The adult human cochlea is difficult to study because viable inner-ear tissue is rarely available and postmortem samples are technically challenging to process. Supporting cells are essential for cochlear architecture, ionic and osmotic balance, synaptic stability, stress responses, and potential regenerative signaling. In this study, we aimed to evaluate the feasibility of detecting transcripts associated with cochlear supporting-cell biology in adult human cadaveric cochlear tissue.

Bilateral temporal bones were obtained from six adult cadaveric donors within 24 hours of death, yielding 12 temporal bones. One temporal bone from each donor was processed for cochlear microdissection and RNA isolation. RNA suitable for downstream analysis was recovered from five of the six processed cochlear specimens. Total RNA was treated with DNase I, converted to cDNA, and analyzed by endpoint RT-PCR for AQP4, GLAST (SLC1A3/EAAT1), TAK1 (MAP3K7), and SOX21.

All four transcripts were detected in each of the five analyzable cochlear specimens (5/5 for AQP4, 5/5 for GLAST (SLC1A3/EAAT1), 5/5 for TAK1 (MAP3K7), and 5/5 for SOX21). These findings provide preliminary molecular evidence that AQP4, GLAST (SLC1A3/EAAT1), TAK1 (MAP3K7), and SOX21 transcripts, representing biological processes related to water and osmotic homeostasis, glutamate handling, stress-response signaling, and developmental/progenitor-associated transcriptional regulation, are detectable in adult human cadaveric cochlear tissue. Because the analysis was performed on bulk cochlear tissue rather than purified supporting cells, the detected transcripts should be interpreted as supporting-cell-associated rather than supporting-cell-specific.

The study demonstrates the feasibility of RNA-based transcript detection from postmortem adult human cochlear tissue using endpoint RT-PCR and provides a foundation for future validation using quantitative RT-PCR, RNA scope, immunostaining, single-cell or single-nucleus RNA sequencing, and spatial transcriptomics.