Horikawa Osamu, Nakajima Hideto, Kikuchi Toshiyuki, Ichimura Shoichi, Yamada Harumoto, Fujikawa Kyosuke, Toyama Yoshiaki
Department of Orthopaedic Surgery, National Defense Medical College, 3-2 Namiki, Tokorozawa 359-8513, Japan.
J Orthop Sci. 2004;9(1):29-36. doi: 10.1007/s00776-003-0737-4.
The chondron is the microanatomical unit composed of a chondrocyte and its pericellular microenvironment (PCME), including the pericellular matrix and capsule. In the present study, we extracted chondrons from human articular cartilages and investigated the relationship between the distribution of the matrix molecules, including type VI collagen, and the degeneration of articular cartilage. We also investigated the effects of interleukin-1beta (IL-1beta) and transforming growth factor beta-1 (TGF-beta1) on the distribution of type VI collagen in cultured chondrocytes. Chondrons were extracted by low-speed homogenization from cartilage pieces obtained from forensic autopsies and from patients with knee osteoarthritis (OA) undergoing total knee arthroplasty. Cartilage sections were classified into three groups (normal, slight degeneration, and moderate degeneration) based on the degree of degeneration according to Mankin's score. Extracted chondrons were immunostained, and the distribution of the matrix molecules, including type VI collagen, was investigated using a confocal laser scanning microscope (CLSM). The chondrocytes isolated by enzymic treatment were subjected to three-dimensional culture in agarose gel and then treated with IL-1beta or TGF-beta1. The distribution of newly synthesized type VI collagen in agarose gel was also investigated using the CLSM. Type VI collagen was localized specifically within the PCME of chondrons. The volume ratio of PCME to chondrocyte (P/C ratio) was significantly higher in the moderate degeneration group than in the other two groups. The accumulation of type VI collagen around a chondrocyte was obviously increased by the addition of TGF-beta1. The P/C ratio significantly increased as the severity of the OA progressed, suggesting that type VI collagen distributed specifically in the PCME was playing a protective role for chondrocytes by maintaining the pericellular microenvironment in OA.
软骨粒是由软骨细胞及其细胞周微环境（PCME）组成的微观解剖单位，包括细胞周基质和包膜。在本研究中，我们从人关节软骨中提取软骨粒，并研究包括VI型胶原在内的基质分子分布与关节软骨退变之间的关系。我们还研究了白细胞介素-1β（IL-1β）和转化生长因子β-1（TGF-β1）对培养软骨细胞中VI型胶原分布的影响。通过低速匀浆从法医尸检获得的软骨块以及接受全膝关节置换术的膝骨关节炎（OA）患者的软骨中提取软骨粒。根据Mankin评分的退变程度，将软骨切片分为三组（正常、轻度退变和中度退变）。对提取的软骨粒进行免疫染色，并使用共聚焦激光扫描显微镜（CLSM）研究包括VI型胶原在内的基质分子的分布。通过酶处理分离的软骨细胞在琼脂糖凝胶中进行三维培养，然后用IL-1β或TGF-β1处理。还使用CLSM研究了琼脂糖凝胶中新合成的VI型胶原的分布。VI型胶原特异性定位于软骨粒的PCME内。中度退变组的PCME与软骨细胞的体积比（P/C比）显著高于其他两组。添加TGF-β1后，软骨细胞周围VI型胶原的积累明显增加。随着OA严重程度的进展，P/C比显著增加，这表明特异性分布在PCME中的VI型胶原通过维持OA中的细胞周微环境对软骨细胞起保护作用。
