Circadian rhythms influence hematopoietic stem cells.
OBJECTIVE
Hematopoiesis is tightly regulated in the bone marrow through the microenvironment, soluble factors from the circulation, and neural inputs from the autonomic nervous system. Most physiological processes are not uniform but rather vary according to the time of day. There is increasing evidence showing the impact of biological rhythms on the traffic of hematopoietic stem cells (HSCs) and their proliferation and differentiation capacities.


RESULTS
Recent evidence supports the role of the sympathetic nervous system in the regulation of HSC behavior, both directly and through supporting stromal cells. In addition, the sympathetic nervous system transduces circadian information from the central pacemaker in the brain, the suprachiasmatic nucleus, to the bone marrow microenvironment, directing circadian oscillations in hematopoiesis and HSC migration.


CONCLUSIONS
HSC traffic and hematopoiesis do not escape the circadian regulation that controls most physiological processes. Clinically, the timing of stem cell harvest or infusion may impact the yield or engraftment, respectively, and may result in better therapeutic outcomes.
Department of Medicine, USA bDepartment of Gene and Cell Medicine, USA.
Simón
S
Méndez-Ferrer
Andrew
A
Chow
Miriam
M
Merad
Paul S
PS
Frenette
D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D006410:Hematopoiesis / Q000502:physiology*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D013564:Sympathetic Nervous System / Q000502:physiology