Source: University of California - Los Angeles
Date: March 1, 2012
Summary:
UCLA stem-cell researchers have identified a certain type of cell and a signaling pathway in the placental niche that play a key role in stopping blood stem cells from differentiating into mature blood cells in the placenta. Preventing this premature differentiation is critical to ensuring a proper blood supply for an individual's lifetime.
The placental niche is considered a stem cell "safe zone," which supports the creation and expansion of blood stem cells without promoting their differentiation into mature cells. This allows for the establishment of a pool of precursor cells that will later provide blood cells for fetal and post-natal life, said the study's senior author, Dr. Hanna Mikkola, an associate professor of molecular cell and developmental biology at UCLA and a researcher at UCLA's Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research.
Mikkola and her team found that PDGF-B signaling in specialized cells in the placenta called trophoblasts — which facilitate embryo implantation and exchanges of nutrients between the mother and fetus — is vital to maintaining the unique micro-environment needed for the blood precursor cells. When PDGF-B signaling is halted, these blood precursors differentiate too early, creating red blood cells in the placenta, Mikkola said.
The study, done in mouse models, appears March 1 in the peer-reviewed journal Developmental Cell.
