FUNCTIONAL-STUDIES OF MATURING MYELOID CELLS DURING EX-VIVO EXPANSIONFOR TREATMENT OF APLASIA - FEASIBILITY OF EX-VIVO EXPANSION FROM CRYOPRESERVED BONE-MARROW CELL SAMPLES

Ex vivo expanded CD34+ progenitor cells from fresh or cryopreserved pr imate bone marrow, induced to granulocytic differentiation with growth factors, were investigated to determine whether myeloid cells produce d in liquid cultures have the normal biologic functions needed for the treatment of patients with neutropenia following high-dose chemothera py or therapeutic or accidental radiation exposure. Human and simian ( baboons or macaques) CD34+ cells were cultured with granulocyte-colony stimulating factor (G-CSF), stem cell factor (SCF), interleukin-1 (IL -1), IL-3, and IL-6, and assessed at 14 days of culture for their capa city to respond to different functional tests. Immunostaining revealed that human ex vivo expanded cells contained myeloperoxydase (MPO, 82% +/- 8%) and lactoferrin (LF, 30% +/- 6%) in their granules. Maturatio n of cultured cells was associated with stimulated chemotactic respons iveness and respiratory burst activity (superoxide anion and hydrogen peroxide production) in expansions from human, baboon, and macaque CD3 4+ progenitor cells. Mature cells obtained from ex vivo expansion of s elected cryopreserved human bone marrow CD34+ cells presented reduced but significant functional activities (chemotactic responsiveness and hydrogen peroxide production) when compared with human peripheral bloo d neutrophils. The validation of nonhuman primate ex vivo expansion sy stems may permit their use as models of irradiation. The feasibility o f ex vivo expansion from cryopreserved bone marrow cell samples may of fer considerable opportunity for banking bone marrow for autologous tr ansfusion.