The placenta does more than provide yet unborn babies with oxygen from the mother’s blood supply; they are also a rich source of stem cells. Vladamir Serikov from the Children’s Hospital Oakland Research Institute in Oakland, California first isolated and characterized “chorionic mesenchymal stem cells” from human placenta in 2009 (see Exp Biol Med 2009 234:813-23), and since that time, his work has been conformed by several other research labs (Cell Stem Cell 2009 5:385-95 & Dev Biol 2009 327:24-33). Now Serikov and his research team have used his hCMSCs to repair damaged lungs in laboratory animals.
In this present publication, the Serikov team grew placenta-derived hCMSCs in culture and discovered that these grew like gangbusters. After 100 doublings, the cells showed no signs of giving up and their chromosomes show no signs of shortening, which is a symptom of aging when cells are grown in culture. Stem cells, have the ability to properly maintain the ends of their chromosomes and not show these signs of aging. Serikov’s hCMSCs have this definitive stem cell ability.
Next, the Oakland-based team tried to get these hCMSCs to differentiate into various cell types using published protocols. The hCMScs formed fat cells, bone cells, blood vessel-like cells, and liver cells in culture. When treated with a molecule called nerve growth factor, hCMSCs even sprouted nerve cell-like extensions and expressed genes common found in neurons (the cells that make a propagate nerve impulses).
To determine if these cells had the capacity to heal damaged tissue, Serikov and co-workers treated human lungs that were donated by a deceased individual but were denied for transplantation with a bacterial toxin that tends to really screw up the lungs. One lobe of the lung was treated with toxin only but the other side was treated with the toxin and five million hCMSCs. The side that received only the toxin showed damage to the lining of the lungs that was reflected in poor gas exchange and high fluid uptake by the lung tissue, but the side that received the hCMSCs was able to properly pump out the liquid and maintain the structure of the lung. When this same assay was applied to cultured lung tissue from humans, it was clear that the hCMSCs helped repair the columns of lung cells through the modicum of growth factors that they secrete. Certainly, hCMSCs have the capacity to heal the lungs after they are ravaged by a deadly bacterial toxin.
Two other experiments underscored the therapeutic capacity of these cells. When hCMSCs were infused into mice after the animals have been hit with high doses of radiation, they took up residence in multiple tissues, including the intestine, lungs, brain, and liver. Therefore, hCMSCs can not help heal tissues by means of what they secrete (so-called paracrine mechanisms), but by incorporating into tissues and becoming an integral part of it. Finally, when hCMSCs were implanted into mice and examined one year later, none of the mice showed any signs of tumors. There were also no signs of pain, heart problems, distress, fever, or weight loss. Therefore, these cells seem to be well tolerated, and do not have a high capacity for tumor formation.
These preclinical studies should give way to studies in larger animals, and if those are successful, hopefully, the first human clinical trials with these amazing stem cells that come from an abundant source, the human afterbirth.
See Igor Nazarov et al., “Multipotential Stromal Stem Cells from Human Placenta Demonstrate High Therapeutic Potential,” Stem Cells Translational Medicine 2012 1:359-72.