Stem cells from frozen human embryos

A team of South Korean researchers have managed to extract embryonic stem cell (ES cells) from frozen human embryos. The researchers, based at the Maria Infertility Hospital in Seoul, have obtained seven ES cell lines from 20 embryos left over from infertility treatment. The news follows the recent success of another South Korean team, based at the Seoul National University, who have managed to obtain ES cells from fresh cloned human embryos. Commenting on the new study, the National University team leader Hwang Woo-Suk said that the success rate of the Maria scientists was astounding, describing the research as 'work of magic hands'. The new study is published in the journal Human Reproduction.

The researchers, lead by Park Se-Pill, carried out their work on 20 human embryos obtained from local fertility clinics, which were scheduled to be destroyed after five years in storage. ES cells - the body's 'master cells' capable of growing into any type of tissue - are present in very early embryos. According to Park, the key to successfully extracting ES cells is isolating the clumps of cells that contain them without causing any damage. The researchers obtained these 'inner cell masses' (ICMs) using a new antibody technique, for which they have applied for patents in 108 countries. Using the new technology, they achieved a success rate of over 60 per cent, which is apparently much higher than any previously reported.

Many scientists hope that research using ES cells will lead to new treatments for a range of diseases, including Alzheimer's disease and diabetes. But such work is currently limited by the number of human ES cell lines available. 'By succeeding in deriving stem cells from frozen embryos, we will be able to raise the efficiency of experiments while minimising the use of human eggs', said Park.

Park plans to set up an ES cell bank, which he says could eventually be used to treat diseases the same way as existing bone marrow banks. However, the cell lines reported in the latest study were grown using mouse feeder cells, which means they would be unsuitable for use in human trials.

One alternative to a bank of different human ES cells for stem cell treatments is to derive genetically-identical ES cells for each patient, so-called 'therapeutic cloning'. The work reported last month by Hwang's team was hailed as a major step towards this possible new approach.