A novel role for proteomics in the discovery of cell-surface markers on stem cells: Scratching the surface.

The concept of cell-based therapy has been advocated as a novel approach for treating diseases or conditions where regeneration of cells, tissue and/or potentially organs is required. A promising source for cell-replacement therapies is provided by stem cells, but the success of this approach will ultimately rely on the ability to isolate primary stem or progenitor cells. Cell-surface protein markers will play a critical role in this step. Current methodologies for the identification of cell-surface protein markers rely primarily on antibody availability and flow cytometry, but many cell-surface proteins remain undetectable. Proteomic technologies now offer the possibility to specifically identify and investigate the cell-surface subproteome in a quantitative and discovery-driven manner. Once a cell surface protein marker panel has been identified by MS and the antibodies become available, the panel should permit the identification, tracking, and/or isolation of stem or progenitor cells that may be appropriate for therapeutics. This review provides a context for the use of proteomics in discovering new cell-surface markers for stem cells.