背景:了解健康的关节软骨对机械负荷的反应至关重要。适度的机械负荷对软骨有积极的影响,如维持软骨稳态。机械载荷的程度由强度的组合决定,频率,和持续时间;然而,这些参数对膝关节软骨的最佳组合尚不清楚.这项研究旨在确定哪种强度组合,频率,和持续时间为体外和体内健康的膝关节软骨提供了最佳的机械负荷。
结果:在这项研究中,使用33只雄性小鼠。对从小鼠膝关节分离的软骨细胞进行不同的循环拉伸应变(CTSs),并通过测量软骨基质相关基因的表达来评估。此外,使用不同的跑步机运动对小鼠胫骨软骨的组织学特征进行了量化。将软骨细胞和小鼠分为对照组和八个干预组:高强度,高频,持续时间长;高强度,高频,持续时间短;高强度,低频,持续时间长;高强度,低频,持续时间短;低强度,高频,持续时间长;低强度,高频,持续时间短;低强度,低频,持续时间长;低强度,低频,持续时间短。在低强度CTSs中,软骨细胞通过在短时间内改变COL2A1和长时间内改变SOX9的mRNA表达而显示出合成代谢反应。此外,低强度,低频,长时间的跑步机锻炼可最大程度地减少软骨细胞肥大,并增强胫骨软骨中的聚集蛋白聚糖合成。
结论:低强度,低频,和长时间的机械负荷是健康的膝关节软骨维持体内平衡和激活合成代谢反应的最佳组合。我们的发现为运动和生活方式指导提供了重要的科学依据。
BACKGROUND: Understanding how healthy articular cartilage responds to mechanical loading is critical. Moderate mechanical loading has positive effects on the cartilage, such as maintaining cartilage homeostasis. The degree of mechanical loading is determined by a combination of intensity, frequency, and duration; however, the best combination of these parameters for knee cartilage remains unclear. This study aimed to determine which combination of intensity, frequency, and duration provides the best mechanical loading on healthy knee articular cartilage in vitro and in vivo.
RESULTS: In this study, 33 male mice were used. Chondrocytes isolated from mouse knee joints were subjected to different cyclic tensile strains (CTSs) and assessed by measuring the expression of cartilage matrix-related genes. Furthermore, the histological characteristics of mouse tibial cartilages were quantified using different treadmill exercises. Chondrocytes and mice were divided into the control group and eight intervention groups: high-intensity, high-frequency, and long-duration; high-intensity, high-frequency, and short-duration; high-intensity, low-frequency, and long-duration; high-intensity, low-frequency, and short-duration; low-intensity, high-frequency, and long-duration; low-intensity, high-frequency, and short-duration; low-intensity, low-frequency, and long-duration; low-intensity, low-frequency, and short-duration. In low-intensity CTSs, chondrocytes showed anabolic responses by altering the mRNA expression of COL2A1 in short durations and SOX9 in long durations. Furthermore, low-intensity, low-frequency, and long-duration treadmill exercises minimized chondrocyte hypertrophy and enhanced aggrecan synthesis in tibial cartilages.
CONCLUSIONS: Low-intensity, low-frequency, and long-duration mechanical loading is the best combination for healthy knee cartilage to maintain homeostasis and activate anabolic responses. Our findings provide a significant scientific basis for exercise and lifestyle instructions.