Abstract
BackgroundAlthough cord blood (CB) offers promise for treatment of patients with high-risk hematological malignancies and immune disorders, the limited numbers of hematopoietic stem cell (HSC)/progenitor cell in a CB unit and straitened circumstances in expanding ex vivo make it quite challenging to develop the successful cell therapies.MethodsIn this study, a novel strategy has been developed to support ex vivo expansion of hematopoietic stem and progenitor cells (HSPCs) by coculture with engineered human umbilical arterial endothelial cells (HuAECs-E4orf1-GFP), which expresses E4ORF1 stably by using a retroviral system.ResultsCoculture of CD34+ hCB cells with HuAECs-E4orf1-GFP resulted in generation of considerably more total nucleated cells, CD34+CD38−, and CD34+CD38−CD90+ HSPCs in comparison with that of cytokines alone or that of coculture with human umbilical vein endothelial cells (HuVECs) after 14-day amplification. The in vitro multilineage differentiation potential and in vivo repopulating capacity of the expanded hematopoietic cells cocultured with HuAECs-E4orf1-GFP were also markedly enhanced compared with the other two control groups. DLL4, a major determinant of arterial endothelial cell (EC) identity, was associated with CD34+ hCB cells amplified on HuAECs-E4orf1-GFP.ConclusionsCollectively, we demonstrated that HuAECs acted as a permissive niche in facilitating expansion of HSPCs. Our study further implicated that the crucial factors and related pathways presented in HuAECs may give a hint to maintain self-renewal of bona fide HSCs.
Highlights
Hematopoietic stem cells (HSCs), resided at the apex of a complicated blood cellular hierarchy, can replenish themselves by self-renewal and give rise to all the other blood cells [1]
We presumably speculated that an ex vivo human umbilical arterial endothelial cell (HuAEC) vascular niche would provide intrinsic regulators contributing to the expansion of HSCs
Molecular and functional characterization of HuAECs Flow cytometric analysis was used to characterize cell surface markers on the subcultured HuAECs (Fig. 1a), showing that the HuAECs were positive for endothelial cell markers, such as CD31 and CD144, but negative for CD133 and CD45 (Fig. 1b), which suggested that the cells were free of endothelial progenitor cells (CD133+ cell population) or mature blood cells (CD45+ cell population)
Summary
Hematopoietic stem cells (HSCs), resided at the apex of a complicated blood cellular hierarchy, can replenish themselves by self-renewal and give rise to all the other blood cells [1]. There is growing evidence that endothelium plays a fundamental role in the generation of definitive HSCs and is essential for the self-renewal of HSCs in vitro or BM repopulation in vivo recently [15, 16] These observations raise the question of whether AECs within the umbilical cord are one of the niche components for HSC amplification and function maintenance. To investigate this possibility, we presumably speculated that an ex vivo human umbilical arterial endothelial cell (HuAEC) vascular niche would provide intrinsic regulators contributing to the expansion of HSCs. cord blood (CB) offers promise for treatment of patients with high-risk hematological malignancies and immune disorders, the limited numbers of hematopoietic stem cell (HSC)/progenitor cell in a CB unit and straitened circumstances in expanding ex vivo make it quite challenging to develop the successful cell therapies
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