Fig. 5.

Transfer of [¹³C]cholesterol from [¹³C]cholesterol-loaded macrophages to adjacent SMCs. [¹³C]cholesterol-loaded macrophages were plated onto a monolayer of [¹⁵N]choline-labeled SMCs (∼90 to 95% confluency). (A) NanoSIMS images (from the cell surface and the cell interior) of [¹³C]cholesterol-loaded macrophages that had been incubated with MβCD for 30 min before plating onto the SMCs. In this image, there are three macrophages with varying amounts of ¹³C enrichment (yellow arrows). (B) NanoSIMS images (from the cell surface and the cell interior) of a [¹³C]cholesterol-loaded macrophage that had not been preincubated with MβCD (yellow arrows). Cytosolic lipid droplets (LDs) (red arrows) are visible in the ¹²C¹⁴N^– images. Ratio scales were multiplied by 10,000. SEM images of the macrophages are shown to the Far Left. (Scale bars: 10 µm.) Additional images of macrophages (both MβCD-untreated and treated)) from this experiment are shown in SI Appendix, Figs. S9 and S10. (C) ¹³C/¹²C ratios (mean ± SD) in macrophage cytosolic LDs (n = 17 droplets in five regions of 40 μm × 40 μm), LDs in SMCs immediately adjacent to the macrophage (n = 158 droplets in nine regions of 40 μm × 40 μm), and LDs in distant SMCs (n = 8 droplets in one region of 40 μm × 40 μm) for images containing MβCD-treated macrophages. (D) ¹³C/¹²C ratios (mean ± SD) in macrophage cytosolic LDs (n = 179 droplets in six regions of 40 μm × 40 μm), LDs in SMCs immediately adjacent to the macrophage (n = 1,167 droplets in 9 regions of 40 μm × 40 μm), and LDs in distant SMCs (n = 368 droplets in three regions of 40 μm × 40 μm) for images containing macrophages that were not pretreated with MβCD.