Targeting of daunomycin using biotinylated immunoliposomes: Pharmacokinetics, tissue distribution andin vitropharmacological effects

Active targeting of brain tumors using nanocarriers

The delivery of drugs to brain tumors is limited by the presence of the blood-brain barrier (BBB) separating the blood from the cerebral parenchyma. An understanding of the specific mechanisms of the brain capillary endothelium has led to the development of various strategies to enhance the penetration of drugs into the brain tissue. Active targeting is a non-invasive approach, which consists in transporting drugs to target organs using site-specific ligands. Drug-loaded nanocarriers capable of recognizing brain capillary endothelial cells and cerebral tumoral cells have shown promising potential in oncology. Endogenous and chimeric ligands binding to carriers or receptors of the BBB have been directly or indirectly conjugated to nanocarriers. This review indexes the main targeted colloidal systems used for drug delivery to the brain. Their pharmacological behavior and their therapeutic effect are discussed.

Brain delivery property and accelerated blood clearance of cationic albumin conjugated pegylated nanoparticle

Cationic bovine serum albumin (CBSA) conjugated poly(ethyleneglycol)-poly(lactide) (PEG-PLA) nanoparticle (CBSA-NP), was designed as a novel drug carrier for brain delivery. In this paper, three formulations of CBSA-NP with different surface CBSA density as well as native bovine serum albumin conjugated nanoparticle (BSA-NP) and CBSA unconjugated pegylated nanoparticle (NP), were formulated. Their brain transcytosis across the blood-brain barrier (BBB) coculture and brain delivery in mice were investigated using 6-coumarin as fluorescent probe. By using free CBSA as specific inhibitor, it was evidenced that CBSA-NP crossed the brain capillary endothelium through absorptive mediated transcytosis. The result of transcytosis across the BBB coculture and brain delivery in mice proved that the increase of surface CBSA density of the nanoparticle enhanced the BBB permeability-surface area but decreased blood AUC. The optimized CBSA number conjugated per averaged nanoparticle was 110, with the maleimide-PEG-PLA/methoxy-PEG-PLA weight ratio 1:10, which can acquire the greatest percentage of injected dose per gram brain (%ID/g brain) by 2.3-fold compared with NP. Besides, "accelerated blood clearance phenomenon" was found through evaluating blood clearance profile of CBSA-NP post-injection of single dose or over a period of successive high doses of CBSA-NP. Understanding these issues is important for the future development of CBSA-NP as a brain delivery carrier and for the attenuation of toxicity or immunological responses to the nanodevice following a consequence of nanomedication.

Aptamer mediated siRNA delivery

Nucleic acids that bind to cells and are subsequently internalized could prove to be novel delivery reagents. An anti-prostate specific membrane antigen aptamer that has previously been shown to bind to prostate tumor cells was coupled to siRNAs via a modular streptavidin bridge. The resulting conjugates could be simply added onto cells without any further preparation, and were taken up within 30 min. The siRNA-mediated inhibition of gene expression was as efficient as observed with conventional lipid-based reagents, and was dependent upon conjugation to the aptamer. These results suggest new venues for the therapeutic delivery of siRNAs and for the development of reagents that can be used to probe cellular physiology.