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Figure 3 SPM-labeled EOCs: interactions with magnetic fields. (A and B) Stacked confocal images obtained along the z-axis (100x magnification). EOCs are labeled with CM-DiI (red) and SPM (green) . Exposure of SPM-loaded EOCs to a degaussed stainless steel loop does not result in significant cell attraction (A) . On the contrary, in the presence of a magnetized stainless steel loop, SPM-loaded cells are rapidly cleared from the suspension and accumulate predominantly on the loop bend (B) . A green reflection from the stainless-steel loop is evident. (C and D) Nickel coating of a commercially available stent results in multiple, small, uniformly distributed magnetic domains, as shown in ferrofluid studies (C) . Presence of numerous magnetic microdomains is evident (arrows) . This translated into a more uniform coverage of the stent surface (D) . Endothelial outgrowth cells are labeled with SPM (green) . (E and F) Transmission electronic microscopy confirms uniform cytoplasmic capture of SPM microspheres (E) . Scanning electron microscopy shows early accumulation of rounded cells to the metal surface (F) . (G and H) Representative en face fluorescent microscopy images (200x magnification) from explanted coronary arteries. Local delivery of CM-DiI (red) –labeled EOCs to a non-magnetized stent containing arterial segment results in retention of cells in small numbers (G) . Local delivery is greatly enhanced in the segment that received a nickel-coated, magnetized stent before EOC delivery. Note presence of CM-diI–labeled cells along a stent strut (H) . Abbreviations as in Figure 1 .