Stem cells found in amniotic fluid can be transformed into a more versatile state similar to embryonic stem cells, according to a study published today in the journal Molecular Therapy. Scientists from Imperial College London and the UCL Institute of Child Health succeeded in reprogramming amniotic fluid cells without having to introduce extra genes. The findings raise the possibility that stem cells derived from donated amniotic fluid could be stored in banks and used for therapies and in research, providing a viable alternative to the limited embryonic stem cells currently available.
Amniotic fluid surrounds and nourishes the fetus in the womb. It can be extracted through the mother's abdomen using a needle in a process called amniocentesis, which is sometimes used to test for genetic diseases. The fluid contains stem cells that come from the fetus. These cells have a more limited capacity to develop into different cell types than stem cells in the embryo.
The researchers used stem cells from amniotic fluid donated by mothers undergoing amniocentesis for other purposes during the first trimester of pregnancy. The cells were grown on a gelatinous protein mixture in the lab and reprogrammed into a more primitive state by adding a drug called valproic acid to the culture medium. An extensive set of tests found that these reprogrammed cells have characteristics very similar to embryonic stem cells, which are capable of developing into any cell type in the body - a property known as pluripotency.
Even after growing in culture for some time, the reprogrammed cells were able to develop into functioning cells of many different types, including liver, bone and nerve cells. They also maintained their pluripotency even after being frozen and rethawed.
The results suggest that stem cells derived from amniotic fluid could be used in treatments for a wide range of diseases. Donated cells could be stored in banks and used in treatments, as well as in disease research and drug screening. A previous study estimated that cells from 150 donors would provide a match for 38% of the population.
Alternatives to embryonic stem cells are keenly sought because of ethical concerns and limited availability of donor embryos. Previous research has shown that it is possible to make adult cells become pluripotent by introducing extra genes into the cells, often using viruses. However, the efficiency of the reprogramming is very low and there is a risk of problems such as tumours caused by disrupting the DNA. The new study is the first to induce pluripotency in human cells without using foreign genetic material. The pluripotent cells derived from amniotic fluid also showed some traits associated with embryonic stem cells that have not been found in induced pluripotent stem cells from other sources.
Amniocentesis is associated with a small risk of causing a miscarriage, estimated to be about one in 100.