Oil red-O stains non-adipogenic cells: a precautionary note.

Bovine adipofibroblasts, 3T3-L1 cells, L-6 myogenic cells, and sheep satellite cells were allowed to proliferate for 48 h. Oil red-O (ORO) was dissolved in three different solvents isopropanol, propylene glycol and triethyl phosphate. At 48 h, the proliferative cultures were stained with the three stains. ORO stain prepared in both propylene glycol and triethyl phosphate resulted in bright red droplets appearing in all cultures, whereas ORO dissolved in isopropanol was not taken up by any of the cells. These data suggest that certain preparations of ORO may stain cells in non-adipogenic lineages as well as undifferentiated pre-adipocytes. Caution must be exercised when choosing solvents for ORO in differentiation studies using cells of the fat/adipose lineage.