London: Scientists have developed the first known batch of "gold standard" stem cells which they say could one day lead to a new wave of treatments for degenerative diseases.

The stem cells, taken from human embryos and grown in the lab by researchers at the King's College London, are claimed to be of unprecedented quality which scientists could use in clinical trials before the end of next year.

According to the researchers, previous embryonic stem cell (ESC) trials in humans have used lower-quality "research grade" cells that are manipulated and reclassified into "clinical grade".

But, the new ESCs, described as the "Holy Grail for regenerative medicine", are of clinical quality from the moment they are donated by patients and do not require a costly and risky conversion, they said.

They are also untainted by animal-derived products which have been used by other researchers to stimulate growth, a daily reported.

Two lines of stem cells, which can be converted into virtually any type of tissue in the body, have been donated to the UK Stem Cell Bank (UKSCB) by the researchers.

"The key here is that these are clinical grade lines, they have been set up from the beginning as lines that do not contain animal products and have not got animal products coming into contact with them," said Prof Peter Braude, a leading member of the team.

While ESCs of similar quality could potentially have been cultured in secret by private researchers such as drug companies, these are the first of their kind to be developed for public health benefit.

At the UKSCB the cell lines will undergo rigorous testing to ensure they are safe and of a sufficient calibre for use in human trials, but it is hoped they will be a "seedstock" for future experiments.

Prof Braude said their achievement, which is detailed in the Cytotherapy journal, marked ten years of painstaking research.