The repair of articular cartilage injuries is impeded by the avascular and non-innervated nature of cartilage. Transplantation of autologous chondrocytes has a limited ability to augment the repair process due to the highly differentiated state of chondrocytes and the risks of donor-site morbidity. Mesenchymal stem cells can undergo chondrogenesis in the presence of growth factors for cartilage defect repair. Growth and differentiation factor-5 (GDF5) plays an important role in chondrogenesis. In this study, we examined the effects of GDF5 on chondrogenesis of adipose-derived stem cells (ADSCs) and evaluate the chondrogenic potentials of GDF5 genetically engineered ADSCs using an in vitro pellet culture model. Rat ADSCs were grown as pellet cultures and treated with chondrogenic media (CM). Induction of GDF5 by an adenovirus (Ad-GDF5) was compared with exogenous supplementation of GDF5 (100 ng/ml) and transforming growth factor-beta (TGF-beta1; 10 ng/ml). The ADSCs underwent chondrogenic differentiation in response to GDF5 exposure as demonstrated by production of proteoglycan, and up-regulation of collagen II and aggrecan at the protein and mRNA level. The chondrogenic potential of a one-time infection with Ad-GDF5 was weaker than exogenous GDF5, but equal to that of TGF-beta1. Stimulation with growth factors or CM alone induced transient expression of the mRNA for collagen X, indicating a need for optimization of the CM. Our findings indicate that GDF5 is a potent inducer of chondrogenesis in ADSCs, and that ADSCs genetically engineered to express prochondrogenic growth factors, such as GDF5, may be a promising therapeutic cell source for cartilage tissue engineering.

中文翻译：

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腺病毒介导的生长和分化因子-5 的表达促进脂肪干细胞的软骨形成。

关节软骨损伤的修复受到软骨的无血管和非神经支配性质的阻碍。由于软骨细胞的高度分化状态和供体部位发病的风险，自体软骨细胞的移植增强修复过程的能力有限。间充质干细胞可以在软骨缺损修复生长因子的存在下进行软骨形成。生长和分化因子-5 (GDF5) 在软骨形成中起重要作用。在这项研究中，我们检查了 GDF5 对脂肪来源干细胞 (ADSCs) 软骨形成的影响，并使用体外颗粒培养模型评估了 GDF5 基因工程 ADSCs 的软骨形成潜力。大鼠 ADSC 以颗粒培养物的形式生长，并用软骨形成培养基 (CM) 处理。将腺病毒 (Ad-GDF5) 对 GDF5 的诱导与外源补充 GDF5 (100 ng/ml) 和转化生长因子-β (TGF-β1；10 ng/ml) 进行比较。正如蛋白多糖的产生以及蛋白质和 mRNA 水平的胶原蛋白 II 和聚集蛋白聚糖的上调所证明的，ADSCs 经历了 GDF5 暴露后的软骨分化。一次性感染 Ad-GDF5 的软骨形成潜力弱于外源性 GDF5，但与 TGF-beta1 相同。单独用生长因子或 CM 刺激会诱导 X 胶原 mRNA 的瞬时表达，表明需要优化 CM。我们的研究结果表明 GDF5 是 ADSCs 中软骨形成的有效诱导剂，并且 ADSCs 基因工程化以表达前软骨生长因子，如 GDF5，