Abstract
We previously described the large-scale production of RBCs from hematopoietic stem cells (HSCs) of diverse sources. Our present efforts are focused to produce RBCs thanks to an unlimited source of stem cells. Human embryonic stem (ES) cells or induced pluripotent stem cell (iPS) are the natural candidates. Even if the proof of RBCs production from these sources has been done, their amplification ability is to date not sufficient for a transfusion application. In this work, our protocol of RBC production was applied to HSC isolated from fetal liver (FL) as an intermediate source between embryonic and adult stem cells. We studied the erythroid potential of FL-derived CD34+ cells. In this in vitro model, maturation that is enucleation reaches a lower level compared to adult sources as observed for embryonic or iP, but, interestingly, they (i) displayed a dramatic in vitro expansion (100-fold more when compared to CB CD34+) and (ii) 100% cloning efficiency in hematopoietic progenitor assays after 3 days of erythroid induction, as compared to 10–15% cloning efficiency for adult CD34+ cells. This work supports the idea that FL remains a model of study and is not a candidate for ex vivo RBCS production for blood transfusion as a direct source of stem cells but could be helpful to understand and enhance proliferation abilities for primitive cells such as ES cells or iPS.
Highlights
The cell therapy approach which consists of generating cultured RBC in vitro after amplification of stem cells (SC) makes sense in a context of chronic difficulties of obtaining blood supplies
In this in vitro model, maturation that is enucleation reaches a lower level compared to adult sources as observed for embryonic or iP, but, interestingly, they (i) displayed a dramatic in vitro expansion (100-fold more when compared to cord blood (CB) CD34+) and (ii) 100% cloning efficiency in hematopoietic progenitor assays after 3 days of erythroid induction, as compared to 10–15% cloning efficiency for adult CD34+ cells
We have shown the possibility to reconstitute in vitro erythropoiesis starting from very primitive stem cells [6,7,8,9,10,11,12,13], and we were the first to report the erythroid differentiation and maturation of induced pluripotent stem cell (iPS) lines into mature enucleated RBC (4% to 10% compared to 52% to 66% from human embryonic stem (ES) cell line (H1)), which synthesized functional fetal hemoglobin [9]
Summary
The cell therapy approach which consists of generating cultured RBC (cRBC) in vitro after amplification of stem cells (SC) makes sense in a context of chronic difficulties of obtaining blood supplies. Our team has established an experimental procedure to reproduce in vitro terminal erythropoiesis from adult hematopoietic stem cells (HSC) from diverse sources (peripheral blood (PB), bone marrow (BM), and cord blood (CB)) [1, 2] This protocol, using appropriate cytokines and a specific microenvironment (including stromal murine MS5 or Mesenchymal Stem Cells (MSC)) in a serum-free medium, allows HSC proliferation and terminal differentiation in mature and functional enucleated RBC containing adult haemoglobin [2]. Major advances have allowed towards the in vitro production of RBCs from diverse sources in a few years Their transfusional future will become a reality only if we are able to produce functional transfusable RBCs at a large scale. The most accessible and proliferative source of HSC in a quantitative aspect is cord blood (CB) [3]
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