Ewers B J, Dvoracek-Driksna D, Orth M W, Haut R C
Orthopaedic Biomechanics Laboratory, College of Osteopathic Medicine, Michigan State University, East Lansing 48824, USA.
J Orthop Res. 2001 Sep;19(5):779-84. doi: 10.1016/S0736-0266(01)00006-7.
Mechanical loads can lead to matrix damage and chondrocyte death in articular cartilage. This damage has been implicated in the pathogenesis of secondary osteoarthritis. Studies on cartilage explants with the attachment of underlying bone at high rates of loading have documented cell death adjacent to surface lesions. On the other hand, studies involving explants removed from bone at low rates of loading suggest no clear spatial association between cell death and matrix damage. The current study hypothesized that the observed differences in the distribution of cell death in these studies are attributed to the rate of loading. Ninety bovine cartilage explants were cultured for two days. Sixty explants were loaded in unconfined compression to 40 MPa in either a fast rate of loading experiment (approximately 900 MPa/s) or a low rate of loading experiment (40 MPa/s). The remaining 30 explants served as a control population. All explants were cultured for four days after loading. Matrix damage was assessed by measuring the total length and average depth of surface lesions and the release of glycosaminoglycans to the culture media. Explants were sectioned and stained with calcein and ethidium bromide homodimer to document the number of live and dead cells. Greater matrix damage was documented in explants subjected to a high rate of loading, compared to explants exposed to a low rate of loading. The high rate of loading experiments resulted in cell death adjacent to fissures, whereas more dead cells were observed in the low rate of loading experiments and a more diffuse distribution of dead cells was observed away from the fissures. In conclusion, this study indicated that the rate of loading can significantly affect the degree of matrix damage, the distribution of dead cells, and the amount of cell death in unconfined compression experiments on explants of articular cartilage.
机械负荷可导致关节软骨的基质损伤和软骨细胞死亡。这种损伤与继发性骨关节炎的发病机制有关。对带有下方骨骼附着的软骨外植体进行高负荷率加载的研究记录了表面损伤附近的细胞死亡。另一方面，涉及以低负荷率从骨骼上取下的外植体的研究表明，细胞死亡与基质损伤之间没有明显的空间关联。当前的研究假设，这些研究中观察到的细胞死亡分布差异归因于负荷率。九十块牛软骨外植体培养两天。六十块外植体在无侧限压缩下加载至40兆帕，分别进行快速加载实验（约900兆帕/秒）或慢速加载实验（40兆帕/秒）。其余30块外植体作为对照样本。所有外植体在加载后再培养四天。通过测量表面损伤的总长度和平均深度以及糖胺聚糖向培养基中的释放来评估基质损伤。将外植体切片，用钙黄绿素和溴化乙锭同二聚体染色，以记录活细胞和死细胞的数量。与低负荷率的外植体相比，高负荷率的外植体有更严重的基质损伤。高负荷率加载实验导致裂隙附近出现细胞死亡，而在低负荷率加载实验中观察到更多死细胞，并且在远离裂隙处观察到死细胞分布更分散。总之，本研究表明，在关节软骨外植体的无侧限压缩实验中，负荷率可显著影响基质损伤程度、死细胞分布以及细胞死亡数量。
