Seong Hoon Bae1, Sang Hyun Kwak1, Jee Eun Yoo1, Kyu Min Kim1, Young Min Hyun2,3, Jae Young Choi1, Jinsei Jung1,3. 1. Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea. 2. Department of Anatomy, Yonsei University College of Medicine, Seoul, Korea. 3. Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.
Abstract
OBJECTIVES: Resident macrophages are well known to be present in the cochlea, but the exact patterns thereof in spiral ligaments have not been discussed in previous studies. We sought to document the distribution of macrophages in intact cochleae using three-dimensional imaging. METHODS: Cochleae were obtained from C-X3-C motif chemokine receptor 1+/GFP mice, and organ clearing was performed. Three-dimensional images of cleared intact cochleae were reconstructed using two-photon microscopy. The locations of individual macrophages were investigated using 100-μm stacked images to reduce bias. Cochlear inflammation was then induced by lipopolysaccharide (LPS) inoculation into the middle ear through the tympanic membrane. Four days after inoculation, three-dimensional images were obtained. RESULTS: Macrophages were scarce in areas adjacent to the stria vascularis, particularly the area just beneath it even though many have suspected macrophages to be abundant in this area. This finding remained consistent upon LPS-induced cochlear inflammation, despite a significant increase in the number of macrophages, compared to non-treated cochlea. CONCLUSION: Resident macrophages in spiral ligaments are scarce in areas adjacent to the stria vascularis.
OBJECTIVES: Resident macrophages are well known to be present in the cochlea, but the exact patterns thereof in spiral ligaments have not been discussed in previous studies. We sought to document the distribution of macrophages in intact cochleae using three-dimensional imaging. METHODS: Cochleae were obtained from C-X3-C motif chemokine receptor 1+/GFP mice, and organ clearing was performed. Three-dimensional images of cleared intact cochleae were reconstructed using two-photon microscopy. The locations of individual macrophages were investigated using 100-μm stacked images to reduce bias. Cochlear inflammation was then induced by lipopolysaccharide (LPS) inoculation into the middle ear through the tympanic membrane. Four days after inoculation, three-dimensional images were obtained. RESULTS: Macrophages were scarce in areas adjacent to the stria vascularis, particularly the area just beneath it even though many have suspected macrophages to be abundant in this area. This finding remained consistent upon LPS-induced cochlear inflammation, despite a significant increase in the number of macrophages, compared to non-treated cochlea. CONCLUSION: Resident macrophages in spiral ligaments are scarce in areas adjacent to the stria vascularis.
Entities:
Keywords:
Cochlea; Macrophages; Spiral Ligament of Cochlea; Stria Vascularis