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Differentiation of Monocytes into Phenotypically Distinct Macrophages After Treatment with Human Cord Blood Stem Cell (CB-SC)-Derived Exosomes
Published on: November 12, 2020
A new stem cell biology: the continuum and microvesicles.
Peter J Quesenberry1, Mark S Dooner, Laura R Goldberg
1Providence, RI.
Transactions of the American Clinical and Climatological Association
|January 11, 2013
Summary
Hematopoietic stem cells (HSCs) are not quiescent but actively cycling, challenging purification efforts. Future research should focus on defining the dynamic HSC population rather than purification.
Area of Science:
- Stem cell biology
- Hematopoiesis
- Cell cycle regulation
Background:
- Hierarchical models of stem cell biology relied on identifying quiescent cells.
- Previous models proposed dormant G0 stem cells giving rise to differentiated cells.
- Long-term repopulating hematopoietic stem cells (LT-HSCs) were thought to be a specific phenotype (lineage negative, sca-1+, C-kit+, Flk3-, CD150+).
Purpose of the Study:
- To investigate the cell cycle status of murine hematopoietic stem cells.
- To challenge the existing model of quiescent HSCs.
- To explore the impact of cell cycle and microvesicles on stem cell phenotype.
Main Methods:
- Tritiated thymidine suicide assays.
- Pyronin-Hoechst fluorescent-activated cell sorting (FACS) separations.
- In vivo bromodeoxyuridine (BrdU) studies.
- Analysis of cell-derived microvesicles.
Main Results:
- Murine hematopoietic stem cells are actively cycling, not quiescent.
- The purification of stem cells likely discarded these cycling populations.
- Even "quiescent" LT-HSCs in G0 rapidly enter the cell cycle.
- Cell-derived microvesicles alter marrow cell fate and phenotype.
Conclusions:
- The hematopoietic stem cell model requires revision to incorporate continuous cell cycling.
- Stem cell phenotype and potential are dynamic, influenced by cell cycle and microvesicles.
- Future research should focus on defining the stem cell population rather than purification.
- This work opens avenues for understanding "quantum stemomics".
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