An accelerated recruitment of CFUc subpopulations after treatment with vinblastine

Granulocyte-macrophage progenitor cells (CFUc) in the bone marrow cells from mice before, and 12 hours to 7 days after intraperitoneal administration of vinblastine (VLB; 4 mg/kg) were serially investigated until day 14 of culture. The number of CFUc rose to peak levels on days 7 and 4 of culture in the whole bone marrow cells obtained before and two to four days after VLB treatment, respectively. A small peak found on day 11 of culture was marked up to 2 days after VLB treatment when fresh medium containing colony-stimulating factor was added on day 7. Each CFUc in the bone marrow cells fractionated by velocity sedimentation, counted on days 4, 7 and 11 of culture, showed distinct subpopulations of varying cell size. There was a correlation between the amount of each CFUc with cellularity and cytodifferential before and after the VLB treatment. Recruitment of stem cells through three CFUc subpopulations in the CFUc compartment is accentuated during convalescence following VLB-induced myelosuppression.