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Stem cells emerge at night

Stem cells undergo circadian cycles in humans, emerging from the bone marrow into the bloodstream at higher concentrations at night than in the day, according to a report in __Cell Stem Cell__ linkurl:this week.;http://www.cellstemcell.com/ The study suggests that a simple change in hospital procedures could significantly increase stem cell yield for therapy. "We can take advantage of [the findings] if we coordinate our clinical practices" to harvest stem cells for cancer patients late in the

By | October 8, 2008

Stem cells undergo circadian cycles in humans, emerging from the bone marrow into the bloodstream at higher concentrations at night than in the day, according to a report in __Cell Stem Cell__ linkurl:this week.;http://www.cellstemcell.com/ The study suggests that a simple change in hospital procedures could significantly increase stem cell yield for therapy. "We can take advantage of [the findings] if we coordinate our clinical practices" to harvest stem cells for cancer patients late in the day, said author Paul Frenette, a clinical researcher at Mount Sinai School of Medicine. The work is an update on a paper published linkurl:online in February;http://www.nature.com/nature/journal/v452/n7186/abs/nature06685.html by the same group in __Nature.__ In that study, Frenette and his colleagues showed that haematopoietic stem cells (HSCs) leave their niche in mouse bone marrow and travel through the blood during the day -- the mouse's time of rest. A cytokine called CXCL12 expressed by stromal cells in the bone marrow niche signals their movement; when CXCL12 levels go down, HSCs escape into the blood. When the levels increase, the cells return. HSCs are commonly used to replenish a patient's stem cells which are depleted during cancer thereapy. To determine whether these findings might be meaningful in clinical application, Frenette's group followed up with the current study, in which they examined stem cell cycles in humans. The researchers compared two time-points for HSC harvesting, one at 8am and one at 8pm in normal subjects, and saw a significant increase in HSC levels in the evening harvest. In practice, patients being treated with autologous HSCs over the course of cancer therapy are first treated with a drug, G-CSF, that forces the stem cells into the blood; the cells are then harvested with plasmapharesis. Frenette's group wanted to know "whether these physiological cycles are maintained? when you force the mobilization with drugs," he told __The Scientist.__ So the researchers compared the number of stem cells they were able to extract from cancer patients who underwent the procedure before 12:30 pm, to those that underwent the procedure before 3:30 pm. Even such a short time period made a difference -- they observed a significant increase in harvest at the later time point. Current practice in the clinic is to harvest stem cells in the morning, said Frenette, but moving the procedure to afternoon or evening could mean fewer plasmapheresis sessions for patients. It is unclear why the stem cells leave their niche during a patient's time of rest; Frenette speculates that "there might be some function in repair and regeneration," but added that those associations are hard to prove.
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Avatar of: null null

null null

Posts: 97

October 10, 2008

"it is unclear why the stem cells leave their niche during a patient's time of rest"\n\n\nSC are more easily displaced during the organism's rest time simply because their genome is off-duty then, part of its duty is to be on-call at the specific site where it is:\n\n\nLife's Chirality And Circadian Rhythm,\nEvidence Of Updated Darwinian Evolution \n\n\nA. Updated life's concepts:\n\n http://www.the-scientist.com/community/posts/list/20/122.page#423\n\n- Earth life consists of three strata: genes are primal organisms, genomes are evolved 2nd \n stratum organisms, and cellular organisms are evolved 3rd stratum.\n\n- Life's evolution started at genesis.\n\n- Life's evolution is not random. It is biased, driven by culture.\n\n\nB. Earliest evidences of updated Darwinian evolution:\n\n- Life's chirality \n http://www.the-scientist.com/community/posts/list/122.page#387\n http://www.physforum.com/index.php?showtopic=14988&st=180&#entry327715\n \n- Circadian rhythm\n\n http://forum.physorg.com/index.php?showtopic=14988&st=135&#entry301299\n\n\nSuggesting,\n\nDov Henis\nhttp://blog.360.yahoo.com/blog-P81pQcU1dLBbHgtjQjxG_Q--?cq=1
Avatar of: DAVID EVE

DAVID EVE

Posts: 1

October 10, 2008

Maybe I'm misunderstanding this post, but doesn't it show the opposite? if you can get more cells at 8pm and 3.30pm compared with 8am and 12.30 pm respectively, doesn't this mean more cells emerge during the day, particularly since they recommend extracting cells during the afternoon rather than the morning? Nevertheless a circadian rhythm is certainly of great interest, even if it does seem the wrong way round to me.
Avatar of: Edyta Zielinska

Edyta Zielinska

Posts: 6

October 10, 2008

Thank you for your question, David Eve. The results of this group?s earlier research in mice showed that more HSCs emerge during the day ? a time of rest for mice. They followed this study up by looking at two time points in healthy humans, one in the morning and one in the evening, and found more stem cells in evening harvest ? closer to a human?s time of rest. We can?t tell, from this study, exactly at what point the HSCs begin to shift to the blood and when they shift back to the bone marrow. But we can say that the levels are higher later in the day and in the evening.
Avatar of: Ken Dev

Ken Dev

Posts: 7

October 11, 2008

There has been a lot of research on the circidian rhythm and cancer treatment-- at least for some tumors. It has been found, e.g., that very early morning treatment is more effective with the same chemo regimen with far less toxicity than given at the standard time. However, don't expect the oncology nurses to be around to treat patients at unreasonable hours, kind though they are! \n\nThe question is: Has this any correlation with more production of stem cells at night? I'd be interested to hear since I am professionally interested in cancer therapeutics. \n\nReaders interested in circidian rhythm and tumors should look up the following papers:\n \n\nCircadian rhythm-modulated chemotherapy with high dose 5-fluorouracil against gastrointestinal cancers: evaluation and case report. Nagoya J Med Sci,Vol.62, 29-38 (1999)\n \nFu L, Lee CC. The Circadian Clock: Pacemaker and Tumour Suppressor. Nature, Reviews 2003; 3: 350-61.\n
Avatar of: Robert Pytlik

Robert Pytlik

Posts: 7

October 11, 2008

I think null nullĀ“s comment not only oversimplifies the issue but does not bring any evidence for his (her?) statement. The referrences do not address the topic but the personal views and beliefs of the blogger. I suppose this kind of argument would be perhaps appropriate in a religious debate, but not on a scientific blog.

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