Cell viability assay

Cells were cultured to 80% to 90% confluence and then starved in serum-free DMEM for 24 hours. The medium was replaced with fresh medium containing different concentrations of liraglutide and FGF21 in the presence of the platelet-derived growth factor (PDGF; 10 ng/mL). PDGF is a growth factor that is commonly used to induce the proliferation of vascular cells [²⁵]. Cell viability was analyzed using the MTS cell proliferation assay (CellTiter 96 AQueous Cell Proliferation Assay Kit, Promega Corp., Madison, WI, USA), according to the manufacturer’s protocol. Briefly, the cells were cultured for 24 hours and 20 μL/well of the MTS solution was added to the samples in 100 μL of culture medium. The cells were subsequently incubated at 37°C for 4 hours and the absorbance was measured at 490 nm using a microplate reader.