Fluorescent Dye Labeling Changes the Biodistribution of Tumor-Targeted Nanoparticles.

Patricia Álamo,Laura Sánchez-García,Naroa Serna,Ramón Mangues,Antonio Villaverde,Ugutz Unzueta,Julieta M Sanchez,Aïda Falgàs,Isolda Casanova,Gordon A Morris,Alejandro Sánchez-Chardi,Esther Vazquez,Eric Voltà-Duràn,María Virtudes Céspedes,Victor Pallarès

doi:10.3390/pharmaceutics12111004

Abstract

Fluorescent dye labeling is a common strategy to analyze the fate of administered nanoparticles in living organisms. However, to which extent the labeling processes can alter the original nanoparticle biodistribution has been so far neglected. In this work, two widely used fluorescent dye molecules, namely, ATTO488 (ATTO) and Sulfo-Cy5 (S-Cy5), have been covalently attached to a well-characterized CXCR4-targeted self-assembling protein nanoparticle (known as T22-GFP-H6). The biodistribution of labeled T22-GFP-H6-ATTO and T22-GFP-H6-S-Cy5 nanoparticles has been then compared to that of the non-labeled nanoparticle in different CXCR4+ tumor mouse models. We observed that while parental T22-GFP-H6 nanoparticles accumulated mostly and specifically in CXCR4+ tumor cells, labeled T22-GFP-H6-ATTO and T22-GFP-H6-S-Cy5 nanoparticles showed a dramatic change in the biodistribution pattern, accumulating in non-target organs such as liver or kidney while reducing tumor targeting capacity. Therefore, the use of such labeling molecules should be avoided in target and non-target tissue uptake studies during the design and development of targeted nanoscale drug delivery systems, since their effect over the fate of the nanomaterial can lead to considerable miss-interpretations of the actual nanoparticle biodistribution.

Highlights

Appropriate biodistribution is one of the most sought properties in nanomedicine since selective drug accumulation in target tissues is expected to enhance its effectiveness and to reduce undesired side effects [1,2]
Recent studies using small molecular weight hybrid radio and fluorescent labeled tracers aimed for image guided surgery have revealed some differences in the pharmacokinetics and tissue accumulation of tracers depending on fluorescent dye composition and the spacer length [22,23,24,25]
Additional nanoparticle labeling with ATTO488 and Sulfo-Cy5 fluorescent probes was achieved by chemical conjugation through the free lysine-amine groups of the protein

Summary

Introduction

Appropriate biodistribution is one of the most sought properties in nanomedicine since selective drug accumulation in target tissues is expected to enhance its effectiveness and to reduce undesired side effects [1,2]. Being this a critical issue, the current trend in the field is to move towards active targeting strategies [3,4,5] In this sense, one of the key benefits offered by nanoscale structures is the ability to achieve a unique biodistribution pattern by the recruitment of suitable physicochemical properties and the incorporation of effective targeting elements in a single nanoparticle [5]. One of the key benefits offered by nanoscale structures is the ability to achieve a unique biodistribution pattern by the recruitment of suitable physicochemical properties and the incorporation of effective targeting elements in a single nanoparticle [5] Because of their lack of signal emission, it is generically difficult to determine the final fate of developed nanoparticles upon in vivo administration. Recent studies using small molecular weight hybrid radio and fluorescent labeled tracers aimed for image guided surgery have revealed some differences in the pharmacokinetics and tissue accumulation of tracers depending on fluorescent dye composition and the spacer length [22,23,24,25]

Methods

Results

Discussion

Conclusion