with a PI3K/AKT inhibitor (LY294002) and an mTOR/S6K1 inhibitor (rapamycin), with or without TGF-β1. The results indicated that TGF-β1 affected the osteogenesis and mineralisation of osteoblasts via the PI3K/AKT signalling pathway. Furthermore, TGF-β1 exhibited effects on mTOR/S6K1 downstream of PI3K/AKT. The present study demonstrated that TGF-β1 promoted the proliferation, differentiation and migration of human hFOB1.19 osteoblasts, and revealed that TGF-β1 affected the biological activity of osteoblasts via the PI3K/AKT/mTOR/S6K1 signalling pathway. Our findings may provide novel insight to aid the development of bone tissue engineering methods for the treatment of bone injury.

Exosomes (Exo) exhibit numerous advantages (e.g., good encapsulation, high targeting efficiency, and easy to penetrate the blood-brain barrier to the central nervous system). Exosomes are recognized as prominent carriers of mRNAs, siRNAs, miRNAs, proteins, and other bioactive molecules. As confirmed by existing studies, miR-494 is important to regulate the occurrence, progression, and repair of spinal cord injury (SCI). We constructed miR-494-modified exosomes (Exo-miR-494). As indicated from related research in vitro and vivo, Exo-miR-494 is capable of effectively inhibiting the inflammatory response and neuronal apoptosis in the injured area, as well as upregulating various anti-inflammatory factors and miR-494 to protect neurons. Moreover, it can promote the regeneration of the neurofilament and improve the recovery of behavioral function of SCI rats.

Background How to obtain a small interfering RNA (siRNA) vector has become a moot point in recent years. Exosomes (Exo) show advantages of long survival time in vivo, high transmission efficiency, and easy penetration across the blood-spinal cord barrier, renowned as excellent carriers of bioactive substances. Methods We applied mesenchymal stem cell (MSC)-derived exosomes as the delivery of synthesized siRNA, which were extracted from rat bone marrow. We constructed exosomes-siRNA (Exo-siRNA) that could specifically silence CTGF gene in the injury sites by electroporation. During the administration, we injected Exo-siRNA into the tail vein of SCI rats, Results In vivo and in vitro experiments showed that Exo-siRNA not only effectively inhibited the expressions of CTGF gene, but quenched inflammation, and thwarted neuronal apoptosis and reactive astrocytes and glial scar formation. Besides, it significantly upregulated several neurotrophic factors and anti-inflammatory factors, acting as a facilitator of locomotor recovery of rats with spinal cord injury (SCI). Conclusions In conclusion, this study has combined the thoroughness of gene therapy and the excellent drug-loading characteristics of Exo for the precise treatment of SCI, which will shed new light on the drug-loading field of Exo.