Interaction with mAo cells increases ox-LDL uptake by MΦ cells. Photomicrographs of Oil Red O stained cultures without (left frames) and with (right frames) ox-LDL (50 μg/mL) exposure for 24 hours. mAo cell cultures in (A) and (B), MΦ cell cultures in (C) and (D), and MΦ/mAo cell co-cultures in (E) and (F) are shown. Scale bar = 100 μM. (G) The spectrophotometric analysis of extracted Oil Red O stain. Data are presented as mean ± standard error of the mean and are representative of three experiments each with n = 4. *Significantly different from non-ox-LDL-treated counterpart; #significantly different from MΦ cells alone under same conditions. MΦ, bone marrow-derived macrophage; mAo, mouse aorta-derived mesenchymal progenitor; OD, optical density; ox-LDL, oxidized low-density lipoprotein.