Proteomic analysis of the hydrophobic fraction of mesenchymal stem cells derived from human umbilical cord blood

Mesenchymal stem cells (MSCs) are promising candidates for cell therapy and tissue engineering, but their application has been impeded by lack of knowledge of their core biological properties. In order to identify MSC-specific proteins, the hydrophobic protein fraction was individually prepared from two different umbilical cord blood (UCB)-derived MSC populations; these were then subjected to two-dimensional (2D) gel electrophoresis and peptide mass fingerprinting matrix-assisted laser desorption/ionization (MALDI)-time of flight (TOF)-mass spectrometry (MS). Although the 2D gel patterns differed somewhat between the two samples, computer-assisted image analysis identified shared protein spots. 35 spots were reliably identified corresponding to 32 different proteins, many of which were chaperones. Based on their primary sub-cellular locations the proteins could be grouped into 6 categories: extracellular, cell surface, endoplasmic reticular, mitochondrial, cytoplasmic and cytoskeletal proteins. This map of the water-insoluble proteome may provide valuable insights into the biology of the cell surface and other compartments of human MSCs.