Age-related changes of gene expression in stria vascularis

Age-related hearing loss is a progressive sensorineural hearing loss that occurs as people get older. Degeneration of the organ of Corti and atrophy of the lateral wall of the scala media in the inner ear are the two primary causes. Transcriptome analysis has emerged as a powerful tool in revealing the genetic and molecular profile of a cell or a population of cells during aging in organism models, animals and humans. Comparison of transcriptomes between young and older animals have identified many common genes and pathways that are associated with aging and longevity. We used RNA-seq to examine changes in gene expression profiles of the stria vascularis between 9- and 26-month-old CBA mice. Our transcriptome analysis provides a rich resource for mechanistic studies of biological aging of stria vascularis. Overall design: CBA mice (1m, 9m, 26 m old) of either sex were used. The lateral wall of the cochlea was microdissected from the bony wall of the cochlea. The stria vascularis was microdissected from the spiral ligament using fine forceps. The stria was transferred to an enzymatic digestion medium in a small Petri dish. The enzymatic digestion medium contained 1 ml L-15 and 0.5 mg trypsin (Sigma). After 5 min incubation at room temperature, the tissue was transferred to a small plastic chamber (0.8 ml in volume) containing enzyme-free culture medium (Leibovitz's L-15, 7.35 pH, 300 mOsm). Cells from stria were separated after gentle trituration of the tissue with a small pipette. Mixed populations (marginal, intermediate and basal cells) from four cochleae from two mice were pooled to generate each sample for each age group, and three independent samples were prepared for triplicate. It is estimated that 1,000 cells were contained in each sample.