Administration of exosomes is considered an attractive cell-free approach to skeletal repair and pathological disease treatment. However, poor yield for the production technique and unexpected therapeutic efficacy of exosomes have been obstacles to their widespread use in clinical practices. Here, we report an alternative strategy to produce exosome-related vesicles with high yields and improved regenerative capability. An extrusion approach was employed to amass exosome mimetics (EMs) from human mesenchymal stem cells (hMSCs). The collected EMs had a significantly increased proportion of vesicles positive for the exosome-specific CD-63 marker compared with MSC-derived exosomes. EMs were further obtained from genetically modified hMSCs in which expression of noggin, a natural bone morphogenetic protein antagonist, was down-regulated to enhance osteogenic properties of EMs. Moreover, the administration of hMSC-EMs in conjunction with an injectable chitosan hydrogel into mouse nonhealing calvarial defects demonstrated robust bone regeneration. Importantly, mechanistic studies revealed that the enhanced osteogenesis by EMs in which noggin was suppressed was mediated via inhibition of miR-29a. These findings demonstrate the great promise of MSC-mediated EMs and modulation of small RNA signaling for skeletal regeneration and cell-free therapy.

中文翻译：

---

生成用于骨再生的小 RNA 调节的外泌体模拟物。

外泌体的施用被认为是骨骼修复和病理疾病治疗的一种有吸引力的无细胞方法。然而，外泌体的生产技术产量低和出乎意料的治疗效果一直是其在临床实践中广泛应用的障碍。在这里，我们报告了一种替代策略来生产具有高产量和改进的再生能力的外泌体相关囊泡。采用挤压方法从人类间充质干细胞 (hMSC) 中聚集外泌体模拟物 (EM)。与 MSC 衍生的外泌体相比，收集的 EM 具有显着增加的外泌体特异性 CD-63 标记阳性囊泡比例。EM 进一步从基因修饰的 hMSC 中获得，其中表达了天然骨形态发生蛋白拮抗剂 noggin，被下调以增强 EM 的成骨特性。此外，将 hMSC-EM 与可注射的壳聚糖水凝胶一起用于小鼠不愈合的颅骨缺损，证明了强大的骨再生。重要的是，机制研究表明，通过抑制头蛋白的 EMs 增强的成骨作用是介导的通过抑制 miR-29a。这些发现证明了 MSC 介导的 EM 和调节小 RNA 信号用于骨骼再生和无细胞治疗的巨大前景。