(Press-News.org) A research team of Inserm, CNRS and MDC lead by Michael Sieweke of the Centre d'Immunologie de Marseille Luminy (CNRS, INSERM, Aix Marseille Université) and Max Delbrück Centre for Molecular Medicine, Berlin-Buch, today revealed an unexpected role for hematopoietic stem cells: they do not merely ensure the continuous renewal of our blood cells; in emergencies they are capable of producing white blood cells "on demand" that help the body deal with inflammation or infection. This property could be used to protect against infections in patients undergoing bone marrow transplants, while their immune system reconstitutes itself. The details of the research is published in Nature on april 10th 2013.
Cells in our blood feed, clean and defend our tissues, but their lifespan is limited. The life expectancy of a red blood cell rarely exceeds three months, our platelets die after ten days and the vast majority of our white blood cells survive only a few days.
The body must produce replacement cells in a timely manner. This is the role of hematopoietic stem cells, more commonly called blood stem cells. Nestled in the core of the bone marrow (the soft tissue in the center of long bones such as the chest, spine, pelvis and shoulder), they dump billions of new cells into the bloodstream every day. To accomplish this strategic mission, they must not only multiply but also differentiate, i.e. to produce specialized white blood cells, red blood cells or platelets.
For many years, researchers have been interested in how this process of specialization is triggered in stem cells. Michael Sieweke and his team previously discovered that the latter do not engage randomly in a particular differentiation pathway but "decide" their fate under the influence of internal factors and signals from the environment.
An important issue remains: how do stem cells manage to respond appropriately to emergencies? For example, are they able to meet the demand by producing white blood cells like macrophages to eat microbes during infection?
Until now, the answer was clear: the stem cells could not decode such messages and were content to differentiate randomly. Michael Sieweke's team has demonstrated that, far from being insensitive to these signals, stem cell perceive them and in return manufacture the cells that are most appropriate for the danger that is faced.
"We have discovered that a biological molecule produced in large quantities by the body during infection or inflammation directly shows stem cells the path to take," said Dr. Sandrine Sarrazin, Inserm researcher, co-author of the publication. "As a result of this molecule, called M-CSF (Macrophage Colony-Stimulating Factor), the switch of the myeloid lineage (the PU.1 gene) is activated and the stem cells quickly produce the cells that are best suited to the situation such as macrophages."
Now that we have identified this signal, it may be possible in the future to accelerate the production of these cells in patients facing the risk of acute infection," said Dr. Michael Sieweke, CNRS Research Director. "This is the case for 50,000 patients worldwide each year* who are totally defenseless against infections just after bone marrow transplantation. Thanks to M-CSF, it may be possible to stimulate the production of useful cells while avoiding to produce those that can inadvertently attack the body of these patients. They could therefore protect against infections while their immune system is being reconstituted".
About the discovery
This seemingly simple discovery is quite original, both in its approach and by the technology it required. To reach their conclusions the team had to measure the change of state in each cell. This was a double challenge: the stem cells are not only very rare (there is only one stem cell per 10,000 cells in the bone marrow of a mouse), but they are also completely indistinguishable from their descendants.
"To differentiate the protagonists we used a fluorescent marker to indicate the status (on or off) of the myeloid cell switch: the protein PU.1. First in the animal, then by filming the accelerated cell differenciation under a microscope, we showed that stem cells "light-up" almost immediately in response to M-CSF," said Noushine Mossadegh-Keller, CNRS assistant engineer, co-author of this publication. "To be absolutely sure, we recovered the cells one by one and confirmed that the myeloid genes were activated in all the cells that had turned green: once they perceived the warning message, they changed identity."
### END
The surprising ability of blood stem cells to respond to emergencies
2013-04-11
ELSE PRESS RELEASES FROM THIS DATE:
First objective measure of pain discovered in brain scan patterns by CU-Boulder study
2013-04-11
For the first time, scientists have been able to predict how much pain people are feeling by looking at images of their brains, according to a new study led by the University of Colorado Boulder.
The findings, published today in the New England Journal of Medicine, may lead to the development of reliable methods doctors can use to objectively quantify a patient's pain. Currently, pain intensity can only be measured based on a patient's own description, which often includes rating the pain on a scale of one to 10. Objective measures of pain could confirm these pain reports ...
CPAP improves work productivity for sleep apnea patients
2013-04-11
The study will be presented today (11 April 2013) at the Sleep and Breathing Conference in Berlin, organised by the European Respiratory Society and the European Sleep Research Society.
