Abstract—CD36 is one of the major receptors for oxidized low density lipoproteins belonging to macrophage (Mφ) scavenger receptor (SR) class B and is thought to play an important role in the foam cell formation from monocyte-Mφ in the atherosclerotic lesions. Although it has been hypothesized that smooth muscle cells (SMCs) may be the other origin of foam cells in vivo, supporting data are still very limited. In the present study, we have tested the expression of a variety of SRs, including CD36, in 8 lots of primary human aortic SMCs (HASMCs) explanted from 8 different donors. Functional CD36 was expressed in cultured HASMCs, and the levels of expression were widely ranged between the lots. SR class A (SR-A) was expressed abundantly in CD36-negative lots. Other Mφ markers, such as CD32 and CD68, were expressed in all lots tested. These data suggest that the cultured HASMCs gained an Mφ-like phenotype. To determine the mechanism for the above-described phenotypic change, we have tested the expression of a...