机械应力对拇外翻足截骨端成纤维细胞外泌体的调控机制

背景:微创治疗拇外翻术后“裹帘”外固定(通过趾蹼间夹垫“8”字绷带弹性外固定实现),为截骨端愈合提供适宜的力学环境。可见应力刺激对截骨端愈合至关重要,但其机制尚未明确。目的:探索机械应力对成纤维细胞来源外泌体的调控机制。方法:取拇外翻手术取得的第1跖骨头内侧骨组织,采用组织直接贴壁培养的方法进行成纤维细胞体外培养获取传代细胞,模拟拇外翻患者术后“8”字绷带包扎法截骨端所受力学刺激,提取外泌体。利用电镜、纳米粒径追踪分析、Western blot检测外泌体大小分布、形态及外泌体标志物的差异。研究方案于2013-03-21经中国中医科学院望京医院伦理委员会批准,批准编号为2013-03-21。结果与结论:拇外翻足截骨块培养的成纤维细胞加载15%的静态拉伸作用后,分泌的外泌体增加,且外泌体中均存在CD9和CD81。2组外泌体的粒径分布范围相符,且15%的静态拉伸作用使得外泌体的浓度增高。说明15%的拉伸力有助于成纤维细胞分泌生长因子,进而有助于促进成骨细胞成骨。

Mechanism underlying mechanical stress regulating fibroblasts-derived exosomes at the osteotomized end following hallux valgus correction

BACKGROUND:Bandage internal fixation(defined as the interphalangeal insertion of“8”-shaped bandage for elastic external fixation)produces a suitable mechanical environment for bone healing after minimally invasive treatment of hallux valgus.Stress stimulation is essential for bone healing after osteotomy,but the mechanism is still unclear.OBJECTIVE:To study the regulatory mechanism of mechanical stress on fibroblasts-derived exosomes.METHODS:The medial bone tissue of the first metatarsal bone obtained in the surgery for hallux valgus was taken as a specimen.The fibroblasts were passaged in vitro via direct tissue adherent culture.The loading system provided a cell strain simulating external fixation using“8”-shaped bandage for the pressure-loading culture of hallux valgus fibroblasts,and then exosomes were extracted.Size distribution,morphology and markers of exosomes were detected by electron microscopy,nanoparticle tracking analysis and western blot assay.The study protocol was approved by the Ethics Committee of Wangjing Hospital of China Academy of Chinese Medical Sciences with approval No.2013-03-21 on March 21,2013.RESULTS AND CONCLUSION:Static stretching(15%)could promote the secretion of exosomes from fibroblasts.The expression of CD9 and CD81 was detected in the fibroblasts-derived exosomes of the control group and the experimental group.Range of exosome particle size distribution was consistent in the two groups of exosomes,and 15%static stretching increased the concentration of exosomes.This indicates that 15% static stretching helps fibroblasts secrete growth factors,which in turn contribute to osteoblast osteogenesis.