Ronkainen A P, Fick J M, Herzog W, Korhonen R K
Department of Applied Physics, University of Eastern Finland, Kuopio FI-70211, Finland.
Department of Applied Physics, University of Eastern Finland, Kuopio FI-70211, Finland.
J Biomech. 2016 Sep 6;49(13):2882-2890. doi: 10.1016/j.jbiomech.2016.06.033. Epub 2016 Jul 1.
Relationships between cartilage structure and superficial in situ chondrocyte deformations were investigated from 6 different knee joint locations (n=10 knees). Depth dependent cartilage structure and composition were quantified with microscopic/microspectroscopic methods. Medial tibial cartilages had the lowest superficial collagen content, highest collagen orientation angle, and highest proteoglycan content in the pericellular matrix relative to that in the extracellular matrix, coupled with the largest chondrocyte deformations. In contrast, femoral groove and lateral tibial cartilages had the highest superficial collagen contents, lowest collagen orientation angles, and low normalized proteoglycan contents in the pericellular matrix, coupled with the smallest chondrocyte deformations. To study cell-tissue interactions further, observations (n=57) from all locations were pooled and a multivariable linear regression was performed. Cell width deformations (R=0.57) correlated with collagen orientation angle (standardized regression coefficient β=0.398) and collagen content (β=-0.402). Cell height deformations (R=0.52) also correlated with collagen orientation (β=-0.248) and collagen content (β=0.455). Cell volume change upon cartilage compression (R=0.41) correlated with collagen content (β=0.435) and proteoglycan content (β=0.279). In conclusion, higher collagen and proteoglycan contents combined with lower collagen orientation angle in the extracellular matrix were related to reductions in superficial chondrocyte deformations. Also, a steep gradient of proteoglycan content from the extracellular to the pericellular matrix was associated with increased cell deformation, particularly in the medial tibial plateau cartilage.
研究了来自6个不同膝关节位置（n = 10个膝关节）的软骨结构与表层原位软骨细胞变形之间的关系。采用显微镜/显微光谱法对与深度相关的软骨结构和组成进行了量化。内侧胫骨软骨的表层胶原含量最低，胶原取向角最高，相对于细胞外基质，其细胞周基质中的蛋白聚糖含量最高，同时软骨细胞变形最大。相比之下，股骨沟和外侧胫骨软骨的表层胶原含量最高，胶原取向角最低，细胞周基质中的蛋白聚糖含量归一化后较低，同时软骨细胞变形最小。为了进一步研究细胞与组织的相互作用，汇总了所有位置的观察结果（n = 57）并进行了多变量线性回归。细胞宽度变形（R = 0.57）与胶原取向角（标准化回归系数β = 0.398）和胶原含量（β = -0.402）相关。细胞高度变形（R = 0.52）也与胶原取向（β = -0.248）和胶原含量（β = 0.455）相关。软骨压缩时细胞体积变化（R = 0.41）与胶原含量（β = 0.435）和蛋白聚糖含量（β = 0.279）相关。总之，细胞外基质中较高的胶原和蛋白聚糖含量以及较低的胶原取向角与表层软骨细胞变形的减少有关。此外，从细胞外基质到细胞周基质的蛋白聚糖含量的陡峭梯度与细胞变形增加有关，特别是在内侧胫骨平台软骨中。
