Povýsil Ctibor, Kana Radim, Dundr Pavel, Tvrdík Daniel, Horák Martin, Vaculík Jan, Podskubka Ales, Kubes Radovan
Department of Pathology, 1st Medical Faculty, Charles University, and General University Hospital, Czech Republic.
Pathol Res Pract. 2008;204(12):883-90. doi: 10.1016/j.prp.2008.05.005. Epub 2008 Oct 15.
The aim of our study was to evaluate the occurrence of chondrocytes containing alpha-smooth muscle actin in human normal and diseased cartilage. Immunohistochemistry using monoclonal antibodies for alpha-smooth actin, muscle-specific actin, S-100 protein, CD 34, and desmin was performed on samples of human articular cartilage obtained at autopsy following sudden death, during total hip and knee replacement for osteoarthritis, or after femoral neck fracture in patients without symptoms of osteoarthritis. Moreover, the layers of residual cartilage from chondral posttraumatic defects obtained during preoperative arthroscopy and of newly formed cartilage after autologous-chondrocyte transplantation (Hyalograft C) obtained during second-look arthroscopy were also examined by immunohistochemistry and RT PCR. Our study showed that a significant percentage of articular chondrocytes express alpha-smooth muscle actin in healthy, diseased, and regenerated articular cartilage. Alpha-actin positive chondrocytes (18%) were observed predominantly in the upper zone of normal articular cartilage. By contrast, only approximately 10% of cartilage cells in the deep region stained for this contractile actin isoform. Actin-positive chondrocytes (myochondrocytes) are formed predominantly in response to injury to the osteoarthrotic cartilage, at sites of defective healing, and in newly formed cartilage after autologous chondrocyte transplantation. Fibrocartilage is present in some of these conditions, and it is known that this tissue contains chondrocytes with actin. The presence of myochondrocytes in the surface layer of normal articular cartilage indicates that this region probably plays an important role in maintaining cartilage integrity. Myochondrocytes may utilize the contractile actin isoform in manipulating the extracellular matrix of articular cartilage. It is also possible that actin-containing chondrocytes have a higher potential for regeneration in contrast to chondrocytes that do not contain this contractile material in their cytoplasm.
我们研究的目的是评估含α-平滑肌肌动蛋白的软骨细胞在人类正常及病变软骨中的出现情况。对猝死尸检获取的、骨关节炎患者全髋关节和膝关节置换术中获取的、或股骨颈骨折且无骨关节炎症状患者术后获取的人类关节软骨样本，使用针对α-平滑肌肌动蛋白、肌肉特异性肌动蛋白、S-100蛋白、CD34和结蛋白的单克隆抗体进行免疫组织化学检测。此外，还通过免疫组织化学和逆转录聚合酶链反应对术前关节镜检查时获取的创伤后软骨缺损残留软骨层，以及二次关节镜检查时获取的自体软骨细胞移植（Hyalograft C）后新形成的软骨进行检测。我们的研究表明，在健康、病变及再生的关节软骨中，有相当比例的关节软骨细胞表达α-平滑肌肌动蛋白。α-肌动蛋白阳性软骨细胞（18%）主要见于正常关节软骨的上层区域。相比之下，深层区域仅有约10%的软骨细胞对这种收缩性肌动蛋白异构体呈阳性染色。肌动蛋白阳性软骨细胞（肌软骨细胞）主要在骨关节炎软骨损伤处、愈合缺陷部位以及自体软骨细胞移植后的新形成软骨中形成。在其中一些情况下会出现纤维软骨，且已知该组织含有含肌动蛋白的软骨细胞。正常关节软骨表层存在肌软骨细胞表明该区域可能在维持软骨完整性方面发挥重要作用。肌软骨细胞可能利用收缩性肌动蛋白异构体来操控关节软骨的细胞外基质。与细胞质中不含这种收缩性物质的软骨细胞相比，含肌动蛋白的软骨细胞也可能具有更高的再生潜力。
