Long-term support of hematopoietic progenitors by embryonic stromal cells.
Results of LTC-CFC assays are shown. All cultures were started with 5 × 104 plastic nonadherent, light-density BM cells, and the mean number of CFCs after 4 to 5 weeks of culture is shown by columns with the SD indicated. Gray columns indicate the 8 stromal clones chosen for further study. Results of individual experiments are represented by open circles. Fifty-three stromal clones and 2 control cell lines were tested. The results of only 16 clones are shown. The stromal clones not shown supported the production of fewer than 50 CFCs/104 input cells. In the absence of pre-established stromal cell feeders, no CFCs were produced. Sites of origin of clones are defined in the text. Clones derived from the tsA58transgenic embryos include UG26-2D3, UG26-1B6, GI29-2B4, AM30-3F4, GI29-2B2, UG26-3A5, EL23-2A2, AM20-1A4, AM20-1B4, AM30-3A3, and UG26-1B4. Clones derived from the LacZ transgenic embryos include AM14-1C4, EL08-1D2, UG15-1B7, UG07-1C6, and GI09-2E6.
