Hautier Aurélie, Salentey Valérie, Aubert-Foucher Elisabeth, Bougault Carole, Beauchef Gallic, Ronzière Marie-Claire, De Sobarnitsky Sophie, Paumier Anne, Galéra Philippe, Piperno Muriel, Damour Odile, Mallein-Gerin Frédéric
Université de Lyon, Lyon F-69003, France.
Growth Factors. 2008 Aug;26(4):201-11. doi: 10.1080/08977190802242488.
Articular cartilage contains an extracellular matrix with characteristic macromolecules such as type II collagen. Because this tissue is avascular and mature chondrocytes do not proliferate, cartilage lesions have a limited capacity for healing after trauma. Autologous chondrocyte implantation (ACI) is widely used for the treatment of patients with focal damage to articular cartilage. However, this method faces a major issue: dedifferentiation of chondrocytes occurs during the long-term culture necessary for mass cell production. The aim of this study was to determine if the step of cell amplification required for ACI could benefit from the use of bone morphogenetic protein (BMP)-2, a potent regulator of chondrogenic expression. Chondrocytes were isolated from human nasal cartilage, a hyaline cartilage like articular cartilage and were serially cultured in monolayers. After one, two or three passages, BMP-2 was used to evaluate the chondrogenic potential of the dedifferentiated chondrocytes, at the gene and protein level. We found that BMP-2 can reactivate the program of chondrogenic expression in dedifferentiated chondrocytes. To gain insight into the molecular mechanisms involved in the responsiveness of chondrocytes to BMP-2, we examined the phosphorylation of Smad proteins and the interaction of the Sry-type high-mobility-group box (Sox) transcription factors with the cartilage-specific enhancer of the type II procollagen gene. Our results show that BMP-2 acts by stimulating Smad phosphorylation and by enhancing DNA-binding of the Sox transcription factors to the specific enhancer of the type II procollagen gene. Thus, this study reveals the potential use of BMP-2 as a stimulatory agent in conventional ACI strategies.
关节软骨含有一种细胞外基质，其中包含诸如II型胶原蛋白等具有特征性的大分子。由于这种组织无血管且成熟软骨细胞不增殖，软骨损伤在创伤后的愈合能力有限。自体软骨细胞植入术（ACI）被广泛用于治疗关节软骨局灶性损伤的患者。然而，这种方法面临一个主要问题：在大规模细胞生产所需的长期培养过程中，软骨细胞会发生去分化。本研究的目的是确定ACI所需的细胞扩增步骤是否可以受益于骨形态发生蛋白（BMP）-2的使用，BMP-2是软骨生成表达的一种有效调节因子。从人鼻软骨（一种类似于关节软骨的透明软骨）中分离出软骨细胞，并在单层中进行连续培养。在传代一、二或三次后，使用BMP-2在基因和蛋白质水平评估去分化软骨细胞的软骨生成潜力。我们发现BMP-2可以重新激活去分化软骨细胞中的软骨生成表达程序。为了深入了解软骨细胞对BMP-2反应性所涉及的分子机制，我们检测了Smad蛋白的磷酸化以及Sry型高迁移率族盒（Sox）转录因子与II型前胶原基因软骨特异性增强子的相互作用。我们的结果表明，BMP-2通过刺激Smad磷酸化以及增强Sox转录因子与II型前胶原基因特异性增强子的DNA结合来发挥作用。因此，本研究揭示了BMP-2作为传统ACI策略中的刺激剂的潜在用途。
