Dairy CRC develops new stem cell techniques

Scientists at the Dairy Cooperative Research Centre (CRC) have discovered new methods to isolate and maintain large numbers of bovine embryonic stem cells.

Working with early-stage (day 8) bovine embryos, Dr Paul Verma and Dr Ivan Vassiliev have developed new techniques allowing scientists to investigate a range of stem cell applications in the cow.

"Not only have we created one stem cell line, we've efficiently started creating numerous stem cell lines. We can produce them routinely now," said Dr Paul Verma, who is based at the Monash Institute of Medical Research.

Verma presented the team's findings at the Dairy Science 2006 conference in Mount Gambier this week. "No one has ever produced stem cell lines in a domestic species that they can maintain for a long period of time and that retain the property of stem cells," he said, although he said that stem cell lines for humans, mice and some primates have been characterised in some detail.

Rather than isolating stem cells from the inner cell mass of a pre-implantation embryo as is common practice at the moment, the scientists have isolated stem cells from intact embryos. They have also developed methods to mechanically assist the embryos attach to a feeder layer of cells which supports the stem cell populations in vitro.

Using current methods, scientists usually obtain a 5 to 10 per cent isolation rate of stem cells from the inner cell mass, said Verma. Of the stem cells isolated by this method, only 30 per cent expressed pluripotent stem cell markers, the other 70 per cent differentiated soon after. However, with their new technique, Verma found that between 60 and 70 per cent of embryos gave rise to stem cell lines and of those, almost 90 per cent expressed pluripotent stem cell markers.

"The other difference is when you use conventional technologies, you get very small colonies per embryo, so you can get up to about 10,000 cells and then they start differentiating," said Verma. "We get 200,000 cells from each embryo, so it's giving us a lot more cells to work well."

The CRC has filed an international patent application on the new technique, and Verma believes that it may apply to all species, not just bovine.

"In the short term there are many minor applications in understanding development and disease resistance and disease models where large animal studies can play a part," said Verma. "In the long run, if you can produce gametes from stem cells and select them it can really make quite a difference."

For example, if gametes could be produced from stem cells, genetic improvement could potentially be sped up in the dairy herd. "To prove a dairy sire takes six years and about $1 million per sire --that's proven. If you could actually produce gametes from stem cells you could reduce that time for a year or two which would be a huge difference for the dairy industry".