Ex vivo Expansion of Hematopoietic Cells and Amifostine Effects

Ryoo, Hun Mo; Bae, Sung Hwa; Hyun, Myung Soo

Abstract

BACKGROUND
The possibility of cord blood transplantation in adults was limited by the amount of cord blood that could be collected. Cord blood transplantation after ex vivo expansion with cytokines have already been tried in adults. Amifostine is a phosphorylated aminothiol that affords broad cytoprotection from the myelosuppressive effects of antineoplastic agents. The purposes of this study were to investigate expansion of progenitor and myeloid cells after ex vivo culture of mononuclear cells (MNCs) in umbilical cord blood with growth factor and characterize hematopoietic activities of amifostine.
METHODS
MNCs were cultured and ex vivo expanded into myeloid progenitors by using hematopoietic growth factors (IL-1beta, IL-3, IL-6, G-CSF, GM-CSF, SCF, EPO) which are known to stimulate differentiation and proliferation of myeloid progenitors. MNCs exposed to the appropriate amount of amifostine for 15 min were cultured in semisolid media and harvested at 24h intervals, and then apoptosis was assessed by propidium iodide staining.
RESULTS
Myeloid colonies were successfully produced from MNCs. Maximal expansion was obtained with the combination of IL-3+SCF+G-CSF+GM-CSF. SCF was thought to be the most important growth factor for expansion of myeloid progenitor. Pretreatment with amifostine for 15 min stimulated formation of hematopoietic colonies at clinically relevant concentrations ranging from 1 to 100 micrometer. Increase in colony number compare to control were comparable after pretreatment with amifostine (10micrometer), and CFU-GEMM and BFU-E were highly responsive. Further enhancement of colony was not observed after prolonging the duration of pre- incubation exposure to 1, 8 and 24 hours. Amifostine enhanced IL-1 and IL-3 induced formation of CFU-GEMM and BFU-E. Incubation of MNCs with amifostine in suspension culture increased recovery of secondary colonies. Treatment with amifostine retarded cell loss and apoptosis, and promoted cell survival at 24, 48 and 72 hours in cytokine-deficient medium.
CONCLUSION
Cord blood MNCs can be successfully expanded into myeloid progenitors by using hematopoietic growth factors. This investigation extend the previously recognized hematologic effects of amifostine, and indicate that in addition to its cytoprotective properties, amifostine is a stimulant of hematopoietic progenitor growth.