Illustration by Cell Imaging Core of the Center for Reproductive Sciences
Scientists at Children's Hospital Oakland Research Institute (CHORI) led by Vladimir Serikov, MD, PhD, and , PhD, reported in Stem Cells Translational Medicine that placental stem cells with important therapeutic properties could be harvested in large quantities from human term s.
Placenta is normally discarded after delivery, but it contains stem cells of both fetal origin and maternal origin that appear to be pluripotent -- i.e., they can differentiate into different types of human cells, such as lung, liver, or brain cells. Since these functional placental stem cells can be isolated from either fresh or frozen term human placentas, this implies that if each individual's placenta is stored at birth instead of thrown away, these cells can be harvested in the future if therapeutic need arises. This potential represents a major breakthrough in the stem cell field.
Hematopoietic stem cells from the placenta are "siblings" of the cord blood stem cells. Cord blood stem cells have been used for many thousands of successful bone marrow transplants. But these transplants are restricted to children, as the amount of cells harvested from cord blood is usually not sufficient for a successful transplant in adults. Adding placental stem cells to the cord blood stem cells could make successful adult bone marrow transplants possible.
This report demonstrates that placental stem cells have much broader therapeutic potential than bone-marrow transplants, because they are pluripotent and they can also generate growth factors that help in tissue repair. Animal tests have shown that placental stem cells integrate into different tissues when transplanted, but in contrast to embryonic pluripotent stem cells, they do not form tumor-like structures in mice.
Placental-derived stem cells are "adult" stem cells in contrast to "embryonic" stem cells and these stem cells can be harvested in large numbers without ethical concerns. These stem cells may thus be a more practical source for regenerative medicine, particularly since, if placentas are routinely saved instead of thrown away, each individual will be able to draw on their own placental stem cells if future therapeutic needs arise.
Placental stem cells are only 9 months old, with characteristics of young and vigorous cells, including young mitochondria. At present many research institute have brought placental stem cells to animal tests and clinical trials, and to test their efficacy in translational therapeutic applications.