Madsen S H, Sondergaard B C, Bay-Jensen A-C, Karsdal M A
Nordic Bioscience, Herlev, Denmark.
Scand J Rheumatol. 2009 May-Jun;38(3):222-6. doi: 10.1080/03009740802464186.
The aim of this study was to investigate the time-dependent effect of insulin-like growth factor-I (IGF)-I on cartilage, evaluated by a novel procollagen type II N-terminal propeptide (PIINP) formation assay. This was performed in a cartilage model.
Bovine articular cartilage explants were cultured in Dulbecco's modified Eagle's medium (DMEM):F12 in the presence of 0, 0.01, 0.1, 1, 10, or 100 ng/mL of IGF-I. The viability of the chondrocytes was measured by the colorimetric Alamar blue assay. Collagen formation was assessed from the conditioned medium by the PIINP assay. Proteoglycan levels retained in the explants after 22 days of culture were extracted and measured by the sulfated glycosaminoglycan (sGAG) assay.
In the absence of stimulation, PIINP markedly decreased as a function of time (99.4%, p < 0.001). IGF-I dose-dependently stimulated collagen formation and more than 3000% (p < 0.0005) at 100 ng/mL IGF-I at day 20 compared to vehicle control (W/O). IGF-I maintained PIINP at levels comparable to that of day 1. IGF-I dose-dependently protected against proteoglycan loss.
IGF-I dose-dependently maintained cartilage formation. The current developed techniques aid the model to represent a more physiologically relevant model to test novel anabolic drugs for osteoarthritis (OA).
本研究旨在通过一种新型的II型前胶原N端前肽（PIINP）形成试验，研究胰岛素样生长因子-I（IGF）-I对软骨的时间依赖性作用。这是在软骨模型中进行的。
将牛关节软骨外植体在含有0、0.01、0.1、1、10或100 ng/mL IGF-I的杜氏改良 Eagle 培养基（DMEM）：F12中培养。通过比色法Alamar蓝试验测量软骨细胞的活力。通过PIINP试验从条件培养基中评估胶原蛋白的形成。培养22天后，从外植体中提取并通过硫酸化糖胺聚糖（sGAG）试验测量保留的蛋白聚糖水平。
在无刺激的情况下，PIINP随时间显著下降（99.4%，p<0.001）。与载体对照（无添加）相比，IGF-I在第20天以剂量依赖性方式刺激胶原蛋白形成，在100 ng/mL IGF-I时增加超过3000%（p<0.0005）。IGF-I将PIINP维持在与第1天相当的水平。IGF-I以剂量依赖性方式防止蛋白聚糖丢失。
IGF-I以剂量依赖性方式维持软骨形成。目前开发的技术有助于该模型代表一个更具生理相关性的模型，以测试用于骨关节炎（OA）的新型合成代谢药物。
