Fig 1: Expression of bcl-2 (brown A–C) and semi quantitative RT PCR of bcl-2 mRNA (D). Control cochlea showed bcl-2 expression in the pillar, in the inferior portion of the outer hair cells (arrows) and neurites (A). After sound trauma there was an occasional increase in bcl-2 immunolabeling in isolated supporting cells (arrow) (B). Treatment with MSCs after sound trauma increased expression of bcl-2 in supporting cells (arrow C). Semi quantitative RT-PCR showed reduction of bcl-2 mRNA expression after sound trauma. Treatment with MSC after sound trauma showed a significant up-regulation of bcl-2 mRNA compared to both controls and sound trauma only treated animals (p = 0.003) (D).