背景:肌腱干/祖细胞(TSPC)衰老有助于肌腱变性和受损的肌腱修复,导致年龄相关的肌腱疾病。Ferroptosis,一种独特的依赖铁的程序性细胞死亡形式,可能参与衰老过程。然而,铁性凋亡是否在TSPC衰老和肌腱再生中起作用尚不清楚。最近的研究报道,血小板衍生的外泌体(PL-Exos)可能在肌肉骨骼再生和炎症调节方面提供显着优势。PL-Exos对TSPC衰老和肌腱再生的影响及其机制值得进一步研究。
方法:这里,我们研究了铁凋亡在TSPC衰老发病机制中的作用。PL-Exos被分离并通过TEM测定,粒度分析,蛋白质印迹和质谱鉴定。我们通过蛋白质印迹研究了PL-Exos在TSPC衰老和铁凋亡中的功能和潜在机制。实时定量聚合酶链反应,和体外免疫荧光分析。通过HE染色评估肌腱再生,Safranin-O染色,在大鼠肩袖撕裂模型中进行生物力学测试。
结果:我们发现铁凋亡与TSPCs的衰老有关。此外,PL-Exos减轻了t-BHP诱导的TSPCs的衰老表型和铁凋亡,并保留了其增殖和生腱能力。体内动物结果表明PL-Exos改善了腱-骨愈合性能和机械强度。机械上,PL-Exos激活AMPK磷酸化和下游核因子红系2相关因子2(Nrf2)/谷胱甘肽过氧化物酶4(GPX4)信号通路,导致脂质过氧化的抑制。AMPK抑制或GPX4抑制阻断PL-Exos对t-BHP诱导的铁凋亡和衰老的保护作用。
结论:结论:铁性凋亡可能在TSPC衰老中起关键作用。发现PL-Exos激活AMPK/Nrf2/GPX4抑制铁凋亡,因此导致TSPCs衰老的抑制。我们的结果为PL-Exos在抑制肌腱退变和促进肌腱再生方面的潜在应用提供了新的理论依据。
BACKGROUND: Tendon stem/progenitor cell (TSPC) senescence contributes to tendon degeneration and impaired tendon repair, resulting in age-related tendon disorders. Ferroptosis, a unique iron-dependent form of programmed cell death, might participate in the process of senescence. However, whether ferroptosis plays a role in TSPC senescence and tendon regeneration remains unclear. Recent studies reported that Platelet-derived exosomes (PL-Exos) might provide significant advantages in musculoskeletal regeneration and inflammation regulation. The effects and mechanism of PL-Exos on TSPC senescence and tendon regeneration are worthy of further study.
METHODS: Herein, we examined the role of ferroptosis in the pathogenesis of TSPC senescence. PL-Exos were isolated and determined by TEM, particle size analysis, western blot and mass spectrometry identification. We investigated the function and underlying mechanisms of PL-Exos in TSPC senescence and ferroptosis via western blot, real-time quantitative polymerase chain reaction, and immunofluorescence analysis in vitro. Tendon regeneration was evaluated by HE staining, Safranin-O staining, and biomechanical tests in a rotator cuff tear model in rats.
RESULTS: We discovered that ferroptosis was involved in senescent TSPCs. Furthermore, PL-Exos mitigated the aging phenotypes and ferroptosis of TSPCs induced by t-BHP and preserved their proliferation and tenogenic capacity. The in vivo animal results indicated that PL-Exos improved tendon-bone healing properties and mechanical strength. Mechanistically, PL-Exos activated AMPK phosphorylation and the downstream nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4) signaling pathway, leading to the suppression of lipid peroxidation. AMPK inhibition or GPX4 inhibition blocked the protective effect of PL-Exos against t-BHP-induced ferroptosis and senescence.
CONCLUSIONS: In conclusion, ferroptosis might play a crucial role in TSPC aging. AMPK/Nrf2/GPX4 activation by PL-Exos was found to inhibit ferroptosis, consequently leading to the suppression of senescence in TSPCs. Our results provided new theoretical evidence for the potential application of PL-Exos to restrain tendon degeneration and promote tendon regeneration.