Abstract 214

Severe preterm infants represent 1% of all UK deliveries. Following birth reduced haemopoietic activity results in anaemia, neutropenia, and thrombocytopaenia. Preterm mononuclear cells show cytokine dysregulation but the in vitro response to cytokines of preterm progenitor cells has not been characterised. We investigate whether preterm cord blood cells can respond appropriately to cytokine stimulation and examine the ex vivo expansion properties of preterm umbilical cord blood (UCB).

UCB was collected after preterm (<34 wks) delivery. Low density cells were cultured without and with growth factors (HGF) including flt-3 ligand(FL), thrombopoietin (TPO), stem cell factor (SCF), interleukins 3 and 6(IL-3, IL-6), granulocyte macrophage colony stimulating factor (GM-CSF) and erythropoietin (Epo) +/- 25% autologous serum.

Total cell number expansion after 7 days was: 0.4-fold with no HGFs; 1-fold with FL and TPO; 3.7-fold with all 7 HGFs; 4.3-fold with 7 HGFs + 25% autologous serum. Expansion of erythroid (BFU-E), mixed cell(CFU-GEMM) and granulocyte macrophage (CFU-GM) colony forming cells after 7 days was respectively: 0-, 0- and 0.4-fold with no HGFs; 1.3-, 3.9-, 6.1-fold with FL and TPO; 6.3-, 14.7-, and 6.1-fold with 7 HGFs; 6.2-, 11.4- and 4.4- fold with 7 HGFs + 25% serum (mean of at least 5 experiments).

Recovery of UCB after preterm delivery is feasible and progenitor cells can be expanded ex vivo. Expanded progenitor cells could be used as an autologous transplant to abrogate the haemopoietic failure of prematurity. Whether such expanded cells would engraft within the neonatal bone marrow remains to be determined.