Selection and properties for the recognition of P19 embryonic carcinoma stem cells.

The P19 cell is a pluripotent stem cell of murine teratocarcinoma. When treated with retinoic acid, P19 cells can be differentiated along a neural cell lineage in culture. To isolate peptides that bind to the stem cell, we employed a phage display technology with undifferentiated P19 cells as the target. To reduce nonspecific binding of phages to the cell surface, the phage libraries were preadsorbed to the differentiated P19 cells before each selection on the undifferentiated P19 cells. After eight rounds of the selection, No. 28 phage displaying ALPSTSSQMPQL-peptide was isolated. Immunofluorescence analysis revealed that No. 28 phage selectively binds to the undifferentiated P19 cells but not to the differentiated P19 cells or SHSY cell line. The chemically synthesized peptide ALPSTSSQMPQL presented on the No. 28 phage efficiently inhibited the binding of No. 28 phage to the undifferentiated P19 cells. This result confirmed that No. 28 phage binding to the cell was mediated by the displayed peptide. The identified peptide may be targeted to a marker expressed on the stem cell and thus become a practical tool for the isolation of somatic stem cells.