Two million of these cells are produced each second

Jun 1, 2010 10:43 GMT  ·  By
This microscopy image shows that in a mouse embryo MiR451 (dark purple) is produced only in the liver, where red blood cells are being formed at this developmental stage
   This microscopy image shows that in a mouse embryo MiR451 (dark purple) is produced only in the liver, where red blood cells are being formed at this developmental stage

One of the fundamental truths about our bodies is that most cells need oxygen to survive. We inhale the chemical each breath we take, then take it to our lungs, where the precious molecules are then attached to hemoglobin, one of the most important proteins we have. Hemoglobin itself is housed on red blood cells, elements of the blood that are the main delivery networks through which oxygen reaches the cells. More than two million of these cells are produced each second, because they have a very short lifespan. Now, researchers believe they've identified the molecules that control the efficiency of this production process, AlphaGalileo reports.

Scientists say that, other than the massive amounts of red blood cells produced every second, even more are generated when the body experiences a shock, such as an injury that results in hemorrhage. In a new study, researchers in Monterotondo, Italy, at the European Molecular Biology Laboratory (EMBL), and Hinxton, UK, at the EMBL European Bioinformatics Institute (EMBL-EBI), have determined that two types of microRNA, called MiR144 and MiR451, control the final stages of the production process. Details of the work appear in the June 1 issue of the esteemed scientific Journal of Experimental Medicine.

The two small ribonucleic acid molecules act on red blood cells production by fine-tuning the collective action of a large number of genes that code for this process. “A lot of the effort of blood cell formation, or hematopoiesis, goes into just keeping enough red blood cells in circulation. We’ve identified two molecules that help to do so, and which are essential in challenging situations,” explains EMBL Monterotondo team leader Donal O’Carroll. The expert adds that the research team developed a lineage of genetically-engineering lab mice, which lacked either MiR144, or MiR451.

The team was surprised to learn that, even though red blood cell production was impaired in the rodents, their organisms made up for it. In addition to forming these oxygen-carrying cells in the bone marrow alone, the animals began producing them in the spleen. The large number of precursor cells compensated for the fact that only a small number of them matured into fully-fledged red blood cells (due to the lack of necessary RNA molecules). The mice therefore survived with only minor concussions.

“Under steady-state conditions, mice without MiR144 or MiR451 can just about produce enough red blood cells, but if you challenge them, by chemically inducing anemia, most of them don’t survive, because in those conditions you just can’t live with inefficient red blood cell formation,” O’Carroll concludes.