Nanoparticles and the blood brain barrier
Silke Krol
Fondazione IRCCS Istituto Neurologico “Carlo Besta”, Milan, Italy
One of the major obstacle for an effective treatment but also diagnosis of neurodegenerative diseases as well as cerebral tumors is the blood brain barrier. Recently it was that in dependence of the size gold nanoparticles stabilized by citrate entered the brain[1],[2]. The mechanism as well as the distribution within the brain structure remains still unknown.
In the present work we will show with different imaging techniques as well as in vitro primary cell culture that polyelectrolyte multilayer coated nanogold (15 nm)functionalizedwith different fluorophores were able to cross the blood brain barrier and distribute in the brain with a specific pattern. We start with in vivo tracking by near infrared time domain (NIR-TD) imaging, then ex vivox-ray tomography, confocal fluorescence microscopy and standard cell stains.The resolution goes from 0.5 mm in the whole body to 300-400 nm in confocal microscopy. Additionally we will study in in vitro primary cell culture the up-take mechanism.
We observed that 19 h after injection the nanoparticles accumulate mainly in the hippocampus, thalamus, hypothalamus, and cortex.3 The signal intensity in fluorescence microscopy and its distribution indicates an endocytotic uptake of non-negligible amounts of the albumin-coated poly-styrenesulfonate (PSS)/poly-allylamine (PAH). In vitro studies with prion proteins showed that this particle composition was most effective in prion protein aggregation inhibition.4Albumin was required to protect the endothelium of the brain from a potential toxicity of PAH5 and to trigger the passage through the blood brain barrier.Basing on these results we will propose a possible uptake mechanism for nanoparticles.Moreover the biodistribution of the coated nanoparticles throughout the complete body was determined.
With different microscopic techniques we showed that the nanoparticles accumulate in brain regions close to diseased areas in prion, Alzheimer’s and Parkinson’s disease.
[1]W. H. De Jong, W. I. Hagens, P. Krystek, M. C. Burger, A. J.A.M. Sips, R. E. Geertsma (2008) Particle size-dependent organ distribution of gold nanoparticles after intravenous administration. Biomaterials 29:1912-1919.
[2] G. Sonavane, K, Tomoda, K. Makino (2008) Biodistribution of colloidal gold nanoparticles after intravenous administration: Effect of particle size. Colloids and Surfaces B: Biointerfaces 66:274–280.
3Sousa F., Mandal S., Garrovo C., Alfonso A., Bonifacio A., Latawiec D., Menk R. H., Arfelli F., Legname G., Galla H.-J., Krol S. (2010) Functionalized Gold Nanoparticles: Detailed In Vivo Multimodal Microscopic Brain Distribution Study. Nanoscale, 2, 2826-2834.
4Tran H. N. A., Sousa F., Moda F., Mandal S., Chanana M., Vimercati C., Morbin M., Krol S., Tagliavini F., Legname G. (2010) A novel class of potential prion drugs: preliminary in vitro and in vivo data for multilayer coated gold nanoparticles. Nanoscale 2, 2724-2732.
5 Chanana M., Gliozzi A., Diaspro A., Chodnevskaja I., Huewel S., Moskalenko V., Ulrichs K., Galla H.-J., Krol S. (2005) Interaction of polyelectrolytes and their composites with living cells. NanoLetters 5(12), 2605-2612