Unraveling Mesenchymal Stem Cells' Dynamic Secretome Through Nontargeted Proteomics Profiling

The modulatory and regenerative potential shown by the use of MSC secretomes has emphasized the importance of their proteomics profiling. Proteomic analysis, initially focused on the targeted analysis of some candidate proteins or the identification of the secreted proteins, has been changing to an untargeted profiling also based on the quantitative evaluation of the secreted proteins.The study of the secretome can be accomplished through several different proteomics-based approaches; however this analysis must overcome one key challenge of secretome analysis: the low amount of secreted proteins and usually their high dilution.In this chapter, a general workflow for the untargeted proteomic profile of MSC's secretome is presented, in combination with a comprehensive description of the major techniques/procedures that can be used. Special focus is given to the main procedures to obtain the secreted proteins, from secretome concentration by ultrafiltration to protein precipitation. Lastly, different proteomics-based approaches are presented, emphasizing alternative digestion techniques and available mass spectrometry-based quantitative methods.