Macrophages play important roles in the immunological defense system, but at the same time they are involved in inflammatory diseases such as atherosclerosis. Therefore, imaging macrophages is critical to assessing the status of these diseases. Toward this goal, a recombinant human H chain ferritin (rHFn)-iron oxide nano composite has been investigated as an MRI contrast agent for labeling macrophages. Iron oxide nanoparticles in the form of magnetite (or maghemite) with narrow size distribution were synthesized in the interior cavity of rHFn. The composite material exhibited the R(2) relaxivity comparable to known iron oxide MRI contrast agents. Furthermore, the mineralized protein cages are readily taken up by macrophages in vitro and provide significant T2* signal loss of the labeled cells. These results encourage further investigation into the development of the rHFn-iron oxide contrast agent to assess inflammatory disease status such as macrophage-rich atherosclerotic plaques in vivo.
[Show abstract][Hide abstract] ABSTRACT: The evaluation of macrophage cell targeting ability of RGD4C-Fn in vitro and the intracellular distribution of targeted RGD4C-Fn and nontargeted (HFn) iron oxide composite particles in macrophage cells was studied. The gene encoding the human H chain ferritin (HFn) was amplified by polymerase chain reaction (PCR) for amplification. The PCR product was subsequently cloned into Ndel/BamHl restriction enzyme sites of the pET-30a(+) plasmid (Novagen) for expression of the full length proteins. The N terminus of the HFn was exposed toward the outside of the assembled ferritin cage. The results states that RGD4C-Fn iron oxide nanocomposites will enhance in vivo MR imaging capability towards macrophage-rich diseased tissue such as atherosclerotic plaques. It was clearly confirmed from EFTEM images that both of the mineralized HFn and RGD4C-Fn are accumulated within the macrophage cells, suggesting an internalization of the nanoparticles.
[Show abstract][Hide abstract] ABSTRACT: Dps-like proteins are key factors involved in the protection of prokaryotic cells from oxidative damage. They act by either oxidizing iron to prevent the formation of oxidative radicals or by forming Dps-DNA complexes to physically protect DNA. All Dps-like proteins are characterized by a common three-dimensional architecture and are found as spherical dodecamers with a hollow central cavity. Despite their structural similarities, recent biochemical and structural data have suggested different functions among members of the family that range from protection inside the cells in response to various stress signals to adhesion and virulence during bacterial infections. Moreover, the Dps-like proteins have lately attracted considerable interest in the field of nanotechnology owing to their ability to act as protein cages for iron and various other metals. A better understanding of their function and mechanism could therefore lead to novel applications in biotechnology and nanotechnology.
Cellular and Molecular Life Sciences CMLS 10/2009; 67(3):341-51. DOI:10.1007/s00018-009-0168-2 · 5.81 Impact Factor
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