The scientists looked at 400 different microRNAs in both embryonic and induced pluripotent cells. Humans have approximately 1,000 microRNAs.
Pluripotent stem cells have some similarity to cancer cells. They are immortal. They self-renew. Tumors keep dividing. So do pluripotent stem cells. "That's their property, self-renewal, proliferation," said Kosik. "And that's what cancer does. How can it be that pluripotent stem cells can self-renew and are not cancer, but cancer cells self-renew and are cancer? Cancer lacks any control over itself. What's the difference?"
The scientists included studies of 40 types of differentiated body cells, in the microRNA testing. They found that the microRNA was very different in the cancer cells and the differentiated cells. This was not a surprise.
The surprise was that when looking at pluripotent cells, some are more more similar to cancer and others are less similar.
"One of the big problems that people worry about in the use of stem cells for the repair of body parts, is whether or not you are going to be creating cancer," said Kosik. "That's a big worry one of the major worries. So if we have a way here, and this we don't know yet, but if these microRNA profiles that look like cancer indicate a propensity toward cancer, then that would be very nice to know. But we don't know that yet."
He explained two possibilities: If doctors are going to use stem cells for body repairs, they don't want them to be cancerous, but they do want them to have enough growth potential that they will really make a difference. "So maybe they should look a little bit like cancer," said Kosik. "On the other hand, you don't want them to become a tumor. So maybe you want them to look a little less like cancer. At this point you could make either argument. We just don't know."
Scientists at UCS
|Contact: Gail Gallessich|
University of California - Santa Barbara