The first known batch of "gold standard" stem cells taken from human embryos have been created by scientists. This creation could one day pave way for new wave of treatments for degenerative diseases.
The stem cells 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".
However, 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.
"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," the Telegraph quoted Peter Braude, a leading member of the team as saying.
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.
"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," he added.
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.
The study has been published in the Cytotherapy journal.