Abstract
Live hair cells isolated from organ of Corti are easy to identify by their typical shape, while these cells in organ of Corti are hard to identify due to the presence of millions of non-hair cells. Here we report that live hair cells in organ of Corti show a remarkable capability to accumulate fluorescent FM1-43, and that this property is useful to find live hair cells not only in isolated organ of Corti but also in tissue-cultured ones. Cochlea dissected from newborn rats (2-7days) was exposed to FM1-43 and was cut in several pieces. These pieces were embedded in a thin collagen matrix and cultured in a Neurobasal medium. When viewed under a fluorescence microscope, outer and inner hair cells were clearly distinguished as cells stained with FM1-43. When the hair cells were killed with 4% PFA, FM-dye was quickly lost from the cells, indicating that FM-dye stained only live hair cells. FM1-43-stained live hair cells were present in organ of Corti cultured for 15 days in the medium without addition of any neurotrophic factor. The row-alignment of hair cells was still maintained in the culture. By contrast, gentamycin, which is known to be toxic to hair cells, eliminated FM1-43-stained hair cells within 48hour. These data indicate that FM-dye is useful to examine life and death of cochlear hair cells in culture. [Jpn J Physiol 54 Suppl:S166 (2004)]
