By Kate Kelland
LONDON (Reuters) - British scientists have made the first human embryonic stem cells of a high enough grade to use in patients and deposited them in a public stem cell bank for development in human trials by drug companies and researchers by 2014.
A team from King's College London said on Monday they were submitting two clinical-grade stem cell lines to the UK Stem Cell Bank (UKSBC), which will test and validate them before offering them to researchers.
This could speed the path towards new stem-cell treatments for conditions like blindness, severe injury or heart disease.
"This first batch of cells is the culmination of nearly 10 years of research. This is a significant milestone," said Peter Braude, who led the King's team.
The cells are the first to be grown completely free from animal-derived products, known as "xeno-free," and developed specifically to be of clinical grade and for public use.
The hope is that the cells will be grown and processed by the bank to feed cell stocks for human trials and, beyond that, patient treatments.
The cells have the potential to become the "gold standard" lines for developing new stem cell based therapies for use in regenerative medicine trials in patients, Braude told reporters at a briefing.
It is likely to be many years before treatments are fully developed and licensed, but the cells could be used in human trials of potential therapies by 2014, the team said.
Stem cells are the body's master cells, the source for all other cells. Scientists say they could transform medicine, providing treatments for blindness, spinal cord and other severe injuries, as well as generating cells for damaged organs.
Human embryonic stem (hES) cells can be grown in the laboratory indefinitely while retaining their capacity to develop into specialized cell types, such as nerve or heart muscle cells, which can then be used in clinical trials.
The UK Stem Cell bank already has more than 90 research grade stem cell lines for use in laboratory studies, but as yet has no clinical grade xeno-free lines for use in human trials.
"In the future, patients hoping for the benefit of regenerative medicine for serious medical conditions caused by illness, injury and ageing can expect improved progress on cures or amelioration from hES cell-based therapy," said Dusko Ilic, a senior lecturer in stem cell science at King's.
A few companies, such as Pfizer and Advanced Cell Technology, are already conducting or are about to start human trials using hES cells -- which are harvested from embryos -- to test their potential for repairing spinal cord injuries and eye disorders like macular degeneration.
But the hES cell lines for these early trials were reclassified from "research grade" to "clinical grade" for specific short-term clinical studies in selected disease areas.
Braude said this is not considered appropriate for the future of cell therapy because of the expense of extra testing and reclassification, and the potential risks.
"While it might be reasonable to incur additional risks for these early pioneering studies, it is not reasonable to accept these risks for the long-term future," he said. "Therefore the highest standard of xeno-free lines are urgently needed."
Braude's team's cells were grown from frozen embryos donated by patients who had had in-vitro fertilization (IVF) treatment and no longer wanted to use their remaining stored embryos. The embryos would otherwise have been discarded, Braude said.
Glyn Stacey, head of the UKSCB, said these first clinical grade lines would be an "important resource" and an initial step towards the bank's aim to make available a panel of tested clinical grade lines within the next three years.
"The process of testing will be rigorous and not all cells lines received will make the grade," he said.
(Editing by David Cowell)