Berni Matteo, Fantoni Simone, Fognani Roberta, Cardarelli Paolo, Baruffaldi Fabio, Baleani Massimiliano
Laboratorio di Tecnologia Medica, IRCCS Istituto Ortopedico Rizzoli, 40136 Bologna, Italy.
Division of Ferrara, Istituto Nazionale di Fisica Nucleare (INFN), 44122 Ferrara, Italy.
Materials (Basel). 2025 Jun 21;18(13):2943. doi: 10.3390/ma18132943.
X-ray imaging of articular cartilage could be a breakthrough for the early diagnosis of tissue degeneration. This approach relies on radiopaque contrast agents to enhance the visualization of soft tissues. The potential impact of contrast agents on the mechanical response of articular cartilage should be considered in the frame of both clinical and research applications. Attention has been drawn to a solution containing molecules with six iodine atoms and four positive charges (CA4+), which has been shown to improve the X-ray visibility of articular cartilage. This study aimed to determine the effects of a CA4+ solution on tissues' mechanical properties. An experimental pipeline based on indentation tests was applied to paired samples of articular cartilage before and after the immersion in either CA4+ or phosphate-buffered saline solution, maintained at a temperature of 22 ± 2 °C, for 22 h to determine the differences in instantaneous, viscous, and equilibrium responses between the articular cartilage of the two groups. The 22 h immersion of articular cartilage in either CA4+ or phosphate-buffered saline solution had a significant detrimental effect on the overall response, including the instantaneous, viscous, and equilibrium responses, of the articular cartilage. However, this detrimental effect was greater with exposure to the CA4+ solution. Specifically, the articular cartilage was found to be less stiff in both the instantaneous response (approximately -25%) and the equilibrium response (approximately -38%). The softening effect could be attributable to an alteration of the interaction between the proteoglycans of articular cartilage, induced by the positive charges within the CA4+ contrast agent. Further investigations are needed to elucidate whether this hypothesized mechanism is reversible.
关节软骨的X射线成像可能成为组织退变早期诊断的一项突破。这种方法依靠不透射线的造影剂来增强软组织的可视化。在临床和研究应用中，都应考虑造影剂对关节软骨力学响应的潜在影响。人们已将注意力投向一种含有六个碘原子和四个正电荷的分子的溶液（CA4+），该溶液已被证明能提高关节软骨的X射线可见度。本研究旨在确定CA4+溶液对组织力学性能的影响。基于压痕试验的实验流程应用于成对的关节软骨样本，这些样本在22±2°C的温度下分别浸泡在CA4+溶液或磷酸盐缓冲盐溶液中22小时，以确定两组关节软骨在瞬时、粘性和平衡响应方面的差异。将关节软骨在CA4+溶液或磷酸盐缓冲盐溶液中浸泡22小时，对关节软骨的整体响应，包括瞬时、粘性和平衡响应，均有显著的不利影响。然而，接触CA4+溶液时这种不利影响更大。具体而言，发现关节软骨在瞬时响应（约-25%）和平衡响应（约-38%）中都变得不那么僵硬。这种软化效应可能归因于CA4+造影剂中的正电荷引起的关节软骨蛋白聚糖之间相互作用的改变。需要进一步研究以阐明这种假设的机制是否可逆。
