Amniotic fluid could provide alternative to embryonic stem cells

Stem cells taken from amniotic fluid can be reprogrammed into a more versatile state similar to embryonic stem cells (ES cells) without the introduction of extra genes, UK scientists have found. The discovery offers hope that these cells could be banked for therapeutic use, research and drug screening.

A team of researchers, led by Dr Pascale Guillot from the Department of Surgery and Cancer at Imperial College London and Dr Paolo de Coppi from the UCL Institute of Child Health, extracted stem cells from amniotic fluid donated by women who had undergone amniocentesis tests during early pregnancy.

The stem cells were then grown in the lab on a gelatinous protein mixture and a chemical called valproic acid was added to the culture medium. The acid transformed the cells into a more flexible, primitive state by altering the configuration of their DNA, without changing the cell's genetic code itself.

The stem cells were successfully transformed into a pluripotent state, meaning that, like ES cells, they had the capacity to develop into any cell type in the body. Importantly, this was achieved without adding any foreign genetic material.

By examining the reprogrammed cells, the scientists found that they had very similar properties to ES cells. They could give rise to many different types of functioning cells, including bone, liver, nerve and fat cells, and they maintained their pluripotency after being frozen and re-thawed.

Dr Guillot explained: 'Amniotic fluid stem cells are intermediate between [ES] cells and adult stem cells. They have some potential to develop into different cell types but they are not pluripotent. We've shown that they can revert to being pluripotent just by adding a chemical reagent'.

He also expressed an interest in exploring the use of these cells in 'genetic diseases diagnosed early in life or other diseases such as cerebral palsy'.

It is hoped that the cells could provide an alternative to ES cells, which are controversial and are in limited supply. Previous work has shown that adult cells, such as skin cells, can be reprogrammed to a pluripotent state, creating iPS cells. However the reprogramming efficiency is relatively low and often involves the use of viruses to introduce extra genes into the cells, which carries potential health risks.

Dr de Coppi said: 'This study confirms that amniotic fluid is a good source of stem cells. The advantages of generating pluripotent cells without any genetic manipulation make them more likely to be used for therapy'.