Imaging Bioluminescent Exogenous Stem Cells in the Intact Guinea Pig Cochlea

Abstract

Stem‐cell‐based therapy may be used to replace damaged or lost neurons in the cochlear nerve of patients suffering from severe‐to‐profound sensorineural hearing loss. In order to achieve functional recovery in future clinical trials, knowledge about survival of grafted cells and their differentiation into functional neurons is a prerequisite. This calls for non‐invasive in vivo visualization of cells and long‐term monitoring of their survival and fate after cochlear transplantation. We have investigated if molecular optical imaging enables visualization of exogenous cells in the intact cochlea of guinea pig cadaver heads. Transduced (stem) cells, stably co‐expressing fluorescent (copGFP) and bioluminescent (Luc2) reporter molecules, were injected into the internal auditory meatus or directly into the cochlea through the round window. After injection of the cells into the internal auditory meatus, a bright bioluminescent signal was observed in the cavum conchae of the auricle, indicating that light generated by Luc2 is passing through the tympanic membrane and the external auditory meatus. Similar results were obtained after injection of the cells through the round window membrane, either directly into the scala tympani or in Rosenthal's canal within the modiolus of the basal cochlear turn. Imaging of the auditory bulla demonstrated that the bioluminescent signal passes through the tympanic membrane and crevices in the bony wall of the bulla. After opening the auditory bulla, the bioluminescent signal was emanating from the round window. This is the first study demonstrating that bioluminescence imaging enables visualization of luciferase‐expressing cells injected into the intact guinea pig cochlea. Anat Rec, 303:427–440, 2020. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

Bioluminescence Imaging On-Chip Platforms for Non-Invasive High-Content Bioimaging

“…BLI is currently a widely regarded technique used in a variety of cell biological and pharmacological analysis. In the last years, it has been specifically optimized for noninvasive visualization of single cells in freely moving animals and also for simultaneous visualization of multicolored bioluminescent cells for in vivo deep tissue imaging in the fields of immunology and tumor research (Iwano et al, 2018;Mezzanotte et al, 2014;Schomann et al, 2020;Zambito et al, 2022). However, until now several limitations have hindered its integration onto micro-physiological systems, mostly due to limited function outputs for non-invasive fully autonomous microsystems (Moreira Teixeira and Mezzanotte, 2021).…”

A Regenerative Medicine Approach to the Treatment of Hearing, Balance, and Olfactory Disorders: What Is in the Future for Otolaryngology?

“…The areas of research covered by these papers are organized into related groups starting with a single paper that addresses historical aspects, that is, “Historical aspects of gene therapy and stem cell therapy in the treatment of hearing and balance disorders” (Van De Water, ). This is followed by a group of six papers that utilized in vitro techniques to examine stem cell growth characteristics, migratory behavior, potential for therapeutic application, and isolation of new stem cells from human inner ear tissue: that is, “Building an artificial stem cell niche: prerequisites for future 3‐D‐formation of inner ear structures toward 3D inner ear biotechnology,” (De Groot et al, ); “Imaging bioluminescent exogenous stem cells in intact guinea pig cochlea,” (Schomann et al, ); “The effect of Matrigel on a human neural progenitor dissociated sphere culture,” (Kaiser et al, ); “Isolation and characterization of mammalian otic stem cells that can differentiate into both sensory and neuronal lineages,” (Kojima et al, ); “Progenitor cells from the human inner ear,” (Senn et al, ); and “Evaluation of cilia function in rat trachea reconstructed using collagen sponge scaffold seeded with adipose tissue‐derived stem cells” (Nakamura et al, ). This series of in vitro studies is followed by a group of five papers that probe the behavior of stem cells in vivo , looking at their ability to treat hearing loss and ultrastructural character of stem cell‐initiated hair cell regeneration: that is, “Bone marrow stromal cells accelerate hearing recovery via regeneration or maintenance of cochlear fibrocytes in mouse spiral ligaments,” (Kada et al, ); “Effect of bone marrow‐derived mesenchymal stem cells on cochlear function in an experimental rat model,” (Mittal et al, ); “Transplantation and tracking of human umbilical cord mesenchymal stem cells labeled with SPIO in deaf pigs,” (Xu et al, ); “Ultrastructural characterization of stem cell‐derived replacement vestibular hair cells within ototoxin‐damaged rat utricle explants,” (Werner et al, ); and “Recent advancements in gene and stem cell‐based treatment modalities: potential applications in noise‐induced hearing loss” (Eshraghi et al, ).…”