Polymeric nanoparticles targeting the CNS: between the new PVP NPs crossing the BBB and siRNA- PBCA NPs for glaucoma treatment

In the last two decades, polymeric nanoparticles such PBCA, PLGA and PLA NPs have been extensively studied for brain drug delivery due to their biodegradable and biocompatible proprieties. We now studied polymeric NPs produced from Poly-vinyl-pyrrolidone (PVP NPs) as a new nano-carrier-system and studied their ability to pass the blood-brain-barrier (BBB) after systemic administration.

Using the blood-retina-barrier (BRB) as a surrogate of the BBB, we utilized in-vivo confocal neuroimaging (ICON) for live retinal imaging and compared our results with ex-vivo wholemount retina preparation. By loading NPs with fluorescent agents and using double/triple fluorescent labeling protocols for ex-vivo wholemount retinae, we were able to observe the distribution of NPs in the vessels and the parenchyma of the retina.

PVP NPs loaded with 1, 1'-dioctadecyl-3, 3, 3', 3'-tetramethylindocarbocyanine perchlorate (DIL), a substitute for hydrophobic drugs, were found to be able to cross the BRB when linked with 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE) which accumulated in retinal tissues within 10 min after injection.

Apart from the PVP NPs, PBCA NPs was also used to study the inhibition of retinal ganglion cells apoptosis when loaded with caspase-3-siRNA after intravitreal injection. The cells survival was tracked for 21 and 41 days post- optic nerve crush (ONC) also using ICON as it allows repetitive real-time imaging for the same rat. The results have shown a lower cell death after treatment (-35%) in comparison with the control group (-56%). Furthermore, ex-vivo wholemount retina has been successfully performed to study the RGCs morphology changes on higher cellular level with better magnification.