Project description: Adipose mesenchymal stem cells (ADSCs) are fast gaining popularity in regenerative medicine for their pluripotency and relative use of collection. Currently, we are addressing the use of ADSCs in otolaryngology, for the treatment of vocal fold (VF) paralysis. VF can result from accidentally sectioning the recurrent laryngeal nerve (RLN) during thyroidectomy. This prevents closure of the upper larynx and promotes food aspiration into the lungs. Volume augmenting materials are sometimes injected in order to bring the paralyzed VF in close proximity to the counter lateral VF. The procedure is called injection medialization laryngoplasty (IML); we have recently developed a rabbit IML model for testing biological reagents in order to improve outcomes. As part of these studies ADSCs were differentiated into chondrocytes and their fate was studied in vitro and in situ. We used mass spectrometry proteomics because microarrays based gene expression platforms do not report actual protein levels. The data show protein levels in controls and chondrogenically differentiating rabbit ADSCs at 0, 14 and 28 days, analyzed using nano-flow liquid chromatography electrospray ionization tandem mass spectrometry (nLC-MS/MS).