Study Reveals How Blood Stem Cells Differentiate
A new study conducted by scientists at University of California, Los Angeles (UCLA) finds a new stem cell niche along with a signaling tract, both having an important role in providing a good blood supply during life, whilst preventing any premature differentiation. The study has been published in the journal Developmental Cell. This newfound stem cell niche is responsible for the production and multiplication of stem cells without them differentiating into mature blood cells. This allows the development of a blood cell precursor pool, thus providing the necessary blood cells later in life, whenever needed.
Associate professor Dr. Hanna Mikkola reports that her team of researchers have found a link between trophoblasts and premature differentiation of blood stem cells. Platelet-derived growth factor subunit B (PDGFB) favors the exchange of nutrients and oxygen between the mother and fetus, thus being a vital factor in limiting the premature differentiation of blood precursors. This differentiation could lead to the appearance of red blood cells in the placenta. Researchers used laboratory rats for their studies.
Scientists previously discovered that the placenta is the place where numerous blood stem cells reside in an undifferentiated state until needed. Dr. Mikolla says that her team has discovered that the inhibition of the PDGFB causes the differentiation of the stem cells into normal red blood cells, thus providing the information that trophoblasts are a very important factor in this particular process. The inhibition of the PDFGB signals allows the production of Erythropoietin (EPO), which is in direct control of the differentiation of red blood cells process.
In order to verify the connection between every factor that was involved (cells and signaling paths), Dr. Mikolla and her team used laboratory rats with a discontinued placenta.
“The idea was, if we mess up the home where the blood stem cells live, how do these cells respond to the altered environment”, said Akanksha Chhabra, post-doctoral fellow of Dr. Mikolla and first author of the current paper. “We found that it was important to suppress EPO where blood stem cell expansion is desired and to restrict its expression to areas where red blood cell differentiation should occur”.
Dr. Mikolla suggests that the growth and differentiation of the blood stem cells into the placenta could be hazardous for the stem cell niche. She adds that progress has been made in the past years regarding the presence of niche cells in adult bone marrow, but only now have they discovered the importance of these niches in fetal growth.
“All hematopoietic niches in the embryo are unique in their own way, the stem cells are made in one location, expand in another and differentiate somewhere else”, says Dr. Mikolla.
The study shows a new discovery in the development of blood stem cells whilst offering new findings that could lead to further development of artificial hepatopoietic niches that could help researchers understand the defects that originate from the placenta.
Researchers received funds from the National Institutes of Health, the California Institute of Regenerative Medicine and UCLA.