CELLS INVOLVED IN THE CAPTURE OF NANOPARTICLES IN HEMATOPOIETIC ORGANS

The affinity of nanoparticles for hematopoietic organs could be valuab le for the targeting of certain stimulating factors to those tissues, but this affinity should also be taken into account in the toxicologic al evaluation of those carriers, especially when they are loaded with antimitotic compounds such as doxorubicin. However, the cells responsi ble for the capture of the nanoparticles and their localization in the se organs is an important point to know before trying to modulate the nanoparticle's tissue distribution. Thus, we have studied, in this pap er, the capture, the localization, and the retention in the bone marro w and in the spleen of biodegradable poly(isohexyl cyanoacrylate) nano particles as well as of nonbiodegradable polystyrene nanoparticles. Th e histological localization of these nanoparticles has been completed by cytological localization with a method used in cytochemistry for th e evaluation of intracellular accumulation of various substances, such as iron deposits in bone marrow sideroblasts. These data indicate tha t, in the bone marrow, after a quick passage through the endothelium, nanoparticles were dispersed throughout in the tissue and captured by all types of phagocytizing cells. In the spleen, nanoparticles were ma inly localized in large angular capturing cells in the marginal zone o f the lymphoid follicles.