Tympanic Membrane Wound Healing in Rats Assessed by Transcriptome Profiling

Objectives/Hypothesis: The aim of this study is to elucidate transcriptional changes that occur in response to tympanic membrane (TM) perforation in rats and to infer key genes and molecular events in the healing process. Study Design: A prospective cohort study of 393 male Sprague-Dawley (Rattus norvegicus) rats. Methods: Sprague-Dawley rats were randomly allocated into either control or perforation groups spanning a 7-day time period. Perforation groups consisted of 12-hour, 24-hour, 36-hour, 2-day, 3-day, 4-day, 5-day, six-day, and 7-day time points. The left TMs of all perforation groups were perforated and the RNA extracted at the specified time point postperforation. Subsequent analysis was performed using Agilent's 4 x 44 k whole rat genome arrays (40 in total) to assess wound-healing gene expression over a 7-day time period. Results: Over a 7-day time course and at nine time points that encompassed the wounding and progression of healing, a total of 3,262 genes were differentially expressed. In this study the transcripts most upregulated occurred at 12 hours. These were Stefin A2 (344-fold), Stefin 2 (143-fold), and Natriuretic peptide precursor type B (222-fold). Those most down-regulated also occurred at 12 hours. These were alcohol dehydrogenase 7 (13.1-fold) and gamma-butyrobetaine hydroxylase (10.4-fold). Results were validated by quantitative real-time polymerase chain reaction. Conclusions: The findings of this study provide a baseline against which to identify disease-related molecular signatures, biomarkers, and to develop new treatments for TM conditions based on molecular evidence.