INTRODUCTION OF A SELECTABLE GENE INTO PRIMITIVE STEM CELLS CAPABLE OF LONG-TERM RECONSTITUTION OF THE HEMOPOIETIC SYSTEM OF W-W-V MICE

The random chromosomal integration sites of retrovirus vectors were used as unique clonal markers to analyze cell lineage relationships within the hemopoietic stem cell hierarchy. Using a high efficiency protocol for retrovirus-mediated gene transfer, anemic W/Wv mutant mice were reconstituted with bone marrow cells infected with a NEO vector. Analysis of the DNA from bone marrow, thymus and spleen of these reconstituted W/Wv mice indicated insertion of the vector into primitive pluripotent stem cells capable of producing both myeloid and lymphoid progeny as well as into more committed stem cells apparently restricted to either the myeloid or lymphoid lineages. The neo gene was also expressed in these mice, as they contained a variety of G418 [2-amino-2,7-dideoxy-.alpha.-D-glycero-D-glucoheptopyranosyl-(1 .fwdarw. 4)-0-[3-deoxy-4-C-methyl-3-methylamino-.beta.-L-arabinopyranosyl-(1 .fwdarw. 6)]-2-deoxy-D-streptamine] resistant in vitro colony-forming cells. High-efficiency gene transfer and expression is demonstrated in primitive hemopoietic stem cells and a direct approach for analyzing the hemopoietic stem cell hierarchy is provided.