British scientists have created the first known batch of "gold standard" stem cells which 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, are of unprecedented quality and could be offered to researchers before the end of next year for eventual use in clinical trials.
Previous embryonic stem cell (ESC) trials in humans have used lower-quality "research grade" cells, which 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 are also untainted by animal-derived products which have been used by other researchers to stimulate growth.
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 researchers from King's College London.

Prof Peter Braude, a leading member of the team, said: "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."
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.
A line of cells of a similar quality is being developed by Manchester University researchers and is expected to be donated to the stem cell bank next month.
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 the achievement, recorded in the Cytotherapy journal, marked ten years of painstaking research.
He said: "Cells that are ready for clinical use have really been the Holy Grail of everybody in terms of regenerative medicine.
"There is still a long way to go ... these are not ready for use now. They get handed over to the stem cell bank and they do exhaustive testing and a lot of lines are going to fail."
The cells could be handed over to university scientists or private companies by the end of next year, though there would likely be a significant period of preparation by researchers before clinical trials actually began.
Dr Glyn Stacey, director of the UKSCB, said: "They will be released - I wouldn't like to put a date on it, but some time next year.
"The moment we release them they are ready for use in a clinical trial."
It is widely believed that ESCs could one day be used to generate healthy tissue to replace damaged cells throughout the body, and potentially form the basis of new treatments for conditions like heart disease and Parkinson's.
ESCs are taken from frozen embryos the size of a pinhead, which are donated to researchers by IVF patients who have no further use for them and would otherwise have been discarded.