Research on Placental Stem Cells
Research on Placental Stem Cells
In a press release published on Business Wire on September 26, the biotech company StemCell Pharma described the use of the placenta as a source for stem cells but warned of possible dangers in using the entire placenta, including the chorion. StemCell Pharma is a Las-Vegas based company with a proprietary placenta stem cell implant technique. (The company profile can be found on Stem News. ) The release summarizes the benefits and risks of using the entire placenta:
The placenta has three parts: the maternal placenta, the amniotic sac, and the chorion, which is the membrane that surrounds the amniotic sac and fetus. Stem cells obtained from the maternal placenta and the amniotic sac have shown great promise in differentiation. However, research has not been conducted specifically on stem cells from the chorion. The chorion’s function is to provide hormones to the fetus and to suppress immune system rejection responses by the mother. One hormone, cortisol, can produce cancer in experimental animals. Therefore, researchers should extract the chorion rather than using cells obtained from the “whole” placenta.
The release appears in part to be a response to a study by University of Pittsburgh researchers published in the online version of the journal Stem Cells in August (abstract). The University of Pittsburgh’s newspaper the Pitt Chronicle summarized the study on September 26 (the article is the same as a prior news release from UPMC on August 5, which was reported by other media sources at the time):
Cells from the amnion, or outer membrane of the amniotic sac, can express two key genes for pluripotency (Oct-4 and nanog). However, such amniotic epithelial cells cannot grow indefinitely, possibly because they do not express the enzyme telomerase, which is responsible for DNA replication and cell division. Telomerase is associated with many cancers. Despite being unable to grow indefinitely, the amniotic cells had grown their own “feeder layer” in the laboratory cultures, and the cells were not contaminated by mouse cells otherwise needed for embryonic stem cell growth. The researchers injected the amnion-derived cells into several locations in mice whose immune systems were deficient. There was no evidence of tumors seven months later. The researchers believe the amniotic cells could differentiate into liver cells, heart cells, some nervous system cells, and pancreatic cells.
On September 27, the British group Corethics (Comment on Reproductive Ethics; according to the website, “CORE is a public interest group focusing on ethical dilemmas surrounding human reproduction,” and “Absolute respect for the human embryo is a principal tenet”) issued a brief report on research by scientists at Celgene Cellular Therapeutics Division. The scientists have been doing research on migrating placental stem cells to the vascular spaces where cells can be more easily extracted and isolated.
One of the key advantages of the placenta over embryos as a source for stem cells is the quantity; there are over 4 million placentas otherwise discarded as medical waste annually in the U.S. alone. Corethics also reports that the cells are likelier to be healthy cells than those obtained from embryos, are thought to have a low risk of infection, and have a graft tolerance inducing ability.