6 September 2011
NZ science breakthrough: first virus-free pluripotent stem cells in cattle
International science publication PloS ONE, the world's largest scientific journal, has published a research discovery
by AgResearch scientists into cattle stem cells.
The science team at Ruakura, led by Dr Björn Oback, has produced the first virus-free pluripotent stem cell-like cells
in cattle, a species where similar attempts have failed for decades.
Dr Oback predicts that this discovery and the convergence of reproductive and stem cell technology will unlock a new
realm of practical possibilities for agriculture. "This breakthrough shows that by firmly focussing on farm animals,
with cattle as a model system, we can leverage New Zealand's distinct strengths and make important scientific
contributions to this field of research," said Dr Oback.
Induced pluripotent stem cells (iPSCs) are capable of turning into any cell type in the body, an ability referred to as
'pluripotency'. Unlike embryonic stem cells, which are also pluripotent, iPSCs do not require destruction of an early
embryo but can be derived from almost any cell in the body.
Dr Ben Huang, AgResearch Scientist and lead author of the study, attributes the success to a novel culture medium. "This
medium promotes pluripotency by inhibiting different cell signalling pathways. Using signal inhibition, we induced stem
cell markers in bovine skin cells. We then coaxed them into forming mature tissues after transplantation into mice",
explains Dr Huang. "Importantly, the culture conditions were completely chemically defined and free of potentially
pathogenic components, such as feeder cells or serum," he said.
Unlike iPSCs in other species, the bovine cells did not require viruses to carry pluripotency-inducing genes into cells.
For their virus-free approach, AgResearch scientists simply incubated skin cells in plasmid DNA encoding the
pluripotency factors and watched the cells reprogramme back into an embryonic stem cell-like state. This delivery route
is safer than viruses, which can trigger the immune system and cause tumours. Plasmids are also easy-to-use and cheap,
eliminating the need for specialised biohazard containment facilities.
New Zealand will ultimately benefit from this advance in stem cell technologies. Future agricultural applications
include the ability to generate animals whose sperm are made from iPSCs. In such animals could be used to effectively
capture and multiply elite genetics, taking genomic selection from the whole animal to the cellular level, accelerating
breeding and genetic gain.
The research was funded by the New Zealand Foundation for Research, Science and Technology (the Ministry of Science and
Innovation) and AgResearch.