OPTIMIZATION OF EX VIVO EXPANSION OF CORD
BLOOD STEM CELLS FOR TRANSPLANTATION
Li K, Lam AC, Li CK, Yang M, Zhang XB, Tsang KS, Yuen PMP
Department of Paediatrics, Prince of Wales
Hospital, The Chinese University of Hong Kong, Hong Kong, China
Objective: To establish a
clinically applicable culture system by investigating the use of cytokines,
serum-free media and autologous plasma for the expansion of CB cells.
Methods: Enriched CB CD34+ cells were
cultured in four media [IMDM with fetal calf serum (FCS), X-Vivo 10,
QBSF-60 and StemSpan] with four cytokine combinations [thrombopoietin
(TPO), stem cell factor (SCF), flt-3 ligand (FL) with and without granulocyte-colony stimulating
factor (G-CSF) and/or interleukin-6 (IL-6)]. The effect of autologous CB
plasma was also investigated. The read-out parameters, which included stem
and progenitor cell subsets and colony forming units, were evaluated at
days 8 and 12.
Results: QBSF-60 or StemSpan
supported high yields of early progenitors (CD34+ cells up to
64.8-fold; CD34+CD38- cells, 330-fold; CFU-GEMM,
248-fold), CFU of the myeloid (CFU-GM, 407-fold) and erythroid (BFU/CFU-E,
144-fold) lineages. The expansion of the megakaryocytic lineage was
consistently higher in X-Vivo 10 (CFU-MK, 684-fold). Autologous plasma
promoted colony formation but reduced CD34+ cells and CFU-GEMM.
The addition of G-CSF or IL-6 improved cell yields, the former being more
effective for committed progenitors.
Conclusions: Our data supported the
expansion of early and myeloid stem and progenitor cells in QBSF-60 or
StemSpan and the megakaryocytic lineage in X-Vivo-10 for 12 days in the
presence of TPO, SCF, FL and G-CSF without FCS or autologous CB plasma. The
optimized condition may be applicable to clinical expansion for the abrogation
or reduction of post-transplant cytopenia.