Adekanmbi Isaiah, Zargar Nasim, Hulley Philippa
a Institute of Biomedical Engineering, Department of Engineering Science , University of Oxford , Oxford , UK.
b Biomedical Engineering Division, School of Engineering , University of Glasgow , Glasgow , UK.
Connect Tissue Res. 2017 Mar;58(2):162-171. doi: 10.1080/03008207.2016.1198338. Epub 2016 Jun 13.
The healing process of ruptured tendons is suboptimal, taking months to achieve tissue with inferior properties to healthy tendon. Mechanical loading has been shown to positively influence tendon healing. However, high frequency low magnitude (HFLM) loads, which have shown promise in maintaining healthy tendon properties, have not been studied with in vitro injury models. Here, we present and validate an in vitro scratch tendon tissue injury model to investigate effects of HFLM loading on the properties of injured rat tail tendon fascicles (RTTFs). A longitudinal tendon tear was simulated using a needle aseptically to scratch a defined length along individual RTTFs. Tissue viability, biomechanical, and biochemical parameters were investigated before and 7 days after culture . The effects of static, HFLM (20 Hz), and low frequency (1 Hz) cyclic loading or no load were also investigated. Tendon viability was confirmed in damaged RTTFs after 7 days of culture, and the effects of a 0.77 ± 0.06 cm scratch on the mechanical property (tangent modulus) and tissue metabolism in damaged tendons were consistent, showing significant damage severity compared with intact tendons. Damaged tendon fascicles receiving HFLM (20 Hz) loads displayed significantly higher mean tangent modulus than unloaded damaged tendons (212.7 ± 14.94 v 92.7 ± 15.59 MPa), and damaged tendons receiving static loading (117.9 ± 10.65 MPa). HFLM stimulation maintained metabolic activity in 7-day cultured damaged tendons at similar levels to fresh tendons immediately following damage. Only damaged tendons receiving HFLM loads showed significantly higher metabolism than unloaded damaged tendons (relative fluorescence units -7021 ± 635.9 v 3745.1 ± 641.7). These validation data support the use of the custom-made in vitro injury model for investigating the potential of HFLM loading interventions in treating damaged tendons.
肌腱断裂后的愈合过程并不理想，需要数月时间才能形成性能低于健康肌腱的组织。机械负荷已被证明对肌腱愈合有积极影响。然而，高频低强度（HFLM）负荷虽在维持健康肌腱性能方面显示出前景，但尚未在体外损伤模型中进行研究。在此，我们展示并验证了一种体外划痕肌腱组织损伤模型，以研究HFLM负荷对损伤大鼠尾肌腱束（RTTFs）性能的影响。使用针头无菌操作模拟纵向肌腱撕裂，沿着单个RTTFs划出规定长度。在培养前和培养7天后研究组织活力、生物力学和生化参数。还研究了静态、HFLM（20Hz）和低频（1Hz）循环负荷或无负荷的影响。培养7天后，受损RTTFs中的肌腱活力得到确认。0.77±0.06cm划痕对受损肌腱机械性能（切线模量）和组织代谢的影响是一致的，与完整肌腱相比，损伤严重程度显著。接受HFLM（20Hz）负荷的受损肌腱束显示出的平均切线模量显著高于未加载的受损肌腱（212.7±14.94对92.7±15.59MPa），以及接受静态负荷的受损肌腱（117.9±10.65MPa）。HFLM刺激使培养7天的受损肌腱中的代谢活性维持在与损伤后立即的新鲜肌腱相似的水平。只有接受HFLM负荷的受损肌腱显示出比未加载的受损肌腱显著更高的代谢（相对荧光单位 -7021±635.9对
