Isolation in a Single Step of a Highly Enriched Murine Hematopoietic Stem

A simple procedure is described for the quantitation and enrichment of murino hematopoietic cells with the capacity for long-term repopulation of lymphoid and myeloid tissues in lethally irradiated mice. To ensure detection of the most primitive marrow cells with this potential. we used a competitive assay in which female recipients were injected with male ‘test” cells and 1 to 2 x iO “cornpromised” female marrow cells with normal short-term repopulating ability, but whose long-term repopulating ability had been reduced by serial transplantation. Primitive hematopoletic cells were purified by flow cytometry and sorting based on their forward and orthogonal lightscattering properties. and Thy-i and H-2K antigen expression. Enrichment profiles for normal marrow, and marrow of mice injected with 5-fluorouracil (5-FU) four days previously. were established for each of these parameters using an in vitro assay for high proliferative potential.