Long-term human blood cultures: application to circulating progenitor cell autografting

Peripheral blood cells collected by cytapheresis from patients with acute leukemia following induction therapy or with multiple myeloma off-therapy, were maintained in a one-stage long-term liquid culture system. The data indicate that: (1) blood-derived granulopoietic proliferation can be sustained for up to 8 weeks with generation of CFU-GM in a way similar to bone marrow cells; and (2) this normal hematopoiesis can be sustained in spite of the absence of any development of a substantial stromal adherent layer, which suggests that, unlike hematopoiesis from bone marrow, the blood-derived non-adherent cell population is a self-sustaining compartment. While autologous transplantation with peripheral progenitor cells is gaining importance as an alternative to autologous bone marrow transplantation, this study suggests that circulating progenitor cells may have a different behavior from marrow cells. This observation may be relevant to the understanding of cases of defective hematopoietic reconstitution.