After ten years of rigorous research, scientists at King's College London announced that they have submitted the first “xeno-free” human stem cells to the UK Stem Cell Bank.

Typically, laboratory stem cell growth uses a process called cell culturing in which the scientist coats the inner surface of embryonic cells with mouse embryonic skin cells. These animal cells serve as a surface platform and source of nutrients for the human cells. While this is effective for culturing cells, it is also a hazard to the cultured cells because there is a risk that the mouse cells can transmit viruses and other macromolecules to the human cells.

King's College has addressed this potential corruption of human cells by creating cell lines free of animal-derived products. Xeno-free cells are grown from frozen embryos donated by patients who have undergone in-vitro fertilization treatment; they are embryos that would have otherwise been discarded.

A number of phase one studies have already explored the clinical use of human embryonic stem cells, such as the treatment of spinal cord injury and macular degeneration, but the stem cells used in these trials were reclassified from “research grade” to “clinical grade” to advance research. This reclassification of cells has its flaws, however; not only is it expensive because of the testing required to reclassify cells, it is also risky due to the use of unqualified reagents, unqualified feeders, and undocumented environmental conditions. Thus, there is an urgent need for xeno-free cell lines to reduce cell therapy risks and push research foward in an expedient, cost-effective, and safe manner.

Because the xeno-free cells created by King's College are untainted by animal-derived products, they qualify as clinical grade quality cells and do not need to undergo the reclassification process.

Once these xeno-free cells pass quality assurance tests, they will be released by the UK Stem Cell Bank for use in clinical trials, public research and patient treatment. 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.”

‘I’m pleased that we have finally been able to supply the UK Stem Cell Bank with well-characterised hES cell lines for public use, and can therefore contribute to the ongoing consolidation of the UK as a leading international player in the stem cell field. 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 Dr. Dusko Ilic, senior lecturer in stem cell science at King’s College.