Effects of low-intensity ultrasound (LIUS) on chondrogenic differentiation of synovial cells cultured on chitosan substrate

現今已證明關節滑膜裡存在有間葉幹細胞。細胞與細胞之間的聯繫對間葉幹細胞的軟骨分化非常重要。滑膜細胞養在 TCPS 上的形態是類似纖維母細胞。細胞養在幾丁聚醣基材上的時候，細胞會聚集成球。養在幾丁聚醣的細胞在低強度超音波(LIUS)刺激的環境下，細胞聚集的情形更明顯。當滑膜細胞養在 TCPS 上的情況下不會有軟骨分化，但在幾丁聚醣上成球的細胞，如 Safranin O 染色所示，有軟骨分化的傾向。再來用LIUS刺激的細胞比養在幾丁聚醣更加強糖胺聚醣的表現。在本研究裡，測軟骨分化有關的基因表現。在培養時間點前面的時候，養在幾丁聚醣上或養在幾丁聚醣加LIUS，sox9 基因表現各增加了1.8倍和2.7倍。這些結果告訴我們LIUS刺激促進滑膜細胞透過 sox9 分化成軟骨細胞。Synovial membrane has been shown to contain mesenchymal stem cells. It is very important for stem cells to control cell-cell interaction for chondrogenic induction. Synovial cells cultured on TCPS exhibit normal fibroblast-like morphology. Cells formed spheroids when cultured on chitosan-coated substrate. Cells cultured on chitosan under low-intensity ultrasound (LIUS) stimulation formed spheroids larger than that on chitosan alone. Synovial cells cultured on TCPS could not undergo chondrogenic differentiation but cells cultured on chitosan differentiated into chondrocytes due to their spheroid formation as assessed by Safranin O staining. Furthermore, LIUS (0.1 W, 1MHz, duty cycle 10 %) applied every day enhanced more GAGs expression than cultured on chitosan only. In this study, the expression of chondrogenesis marker genes was observed. Gene expression of sox9 was increased by 1.8 and 2.7 folds by cells cultured on chitosan alone and chitosan with LIUS stimulation, respectively at early stage of cell culture. These results indicate that LIUS enhances sox9 mediated chondrogenic differentiation