Evaluation of tissue-clearing techniques for intraorgan imaging of distribution of polymeric nanoparticles as drug carriers

Abstract

Objective

The development of drug delivery systems using nanocarriers requires intraorgan imaging techniques for evaluating the distribution of nanocarriers. In this study, we evaluated the tissue-clearing techniques for the imaging of polymeric nanoparticles, a nanocarrier, in the liver used as a model of pigment-rich organ in mice.

Significance

The intraorgan imaging method of polymeric nanoparticles was examined without sectioning of organ samples for evaluating the delivery efficiency in preclinical studies.

Methods

DiI-loaded polymeric nanoparticles and fluorescence-tagged tomato lectin for fluorescence labeling of liver general structures were intravenously administered to mice. Tissue-clearing treatment of the mouse liver was performed using Clear^T2, ScaleSQ(0), clearing agent comprising fructose, urea, and glycerol for imaging (FUnGI), clear unobstructed brain/body imaging cocktails and computational analysis (CUBIC), and modified CUBIC techniques. Intraorgan fluorescence imaging in the liver was performed by confocal laser microscopy.

Results

Clear^T2 treatment exhibited insufficient clearing capability in the mouse liver. Although CUBIC treatment exhibited the best clearing capability, the CUBIC caused DiI leakage. ScaleSQ(0), FUnGI, and modified CUBIC treatments exhibited better clearing capability than Clear^T2 technique while preserving the DiI. In the fluorescence imaging, the CUBIC and modified CUBIC exhibited deeper visualization than with the ScaleSQ(0) and FUnGI; however, the CUBIC led to a change in DiI distribution. The modified CUBIC enabled the deepest visualization while preserving the distribution of DiI.

Conclusion

The intraorgan imaging method was established using modified CUBIC technique by the intravenous administration of fluorescence-tagged tomato lectin for evaluating the distribution of polymeric nanoparticles in mouse pigment-rich organs.

Keywords:

• CUBIC
• deep tissue imaging
• three-dimensional imaging
• tissue distribution
• nanoparticle delivery
• confocal laser microscopy

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Correction

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article was originally published with errors, which have now been corrected in the online version. Please see Correction (http://dx.doi.org/10.1080/03639045.2020.1857087)

Additional information

Funding

This work was supported by JSPS KAKENHI [grant numbers JP17H02178, JP18K06603, and JP18K12066] provided by the Japan Society for the Promotion of Science; the Northern Advancement Center for Science and Technology (Sapporo, Japan) [grant number H29ST-ST-36]; and the Akiyama Life Science Foundation under a 2019 Grant (Sapporo, Japan). The authors are grateful to Nagai Memorial Research Scholarship from the Pharmaceutical Society of Japan.