Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw, Poland.
Department of Histology and Embryology, Medical University of Warsaw, Warsaw, Poland.
Cartilage. 2021 Dec;13(2_suppl):326S-335S. doi: 10.1177/1947603520941225. Epub 2020 Jul 16.
Initial stages of cartilage matrix calcification depend on the activity of matrix vesicles. The purpose of the study was to describe how calcified matrix vesicles join into larger structures, to present their up-to-date undescribed 3-dimensional image, and to observe how calcified matrix relates to chondrocyte lacunae.
Calcified cartilage was obtained from the zone of provisional calcification of calf costochondral junctions, then enzymatically isolated and studied by microtomography, scanning electron microscopy, atomic force microscopy and X-ray diffraction, and Fourier transform infrared spectroscopy.
Hyaluronidase digestion released packets of granules surrounded by the cartilage matrix. Further digestion, with collagenase and trypsin, removed matrix and exposed granules with dimensions within 50 to 150 nm range, which we consider as equivalent of calcified matrix vesicles. Granules joined into larger groups with dimensions of 0.5 to 2 μm, which we call globular units. Certain matrix vesicles appeared well connected but contained globular units that had spaces filled with electron lucent material, presumably matrix or chondrocyte remnants. Globular units were organized into massive structures taking the shape of oval plates. Comparison of these plates with lacunae containing isogenous groups of chondrocytes from proliferative zone of costochondral junction suggests that the cells from a single lacuna were responsible for the formation of one plate. The plates were connected with each other and extended over provisional calcification zone.
The outcome showed how particular calcified matrix vesicles associate into globular units, which organize into massive structures assuming the shape of oval plates and eventually cover large areas of cartilage matrix.
软骨基质钙化的初始阶段依赖于基质小泡的活性。本研究旨在描述钙化基质小泡如何结合形成更大的结构，呈现其最新的未描述的三维图像，并观察钙化基质与软骨细胞陷窝的关系。
从小牛肋软骨结合处的临时钙化区获取钙化软骨，然后通过微断层扫描、扫描电子显微镜、原子力显微镜和 X 射线衍射以及傅里叶变换红外光谱进行酶解分离和研究。
透明质酸酶消化释放出被软骨基质包围的颗粒包。进一步用胶原酶和胰蛋白酶消化，去除基质，暴露出尺寸在 50 至 150nm 范围内的颗粒，我们认为这些颗粒相当于钙化的基质小泡。颗粒结合成 0.5 至 2μm 大小的更大的颗粒群，我们称之为球形单元。某些基质小泡似乎连接良好，但含有球形单元，其中有空隙填充着电子透明物质，可能是基质或软骨细胞的残余物。球形单元组织成椭圆形板状的大块结构。将这些板与含有来自肋软骨结合处增殖区同源群的软骨细胞的陷窝进行比较表明，来自单个陷窝的细胞负责形成一个板。这些板彼此连接，并延伸到临时钙化区。
结果表明，特定的钙化基质小泡如何结合形成球形单元，这些球形单元如何组织成块状结构，呈椭圆形板状，并最终覆盖软骨基质的大片区域。
