Circadian Rhythm and blood formation

Haematopoietic stem cells (HSCs) circulate in the blood, where they can home to sites throughout the body. The release of these cells into the blood stream has now been found to be regulated by circadian rhythms. In mice, Haematopoietic stem cells undergo pronounced fluctuations corresponding to circadian oscillations induced by continuous light or by a 12-hour time-shift or’jet lag’. Timing of the expression of the chemokine CXCL12 in the stem cell niche was also in step with the oscillations in response to adrenergic signals delivered locally by nerves in the bone marrow. The rhythmic release of stem cells into the blood during the animal’s resting period suggests a possible role in regeneration.
Scadden 2008 Stem cells traffic in time Nature vol 452. pp 416-17
Mendez-Ferrers et al 2008 Haemopoietic stem cell relese is regulated by circadian oscillations Nature vol 452 pp 442-447

Martin Eastwood
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