Effect of Delta 4 expression on the development of early stem cells.

Delta 4 expression impairs the development of early stem cells (day-12 CFU-Ss and pre–CFU-Ss). (A) The CFU-C, day 12 CFU-S, and pre–CFU-S colonies were generated from the Lin⁻ bone marrow cells infected with the control viruses or the viruses carrying Delta4. The CFU-C colony numbers are the mean values (± SE) resulting from 7 independent experiments using the control viruses or the viruses carrying the full-length Delta4 (n = 2 for pMSCV; n = 5 for MigR). The average percentage of puromycin-resistant or GFP⁺colonies was 74% ± 12% for the control viruses and 76% ± 9% for the Delta4 viruses. Only puromycin-resistant or GFP⁺colonies were counted. The numbers of CFU-S colonies are the mean values (± SE) obtained from 2 independent experiments, each using 5 mice injected with 6000 Lin⁻ bone marrow cells transduced with pMSCVpac (n = 5) or MigR (n = 5) viruses. The number of GFP⁺ CFU-S colonies assayed in one experiment (data not shown) and the total number of CFU-S colonies (data shown) gave similar results. The pre–CFU-S colony numbers are the mean values (± SE) generated from the injection of 8 mice with 100 000 bone marrow cells collected from the femurs of 5 recipient mice 12 days after being injected with 6000 Lin⁻ cells infected with the pMSCVpac viruses. (B) The ratios between the number of colonies generated from the Lin⁻ bone marrow cells infected with the control viruses or the Delta4 viruses are generated from panel A. They indicate the effect of Delta4 expression on the number of colonies generated from CFU-Cs, CFU-Ss, and pre–CFU-Ss.