Abstract
Abstract 4810
Ex vivo expansion and manipulation of primitive hematopoietic cells has become a major goal in the experimental hematology, because of its potential relevance in the development of therapeutic strategies aimed at treating a diverse group of hematologic disorders. Osteoblasts, mesenchymal stem/progenitor cells (MSC/MPC), adipocytes, reticular cells, endothelial cells and other stromal cells, have been implicated in regulation of HSC maintenance in endosteal and perivascular niches. These niches facilitate the signaling networks that control the balance between self-renewal and differentiation.
In the present study, we evaluated and compared the effects of three different stromal feeder layers on expansion of HSPC derived from BM and cord blood (CB): BM mesenchymal stem cells (MSC), osteoblast-differentiated BM mesenchymal stem cells (Ost-MSC) and adipocyte-differentiated BM mesenchymal stem cells (Ad-MSC). BM-MSC cultures were established from plastic adherent BM cell fractions and analyzed for immunophenotype, frequency of colony forming units (CFU-F), frequency of osteo- (CFU-Ost) and adipo- (CFU-Ad) lineage progenitors. Cultures with similar clonogenity (CFU-F: 26,4 ± 4,5%) and progenitors frequency (CFU-Ost: 14,7 ± 4,5%; CFU-Ad: 13,3 ± 4,5%) were selected for co-culture experiments. All MSC were positive for stromal cell-associated markers (CD105, CD90, CD166, CD73) and negative for hematopoietic lineage cells markers (CD34, CD19, CD14, CD45). CD34+ cells were separared from BM and CB samples by magnetic cell sorting (MACS) and analyzed for CD34, CD38 and CD45 expression.
Feeder layers (MSC, Ost-MSC, Ad-MSC) were prepared in 24-well plates prior to co-culture experiments: MSCs (4×104 cells/well) were cultured for 24 h and either used for following experiments or stimulated to differentiate into either osteoblasts or adipoctes according to standard protocols. CD34+ cells (3500-10000 cells per well) were co-cultured in Stem Span media with or without a feeder layers and in the presence of cytokines (10 ng/mL Flt3-L, 10 ng/mL SCF, 10ng/mL IL-7) for 7 days. Expanded cells were analyzed for CD34, CD38 and CD45 expression.
BM- and CB-derived CD34+CD38- cells differ in their dependence of bone marrow stroma. Coctail of growth factors facilitate CB HSPC expansion irrespective of lineage differentiation of supporting MSC feeder layer. In contrast, primitive BM CD34+CD38- HSPC were able to expand only on not differentiated MSC.
No relevant conflicts of interest to declare.
Author notes
Asterisk with author names denotes non-ASH members.
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