Use of magnetic capture to identify elevated levels of CCL2 following intra-articular injection of monoiodoacetate in rats

Synovial fluid biomarkers help evaluate osteoarthritis (OA) development. Magnetic capture, our new magnetic nanoparticle-based technology, has proven to be effective for determining extracellular matrix fragment levels in two rat OA models. Here, the feasibility of magnetic capture for detecting monocyte chemoattractant protein-1 (MCP-1 or CCL2) is demonstrated after intra-articular injection of monoiodoacetate (MIA) in the rat knee.
Forty-eight male Lewis rats received a right hind limb, intra-articular injection of MIA (1 mg in 25 µl of saline) or 25 µl of saline. Magnetic capture and lavage were performed at 7 days after injection (n = 6 per treatment per procedure), with magnetic capture additionally performed at 14 and 28 days post-injection (n = 6 per treatment per time point). CCL2 was also assessed in serum.
Serum CCL2 levels revealed no difference between MIA and saline animals (p = 0.0851). In contrast, magnetic capture and lavage detected a significant increase of CCL2 in the MIA-injected knee, with the MIA-injected knee having elevated CCL2 compared to contralateral and saline-injected knees (p = 0.00016 (contralateral) and p = 0.00016 (saline) for magnetic capture; p = 0.00023 (contralateral) and p = 0.00049 (saline) for lavage).
Magnetic capture of CCL2 was successfully developed and applied to determine levels of CCL2 in a rat knee. Magnetic capture detected a statistically significant increase of CCL2 in MIA-injected knees compared to controls, and CCL2 levels stayed relatively stable from week 1 through week 4 post-MIA injection.

滑液生物标志物可用于评估骨关节炎（Osteoarthritis, OA）的病情进展。磁捕获（Magnetic capture）作为一种新型磁性纳米颗粒基检测技术，已被证实在两种大鼠骨关节炎模型中可有效检测细胞外基质片段水平。本研究证实，在大鼠膝关节腔内注射单碘乙酸盐（monoiodoacetate, MIA）后，磁捕获技术用于检测单核细胞趋化蛋白-1（monocyte chemoattractant protein-1, MCP-1/CCL2）的可行性。
选取48只雄性Lewis大鼠，于右侧后肢膝关节腔内分别注射单碘乙酸盐（1 mg溶于25 μl生理盐水）或25 μl生理盐水。分别于注射后7天对两组大鼠开展磁捕获与关节灌洗检测（每处理组、每检测方式各6只大鼠）；此外，额外在注射后14天与28天追加磁捕获检测（每处理组、每时间点各6只大鼠），同时对大鼠血清中的CCL2水平进行检测。
血清CCL2水平检测结果显示，MIA注射组与生理盐水对照组大鼠之间无显著统计学差异（p=0.0851）。与之相反，磁捕获与关节灌洗均检测到MIA注射侧膝关节内CCL2水平显著升高：MIA注射侧膝关节的CCL2水平显著高于对侧膝关节与生理盐水注射侧膝关节（磁捕获检测：与对侧膝关节相比p=0.00016，与生理盐水注射侧相比p=0.00016；关节灌洗检测：与对侧膝关节相比p=0.00023，与生理盐水注射侧相比p=0.00049）。
本研究成功开发并应用了针对CCL2的磁捕获检测技术，用于检测大鼠膝关节内的CCL2水平。磁捕获检测结果显示，与对照组相比，MIA注射侧膝关节内CCL2水平存在统计学意义上的显著升高，且MIA注射后1周至4周，CCL2水平维持相对稳定。