Previous research has demonstrated that people with sleep apnoea are less productive at work, usually due to excessive daytime sleepiness. This study aimed to assess whether continuous positive airway pressure (CPAP) improved productivity at work.
The researchers used the Endicott Work Productivity Scale, a questionnaire designed to assess productivity at work, and the Epworth Sleepiness ...
Great white sharks
2013-04-11
MIAMI –April 9, 2013 – Many terrestrial animals are frequently observed scavenging on other animals– whether it is a hyena stealing a lion kill in the Serengeti or a buzzard swooping down on a dead animal. However, documenting this sort of activity in the oceans is especially difficult, and often overlooked in marine food web studies.
In a new study published in PLOS ONE titled, "White sharks (Carcharodon carcharias) scavenging on whales and its potential role in further shaping the ecology of an apex predator," Captain Chris Fallows from Apex Expeditions collaborated ...
Extreme algae blooms: The new normal?
2013-04-11
A 2011 record-breaking algae bloom in Lake Erie was triggered by long-term agricultural practices coupled with extreme precipitation, followed by weak lake circulation and warm temperatures, scientists have discovered.
The researchers also predict that, unless agricultural policies change, the lake will continue to experience extreme blooms.
"The factors that led to this explosion of algal blooms are all related to humans and our interaction with the environment," says Bruce Hamilton, program director at the National Science Foundation (NSF), which funded the research ...
Single best practice to prevent DVT reduces hospital costs by more than $1.5 million annually
2013-04-11
Chicago (April 10, 2013)—A major challenge facing today's health care community is to find ways to lower costs without compromising clinical quality. Taking that challenge to task, researchers at Medstar Health and Georgetown University School of Medicine, Washington DC, report success in using a concept called "value-based analysis," which simultaneously measures quality and cost and addresses inefficiencies in care. The researchers applied a value-based analysis approach to implementing a single best practice for preventing deep vein thrombosis (DVT) in surgical patients ...
Metabolic fingerprinting: Using proteomics to identify proteins in gymnosperm pollination drops
2013-04-11
Proteins are vital parts of living organisms, performing a variety of essential functions such as DNA replication, catabolizing reactions, and responding to stimuli. The complete set of proteins expressed in an organism at a given time, under defined conditions, is known as the proteome. While the genome of an organism remains relatively stable, the proteome is remarkably dynamic, varying from cell to cell and even within a single cell and changing rapidly in response to developmental and environmental cues.
Proteomics is a powerful technique for examining the structure ...
Subconscious mental categories help brain sort through everyday experiences
2013-04-11
Your brain knows it's time to cook when the stove is on, and the food and pots are out. When you rush away to calm a crying child, though, cooking is over and it's time to be a parent. Your brain processes and responds to these occurrences as distinct, unrelated events.
But it remains unclear exactly how the brain breaks such experiences into "events," or the related groups that help us mentally organize the day's many situations. A dominant concept of event-perception known as prediction error says that our brain draws a line between the end of one event and the start ...
Scientists decode genome of painted turtle, revealing clues to extraordinary adaptations
2013-04-11
Humans could learn a thing or two from turtles, and scientists who have just sequenced the first turtle genome uncovered clues about how people can benefit from the shelled creatures' remarkable longevity and ability to survive for months without breathing.
Understanding the natural mechanisms turtles use to protect their heart and brain from oxygen deprivation may one day improve treatments for heart attack and stroke, the researchers said.
UCLA conservation biologist and lead author Brad Shaffer collaborated with the Genome Institute at Washington University in ...
U-M researchers find new way to clear cholesterol from the blood
2013-04-11
ANN ARBOR—Researchers at the University of Michigan have identified a new potential therapeutic target for lowering cholesterol that could be an alternative or complementary therapy to statins.
Scientists in the lab of David Ginsburg at the Life Sciences Institute inhibited the action of a gene responsible for transporting a protein that interferes with the ability of the liver to remove cholesterol from the blood in mice. Trapping the destructive protein where it couldn't harm receptors responsible for removing cholesterol preserved the liver cells' capacity to clear ...
In sales, confidence and charisma may not seal the deal
2013-04-11
Think of a stereotypical salesperson and you're likely to conjure up someone who's extraverted, gregarious, and assertive. But a new study reveals that "ambiverts," people who are neither introverted nor extraverted but who fall somewhere in between, tend to be the most effective salespeople.
The study is published in Psychological Science, a journal of the Association for Psychological Science.
Researcher Adam Grant of The Wharton School of the University of Pennsylvania was driven to explore the relationship between sales and personality traits after realizing there ...