A Facile Method to Probe the Vascular Permeability of Nanoparticles in Nanomedicine Applications

Yan Teck Ho,Giulia Adriani,Phan-Thien Nhan,Sebastian Beyer,James Chen Yong Kah,Roger D Kamm

doi:10.1038/s41598-017-00750-3

Abstract

The effectiveness of nanoparticles (NP) in nanomedicine depends on their ability to extravasate from vasculature towards the target tissue. This is determined by their permeability across the endothelial barrier. Unfortunately, a quantitative study of the diffusion permeability coefficients (Pd) of NPs is difficult with in vivo models. Here, we utilize a relevant model of vascular-tissue interface with tunable endothelial permeability in vitro based on microfluidics. Human umbilical vein endothelial cells (HUVECs) grown in microfluidic devices were treated with Angiopoietin 1 and cyclic adenosine monophosphate (cAMP) to vary the Pd of the HUVECs monolayer towards fluorescent polystyrene NPs (pNPs) of different sizes, which was determined from image analysis of their fluorescence intensity when diffusing across the monolayer. Using 70 kDa dextran as a probe, untreated HUVECs yielded a Pd that approximated tumor vasculature while HUVECs treated with 25 μg/mL cAMP had Pd that approximated healthy vasculature in vivo. As the size of pNPs increased, its Pd decreased in tumor vasculature, but remained largely unchanged in healthy vasculature, demonstrating a trend similar to tumor selectivity for smaller NPs. This microfluidic model of vascular-tissue interface can be used in any laboratory to perform quantitative assessment of the tumor selectivity of nanomedicine-based systems.

Highlights

The effectiveness of NP-based drug delivery systems depends on their ability to extravasate into the target tissue
The measurements showed size-selectivity as observed in vascular networks in vivo[38,39,40], with a mean Pd of the smaller-sized molecules (10 kDa dextran, Pd = 3.50 × 10−5 cm/s) being significantly higher (p ≤ 0.0001) than the mean Pd of the larger-sized molecules (70 kDa dextran, Pd = 2.47 × 10−5 cm/s) (Fig. 3A, with no angiopoietin 1 (Ang-1) or pCPT-cyclic adenosine monophosphate (cAMP))
With increasing pCPT-cAMP concentrations that reduce paracellular permeability, the increase in viscous drag and exclusion experienced by larger sized 70 kDa dextran could, as a result, be more significant than the one for the smaller sized 10 kDa dextran. This may explain the more pronounced decrease in permeability for larger molecular weight dextran as pCPT-cAMP treatment concentrations increase. Taken together these results show that untreated cells and 25 μg/mL pCPT-cAMP treated cells both resulted in Pd values an order higher than that reported in vivo for cancer and normal healthy vasculature, respectively

Summary

Introduction

The effectiveness of NP-based drug delivery systems depends on their ability to extravasate into the target tissue This is determined by the permeability of the endothelial barrier to the NPs which is in turn dependent on different physical attributes of the NPs. Unlike the abundance of studies that characterize cell adhesion and uptake of NPs with different shape, size and surface functionalities[8,9,10,11], much less is known about how these attributes affect NPs extravasation. Conventional in vitro assays have been used to characterize permeability, most notably the use of multi-well plates fitted with additional membrane inserts such as the Boyden chamber or transwell membrane[14] Whilst tunable, this technique provides only relative permeabilities against a reference instead of an absolute quantitative diffusional permeability coefficient[15,16,17,18,19]. In vitro or in vivo permeability models would still be required to correlate computational data

Methods

Results

Conclusion