Targeted brain delivery of novel nanoparticles via the blood-brain barrier thiamine transporter.

摘要

Brain drug delivery is limited by the blood-brain barrier (BBB). The BBB significantly restricts water-soluble, charged and high molecular weight therapeutics to the vascular space. Multiple strategies have been employed to circumvent the BBB, including the emerging approach of nanoparticles (NPs). NPs are colloidal particles less than 1000 nM consisting of various polymers and/or surfactants.; Conflicting toxicological data are published with regard to NPs and BBB toxicity. To address this two novel NP types: emulsifying wax/Brij 78 (NPE78) and Brij 72/Tween 80 NPs (NPE72) were evaluated in vivo and in vitro (if applicable) for effect on cerebral perfusion flow, barrier integrity, permeability and tight junctional protein expression. Neither NP formulation demonstrated significant differences for cerebral perfusion flow, barrier integrity, membrane permeability, or facilitated choline transport. Further no expression changes for occludin and claudin-1 were noted with NP incubation. The NPs appear to have no effect on baseline BBB parameters.; Brain uptake of NP formulations was evaluated as potential drug carriers across the BBB. NPs were radiolabeled by entrapment of [3H]cetyl alcohol. Entrapment efficiency and release of radiolabel were evaluated. Transport of NPE78 and NPE72 across the BBB was measured by the in situ rat brain perfusion method. For both formulations, significant uptake was observed.; To target brain, we incorporated thiamine as a surface ligand on the NP. We proposed the thiamine ligand would bind the BBB thiamine transporter, and subsequently increase NPs brain distribution. Initial work appraised [ 3H]thiamine brain distribution. Thiamine influx at the BBB was shown to be via a carrier-mediated, saturable transport mechanism. Net thiamine brain accumulation was influenced by trans-stimulation efflux. The thiamine ligand was then incorporated on the surface of the [3H]NPE78 formulation. Brain distribution of the [3H]NPE78 with and without the thiamine ligand was completed similarly as previously described. The results demonstrated addition of thiamine ligands resulted in NP BBB thiamine transporter association and an increased brain distribution after 45 seconds.; This dissertation shows development of NPs that penetrate BBB without apparent toxicity. Further, the NPs can be engineered with thiamine ligands to improve brain distribution.