Penetration and Uptake of Nanoparticles in 3D Tumor Spheroids.

Aleksandra Tchoryk,Paul R Gellert,Snow Stolnik,Anna Grabowska,Vincenzo Taresco,Marianne Ashford,Richard H Argent,Martin C Garnett

doi:10.1021/acs.bioconjchem.9b00136

Aleksandra Tchoryk, Paul R Gellert + Show 6 more

Open Access

https://doi.org/10.1021/acs.bioconjchem.9b00136

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Abstract

Animal models are effective for assessing tumor localization of nanosystems but difficult to use for studying penetration beyond the vasculature. Here, we have used well-characterized HCT116 colorectal cancer spheroids to study the effect of nanoparticle (NP) physicochemical properties on penetration and uptake. Incubation of spheroids with Hoechst 33342 resulted in a dye gradient, which facilitated discrimination between the populations of cells in the core and at the periphery of spheroids by flow cytometry. This approach was used to compare doxorubicin and liposomal doxorubicin (Caelyx) and a range of model poly(styrene) nanoparticles of different sizes (30 nm, 50 nm, 100 nm) and with different surface chemistries (50 nm uniform plain, carboxylated, aminated and a range of NPs and polyethylene glycol modified NPs prepared from a promising new functionalized biodegradable polymer (poly(glycerol-adipate), PGA). Unmodified poly(styrene) nanoparticles (30 nm/50 nm) were able to penetrate to the core of HCT116 spheroids more efficiently than larger poly(styrene) nanoparticles (100 nm). Surprisingly, penetration of 30 and 50 nm particles was as good as clinically relevant doxorubicin concentrations. However, penetration was reduced with higher surface charge. PGA NPs of 100 nm showed similar penetration into spheroids as 50 nm poly(styrene) nanoparticles, which may be related to polymer flexibility. PEG surface modification of polymeric particles significantly improved penetration into the spheroid core. The new model combining the use of spheroids Hoechst staining and flow cytometry was a useful model for assessing NP penetration and gives useful insights into the effects of NPs' physical properties when designing nanomedicines.

Highlights

There has been great interest in using nanoparticle systems to deliver anticancer drugs into tumors as they offer advantages such as selective accumulation at the tumor site, with potential for enhanced efficacy and reduced toxicity compared to conventional drug treatment
The extracellular matrix (ECM) is a meshwork made of collagen fibers, proteoglycans, or glycosamino glycans such as hyaluronic acid and heparan sulfate forming a highly viscous and negatively charged barrier.[9−11] These components are thought to largely prevent convective flow within the tumor matrix, meaning that molecules move through the matrix by diffusion, limiting the rate of movement of molecules and nanomaterials through the tumor tissue.[12−14] there
Certain ECM components were found to be expressed at high levels in 3D spheroids, they have the potential to establish the penetration barriers seen in vivo, thereby allowing us to study the penetration, distribution, and uptake of nanoparticles within these models.[22−25] to date, there are limited numbers of studies that employ tumor spheroids for the evaluation of nanomedicines

Summary

Introduction

There has been great interest in using nanoparticle systems to deliver anticancer drugs into tumors as they offer advantages such as selective accumulation at the tumor site, with potential for enhanced efficacy and reduced toxicity compared to conventional drug treatment. Approved for cancer, demonstrate disappointing treatment benefits in poorly vascularized tumors.[2,3] This is just the first step of reaching the target cells, and penetration through the tumor extracellular matrix (ECM) and uptake into tumor cells is at least as important. It is more difficult to achieve the resolution needed to see penetration at the cellular and tissue level, and so these models will be less useful for understanding and inappropriate for mass screening of nanodelivery systems. Certain ECM components were found to be expressed at high levels in 3D spheroids, they have the potential to establish the penetration barriers seen in vivo, thereby allowing us to study the penetration, distribution, and uptake of nanoparticles within these models.[22−25] to date, there are limited numbers of studies that employ tumor spheroids for the evaluation of nanomedicines

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