2.4. Oil Red O Staining

rAD-MSCs were seeded in 24 mm poly-l-lysine-coated coverslips. After differentiation into adipocytes, adipogenic induction medium was removed and the cells were washed thrice with PBS. Cells were fixed in 10% formaldehyde for 30 min at room temperature and washed thrice with distilled water. Distilled water was then removed from the coverslips, and 500 μL of Oil Red O working solution (from 3 mL of stock solution, which contains 250 mg Oil Red O in 50 mL 60% triethyl phosphate, in 2 mL distilled water, and filtered through Whatman filter paper No. 1.) was added to each coverslip. Cells were stained for 10 min at room temperature and then washed thrice with distilled water. Cells were examined under the microscope, and images were captured at 10x magnifications using an Olympus CX31 microscope. For quantitation of lipid droplets, cells were extracted with 200 μL of 60% triethyl phosphate for 10 min, and absorbance was measured using Thermo Scientific Multiskan Spectrum ELISA plate reader (Thermo, Waltham, MA) at 490 nm.