(72e) Comparing Uptake and Transport of Nanomaterials in Preclinical Blood Brain Barrier (BBB) Models Using a Layer-By-Layer Electrostatically Assembled Nanoparticle Library

Millions of patients suffer from neurological diseases and brain tumors, but current treatment options for these maladies provide only symptom management or minor improvements in survival. Development of new treatment strategies is hindered by the blood brain barrier, which excludes an estimated 95% of newly developed candidate drugs from exiting systemic circulation and entering the brain space. To address the major need to deliver therapeutics across the BBB, nanoparticle drug delivery vehicles provide a particularly promising strategy. However, there is no standardized in vitro model of the BBB to conduct high-throughput screening of nanocarrier uptake across the barrier, and it is not known how to best characterize interactions at the nano-bio interface between the cells. Here, we construct a combinatorial, layer-by-layer electrostatically assembled library of nanoparticles encompassing three core materials (liposomes, PLGA, and polystyrene) and five rationally selected outer layer surface chemistries. We then apply this library to evaluate three high-throughput methods for assessing BBB uptake and transport of nanomaterials: flow cytometry, monolayer association, and Transwell transport using the immortalized human cerebral microcapillary endothelium cell line hCMEC/D3. In parallel, we examine brain accumulation of a selected group of the nanomaterials using intravital imaging in mice. We demonstrate that core material stiffness and surface chemistry both play roles in determining the amount of nanomaterial taken up by each of the three in vitro models, but with each model displaying discrete trends. We likewise demonstrate that both of these factors govern accumulation into the brain in vivo, but that certain surface chemistries, especially hylaluronate, confer transport advantages in vivo that are not predicted by any of the in vitro models and likely result from cell surface binding properties of HA. Taken together, our data show that flow cytometry, monolayer association, and Transwell transport each provide advantages and caveats for library screening of nanomaterial uptake across the BBB, that the choice of model is dependent on the intended application of the nanomaterials undergoing development, and the importance of in vivo screening for cell and tissue interactions that may not be recapitulated in vivo.

This work is supported by Cancer Research UK grant number C42454/A28596, and we would like to acknowledge use of core facilities, especially the Microscopy, Flow Cytometry, High Throughput Sciences, and Integrated Genomics and Bioinformatics cores, in the MIT Koch Institute Swanson Biotechnology Center, which is supported by the Koch Institute Core Grant P30-CA14051 from the NCI. N.G.L. is also supported by a postdoctoral fellowship from the Ludwig Center at MIT’s Koch Institute for Integrative Cancer Research