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Circulating hematopoietic stem cells do not efficiently home to bone marrow during homeostasis
Shannon McKinney-Freeman1, Margaret A Goodell
1Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, Texas 77030, USA.
Experimental Hematology
|September 4, 2004
Summary
Hematopoietic stem cells (HSCs) do not return to bone marrow after circulating. Instead, these stem cells establish function in peripheral tissues like skeletal muscle.
Area of Science:
- Hematology
- Stem Cell Biology
- Immunology
Background:
- Hematopoietic stem cells (HSCs) reside in bone marrow but are also found in circulation.
- Previously, circulating HSCs were thought to freely traffic between bone marrow and blood.
- Evidence suggests circulating HSCs may have impaired repopulating ability or low prevalence.
Purpose of the Study:
- To investigate the dynamics of circulating hematopoietic stem cells (HSCs).
- To determine if circulating HSCs stably re-engraft bone marrow.
- To analyze HSC stem cell compartments in parabiosed mice.
Main Methods:
- Parabiosis model in CD45 congenic mice.
- Analysis of bone marrow and skeletal muscle HSC compartments.
- Functional assessment via bone marrow transplantation.
- Phenotypic analysis using flow cytometry.
Main Results:
- Stem cells trafficking from bone marrow do not stably return to re-engraft.
- Long-lived lymphoid precursors can stably re-engraft bone marrow.
- Circulating HSCs colonize skeletal muscle and account for HSC activity there.
Conclusions:
- Circulating hematopoietic stem cells (HSCs) are not in flux with bone marrow HSCs.
- HSCs can persist and maintain activity in peripheral tissues.
- This challenges the notion of constant HSC trafficking and bone marrow homing.