Comparison of engraftment capacity of MPB CD34⁺ cells isolated in G₀ or in G₁ phase of the cell cycle. Data from four experiments are reported as the mean ± SEM. Each experiment was performed with MPB CD34⁺ cells isolated from a different donor (n = 2 to 4 animals per experiment). (A) Percentages of chimeric human CD45⁺ cells in the BM of mice transplanted 6 weeks previously with indicated numbers of G₀ or G₁CD34⁺ cells. Average chimerism was statistically higher after transplantation of G₀CD34⁺ cells than after transplantation of G₁CD34⁺ cells (P < .05, pairedt-test). (B) Numbers of human progenitor cells per 50 × 10³ BM cells 6 weeks posttransplantation in the same recipient mice. Average human progenitor output was statistically higher in G₀- versus G₁-transplanted mice (P < .05, paired t-test).