Contralateral spreading of substances following intratympanic nanoparticle-conjugated gentamicin injection in a rat model

Sang Yeon Lee, Jeonghyo Kim, Sangjin Oh, Gaon Jung, Ki Jae Jeong, Van Tan Tran, Dajeong Hwang, Sung Il Kim, Jae Jin Song, Myung Whan Suh, Jaebeom Lee, Ja Won Koo

Research output: Contribution to journalArticlepeer-review

Abstract

This study was performed to investigate the Eustachian tube as a potential route for contralateral spreading following intratympanic nanoparticle (NP)-conjugated gentamicin injection in a rat model. Sprague–Dawley rats were divided into three groups and substances were injected in the right ear: group 1 (fluorescent magnetic nanoparticles [F-MNPs], n = 4), group 2 (F-MNP-conjugated gentamicin [F-MNP@GM], n = 2), and control group (no injections, n = 2). T2-weighted sequences corresponding to the regions of interest at 1, 2, and 3 h after intratympanic injection were evaluated, along with immunostaining fluorescence of both side cochlea. The heterogeneous signal intensity of F-MNPs and F-MNP@GM on T2-weighted images, observed in the ipsilateral tympanum, was also detected in the contralateral tympanum in 4 out of 6 rats, recapitulating fluorescent nanoparticles in the contralateral cochlear hair cells. Computational simulations demonstrate the contralateral spreading of particles by gravity force following intratympanic injection in a rat model. The diffusion rate of the contralateral spreading relies on the sizes and surface charges of particles. Collectively, the Eustachian tube could be a route for contralateral spreading following intratympanic injection. Caution should be taken when using the contralateral ear as a control study investigating inner-ear drug delivery through the transtympanic approach.

Original languageEnglish
Article number18636
JournalScientific Reports
Volume10
Issue number1
DOIs
StatePublished - 1 Dec 2020

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