From cellular regeneration toward functional integration: a 15-year bibliometric analysis of inner ear hair cell...

Sensorineural hearing loss, affecting over 1.5 billion people worldwide, results largely from irreversible damage to inner ear hair cells-specialized mechanosensory receptor cells that mammals cannot spontaneously regenerate. While recent advances in gene therapy and stem cell biology have raised hopes for biological repair, the rapid expansion of research has made it difficult to identify overarching trends, knowledge gaps, and translational bottlenecks. This study provides the first bibliometric analysis focusing on inner ear hair cell regeneration, covering 1,035 publications identified from the Web of Science Core Collection after systematic screening. To ensure the robustness of the findings and assess the sensitivity of the findings to database choice, we performed cross-database validation using Scopus and PubMed, which revealed high overlap rates (82.65% for PubMed and 75.76% for Scopus) and consistent patterns in the non-overlapping subset, suggesting that the primary WoSCC-based findings are not qualitatively altered by the inclusion of literature from other major databases. Using VOSviewer and CiteSpace, we analyzed publication trajectories, country/institution contributions, collaboration networks, and keyword dynamics. The results reveal a sustained increase in annual output, with the United States and China emerging as the two most productive and collaboratively central countries in the global research network. Keyword burst analysis shows a temporal shift from structural characterization (early 2010s) to signaling pathways (mid-late 2010s), and more recently to pathological mechanisms and protective strategies (late 2010s-present), including synaptopathy, transplantation, protection, ototoxicity, replacement, autophagy, and disease. VOSviewer co-occurrence analysis further reveals thematic clusters centered on hair cell regeneration and signaling, ototoxic injury and protection, and gene therapy and delivery, suggesting a field expanding from basic mechanisms toward translational research. These findings demonstrate that the field has diversified from a predominant emphasis on cellular regeneration toward broader attention to functional reconstruction of the hair cell-spiral ganglion neuron synapse. This transition underscores a growing emphasis on multi-target synaptic integration and highlights an unmet need for immune-compatible, subtype-specific gene delivery systems. Overall, this analysis, supplemented by cross-database consistency checks, provides a quantitative roadmap.