In vivo visualisation of nanoparticle entry into central nervous system tissue
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Because the potential neurotoxicity of nanoparticles is a significant issue, characterisation of nanoparticle entry into the brain is essential. Here, we describe an in vivo confocal neuroimaging method (ICON) of visualising the entry of fluorescent particles into the parenchyma of the central nervous system (CNS) in live animals using the retina as a model. Rats received intravenous injections of fluorescence-labelled polybutyl cyanoacrylate nanoparticles that had been synthesised by a standard miniemulsion polymerisation process. We performed live recording with ICON from before and up to 9 days after particle injection and took photomicrographs of the retina. In addition, selective retrograde labelling of the retinal ganglion cells was achieved by stereotaxic injection of a fluorescent dye into the superior colliculus. Using ICON, we observed vascular kinetics of nanoparticles (wash-in within seconds), their passage to the retina parenchyma (within minutes) and their distribution (mainly cellular) under in vivo conditions. For the detection of cell loss—which is important for the evaluation of toxic effects—in another experiment, we semi-quantitatively analysed the selectively labelled retinal neurons. Our results suggest that the dye per se does not lead to neuronal death. With ICON, it is possible to study nanoparticle kinetics in the retina as a model of the blood-brain barrier. Imaging data can be acquired within seconds after the injection, and the long-term fate of cellular uptake can be followed for many days to study the cellular/extracellular distribution of the nanoparticles. ICON is thus an effective and meaningful tool to investigate nanoparticle/CNS interactions.
KeywordsPolybutyl cyanoacrylate nanoparticles Blood-brain barrier Blood-retina barrier In vivo confocal neuroimaging Brain
Conflict of interest
We have no conflict of interest.
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- Kreuter J (2004) Nanoparticles as drug delivery system. In: Nalwa HS (ed) Encyclopedia of nanoscience and nanotechnology, vol 7. American Scientific Publishers, New York, pp 161–180Google Scholar
- Kreuter J, Ramge P, Petrov V, Hamm S, Gelperina SE, Engelhardt B, Alyautdin R, von Briesen H, Begley DJ (2003) Direct evidence that polysorbate-80-coated poly(butylcanacrylate) nanoparticles deliver drugs ti the CNS via specific mechanisms requiring prior binding of drug to the nanoparticles. Pharm Res 20:409–416PubMedCrossRefGoogle Scholar
- Pardridge WM (ed) (1998) Introduction to the blood-brain barrier: methodology, biology and pathology. University Press, CambridgeGoogle Scholar
- Reichel A, Begley DJ, Abott NJ (2003) The blood-brain barrier: biology and research protokolls. In: Nag S (ed) Methods in molecular medicine. Humana Press, New York, pp 309–326Google Scholar