Pharmacokinetics of biologics in CNS poses significant challenges for drug developers who are limited to the use of conventional PK methods. For example, ELISA and other analytical methods lack spatial resolution, immunohistochemistry is non-quantitative and lacks longitudinality (temporal resolution), and all of these techniques (along with radiolabeling, microdialysis and CSF sampling) lack the crucial ability to clearly distinguish between (sub)cellular compartments.
Using in vivo microscopy, we have developed and validated a unique assay for brain distribution of large molecules labelled with a fluorescent tag. The labelled biologics are injected intravenously, and their re-distribution from blood flow through BBB to extra- and intracellular compartments is ratiometrically quantified in the cortical parenchyma of live animals.
- 2-3 groups (e.g., 1 placebo, 1-2 compounds or 1-2 doses)
- 4 imaging sessions (0 h – 1 h, 24 h, 72 h, 144 h)
- 1-3 imaging areas per animal
- 5-15 regions of interest (ROIs) in vessels versus 5-15 ROIs in parenchyma per imaging area
- report delivered 2-3 months after the study commencement
Options and extensions
- Intravenous or intrathecal delivery
- PK measurements in “reporter” mice expressing fluorescent protein in cells/organelles of interest (e.g., Thy1-YFP-H mice with YFP-labelled cortical principle neurons, or CX3CR1-EGFP mice with GFP-labeled micgrolia)
- PK combined with PD readouts in transgenic mice expressing a drug target (e.g., Alzheimer’s Disease model mice with Methoxy-X04-labelled Abeta plaques of Tau tangles)
Hoehlig K, Johnson K, Pryazhnikov E, Maasch C, Clemens-Smith A, Purschke W, Vauléon S, Buchner K, Jarosch F, Khiroug L, Vater A, Klussmann S. (2015) A novel CGRP-neutralizing Spiegelmer attenuates neurogenic plasma protein extravasation. Br J Pharmacol. doi: 10.1111/bph.13110. PMC free full text BJP free full text
Baghirov H, Karaman D, Viitala T, Duchanoy A, Lou YR, Mamaeva V, Pryazhnikov E, Khiroug L, de Lange Davies C, Sahlgren C, Rosenholm JM. (2016) Feasibility Study of the Permeability and Uptake of Mesoporous Silica Nanoparticles across the Blood-Brain Barrier. PLoS One 11(8): e0160705. PMID:27547955 PMC free full text
Other relevant publications:
Nhan T., Burgess A., Cho E. E., Stefanovic B., Lilge L., Hynynen K. (2013) Drug delivery to the brain by focused ultrasound induced blood-brain barrier disruption: quantitative evaluation of enhanced permeability of cerebral vasculature using two-photon microscopy. J. Control. Release 172, 274–280. PMID:24008151 PMC free full text