Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, Australia.
Tissue Eng Part A. 2012 May;18(9-10):920-33. doi: 10.1089/ten.TEA.2011.0088. Epub 2012 Jan 4.
Articular cartilage is organized in depth zones with phenotypically distinct subpopulations of chondrocytes that are exposed to different oxygen tensions. Despite growing evidence of the critical role for oxygen in chondrogenesis, little is known about its effect on chondrocytes from different zones. This study evaluates zonal marker expression of human articular chondrocytes from different zones under various oxygen tensions. Chondrocytes isolated from full-thickness, superficial, and middle/deep cartilage from knee replacement surgeries were expanded and redifferentiated under hypoxic (5% O(2)) or normoxic (20% O(2)) conditions. Differentiation under hypoxia increased expression of hypoxia-inducible factors 1alpha and 2alpha and accumulation of extracellular matrix, particularly in middle/deep chondrocytes, and favored re-expression of proteoglycan 4 by superficial chondrocytes compared with middle/deep cells. Zone-dependent expression of clusterin varied with culture duration. These results demonstrate that zonal chondrocytes retain important phenotypic differences during in vitro cultivation, and that these characteristics can be improved by altering the oxygen environment. However, transcript levels for pleiotrophin, cartilage intermediate layer protein, and collagen type X were similar between zones, challenging their reliability as zonal markers for tissue-engineered cartilage from osteoarthritis patients. Key factors including oxygen tension and cell source should be considered to prescribe zone-specific properties to tissue-engineered cartilage.
关节软骨在深度上组织成具有表型不同的软骨细胞亚群的区域，这些细胞亚群暴露在不同的氧张力下。尽管越来越多的证据表明氧在软骨发生中的关键作用，但对于不同区域的软骨细胞的氧的影响知之甚少。本研究评估了不同氧张力下来自不同区域的人关节软骨细胞的区域标记物表达。从膝关节置换手术的全层、浅层和中层/深层软骨中分离出的软骨细胞在低氧（5% O(2)）或常氧（20% O(2)）条件下进行扩增和再分化。低氧条件下的分化增加了缺氧诱导因子 1alpha 和 2alpha 的表达和细胞外基质的积累，特别是在中层/深层软骨细胞中，并且与中层/深层细胞相比，浅层软骨细胞更有利于蛋白聚糖 4 的重新表达。聚集蛋白的区域依赖性表达随培养时间而变化。这些结果表明，在体外培养过程中，区域软骨细胞保留了重要的表型差异，并且通过改变氧环境可以改善这些特性。然而，多效蛋白、软骨中间层蛋白和胶原 X 型的转录水平在区域之间相似，这对其作为来自骨关节炎患者的组织工程软骨的区域标记物的可靠性提出了挑战。应考虑包括氧张力和细胞来源在内的关键因素，以规定组织工程软骨的区域特异性特性。
