The potential advantages of nanoparticle drug delivery systems in chemotherapy of tuberculosis

Efficient targeting to alveolar macrophages by intratracheal administration of mannosylated liposomes in rats

The success of targeting systems to alveolar macrophages critically depends on internalization into these cells for pharmacological intervention. Direct respiratory delivery via inhalation of mannose modified liposomal carriers to alveolar macrophages is of great interest. To evaluate the targeting efficiency to alveolar macrophages by intratracheal administration of mannosylated liposomes (Man-liposomes), Man-liposomes with various ratio of mannosylated cholesterol derivatives, cholesten-5-yloxy-N-(4-((1-imino-2-D-thiomannosylethyl)amino)alkyl)formamide (Man-C4-Chol) as mannose receptor ligand were investigated with regard to their in vitro uptake in primary cultured alveolar macrophages and in vivo intratracheal administration in rats. The in vitro uptake of Man-liposomes took place in a concentration-dependent manner. The internalization of Man-liposomes with 7.5% (Man-7.5-liposomes) and 5.0% (Man-5.0-liposomes) Man-C4-Chol was considerably higher than that of Man-liposomes with 2.5% of Man-C4-Chol (Man-2.5-liposomes) and Bare-liposomes and significantly inhibited by an excess of mannan, suggesting mannose receptor-mediated endocytosis. After intratracheal administration of Man-7.5 and Man-5.0-liposomes in rats, a significantly high internalization and selective targeting to alveolar macrophages was observed. The enhanced cellular uptake in alveolar macrophages related to the mannose density of Man-liposomes was also confirmed both in vitro and in vivo confocal microscopy studies. These results demonstrate the efficient targeting to alveolar macrophages by the intratracheally administered Man-liposomes via mannose receptor-mediated endocytosis.

Nanoparticles: health effects--pros and cons

With the advent of nanotechnology, the prospects for using engineered nanomaterials with diameters of < 100 nm in industrial applications, medical imaging, disease diagnoses, drug delivery, cancer treatment, gene therapy, and other areas have progressed rapidly. The potential for nanoparticles (NPs) in these areas is infinite, with novel new applications constantly being explored. The possible toxic health effects of these NPs associated with human exposure are unknown. Many fine particles generally considered "nuisance dusts" are likely to acquire unique surface properties when engineered to nanosize and may exhibit toxic biological effects. Consequently, the nuisance dust may be transported to distant sites and could induce adverse health effects. In addition the beneficial uses of NPs in drug delivery, cancer treatment, and gene therapy may cause unintentional human exposure. Because of our lack of knowledge about the health effects associated with NP exposure, we have an ethical duty to take precautionary measures regarding their use. In this review we highlight the possible toxic human health effects that can result from exposure to ultrafine particles (UFPs) generated by anthropogenic activities and their cardiopulmonary outcomes. The comparability of engineered NPs to UFPs suggests that the human health effects are likely to be similar. Therefore, it is prudent to elucidate their toxicologic effect to minimize occupational and environmental exposure. Highlighting the human health outcomes caused by UFPs is not intended to give a lesser importance to either the unprecedented technologic and industrial rewards of the nanotechnology or their beneficial human uses.