3.2. Effect of Andrographolide on the cell viability of differentiating suprapatellar fat pad derived mesenchymal stem cells
To investigate the effect of AG on cell viability, the MTT assay was performed by measuring mitochondrial activity. The result showed that the OD values of SPFP-MSCs were stable following treatment with AG which did not influence cell viability when it was used at concentrations between 1.56 and 12.5 µM, indicating that cytotoxicity was undetectable when the concentration of AG was less than 12.5 µM. However, AG demonstrated the ability to decrease cell viability significantly at dosages above 12.5 µM, suggesting that high concentrations of andrographolide could inhibit cell proliferation of SPFP-MSCs (Fig. 2).