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In vitro expansion of hematopoietic stem cells
1Ralph H. Johnson Department of Veterans Affairs Medical Center, Department of Medicine, Medical University of South Carolina, Charleston, USA.
Abstract:
We have investigated the effects of interleukin 3 (IL-3) and IL-1 on in vitro expansion of murine hematopoietic progenitors and stem cells using a highly purified progenitor population. Lineage negative, Ly-6A/E+, c-kit+ bone marrow cells from male mice were cultured in suspension in the presence of stem cell factor, IL-6, IL-11 and erythropoietin with or without IL-3 or IL-1. An exponential increase in total nucleated cell counts and about a 10-fold enhancement of nucleated cells by IL-3 were observed during the initial 10 days. Addition of IL-3 hastened the development but significantly suppressed the peak production of colony-forming cells. Addition of IL-1 also significantly suppressed the numbers of progenitors. We then tested the reconstituting ability of the cultured cells by transplanting cells together with "compromised" marrow cells into lethally irradiated mice. The cells expanded from enriched cells in the absence of IL-3 or IL-1 revealed engraftment at two, six and 10 months, while addition of IL-3 or IL-1 to the cultures significantly reduced the reconstituting ability. IL-3 and IL-1 may have negative modulatory effects on the self-renewal of stem cells.
Insights
Interleukin-3 (IL-3) and Interleukin-1 (IL-1) negatively impact hematopoietic stem cell self-renewal. These cytokines suppressed progenitor numbers and reduced the reconstituting ability of expanded stem cells in vivo.
Area of Science:
- Hematology
- Immunology
- Stem Cell Biology
Background:
- Hematopoietic stem cells (HSCs) are crucial for lifelong blood cell production.
- Interleukins (ILs) are key regulators of immune responses and hematopoiesis.
- Understanding cytokine effects on HSCs is vital for regenerative medicine.
Purpose of the Study:
- To investigate the in vitro effects of IL-3 and IL-1 on murine hematopoietic progenitor and stem cell expansion.
- To assess the impact of IL-3 and IL-1 on the self-renewal and reconstituting ability of HSCs.
Main Methods:
- Purified murine bone marrow progenitor cells (Lineage negative, Ly-6A/E+, c-kit+) were cultured with stem cell factor, IL-6, IL-11, and erythropoietin.
- Cultures were supplemented with either IL-3 or IL-1 to evaluate their effects.
- The reconstituting ability of cultured cells was assessed by transplantation into lethally irradiated mice.
Main Results:
- IL-3 initially enhanced nucleated cell counts but suppressed peak colony-forming cell production.
- Both IL-3 and IL-1 significantly reduced progenitor cell numbers in vitro.
- HSCs expanded without IL-3 or IL-1 demonstrated sustained engraftment, while IL-3/IL-1 addition impaired reconstituting ability.
Conclusions:
- IL-3 and IL-1 exhibit negative modulatory effects on HSC self-renewal and expansion.
- The absence of IL-3 and IL-1 during in vitro culture promotes superior HSC reconstituting potential.
- These findings suggest a critical role for specific cytokine environments in maintaining HSC stemness.