Scientists are enthusiastic about the potential of embryonic stem cells for treating a variety of diseases.
But these cells are controversial because obtaining them means destroying an embryo.
Now, scientists in New York say they may have found cells that are just as promising, but do not start with an embryo.
A few years ago, scientists in Japan said they had found stem cells with remarkable properties in the testes of adult mice. Not only could the stem cells turn into sperm, but they could, under the right conditions, be turned into any cell you like — skin, muscle, brain, you name it.
But Marco Seandel says there was a problem.
"These are relatively rare cells mixed in with a huge number of other different types of cells, some closely related, some much different," says Seandel, a researcher at Memorial Sloan-Kettering Cancer Center in New York.
"What one needs is a very efficient way to pull out the ones that one's interested in," he says.
So, Seandel and his colleagues at Weill Cornell Medical College set out to find a way to distinguish these cells from all the others in the testes. As they report in Thursday's issue of the journal Nature, they found one. All these cells have a protein called GPR125 poking out of them.
"Having the GPR125 as a marker is a very important tool for fishing these cells out of what is otherwise a very complicated mixture," says George Daley, a stem cell biologist at Children's Hospital Boston.
But finding GPR125 in mice just the start.
"There's a lot of unanswered questions, the most key of which is can they replicate this with human cells," says Daley.
If they can, it would open up some interesting possibilities for therapies.
"One of the more grandiose goals would be to take a testes biopsy, put these cells in culture, and then coax them to become whatever type of tissue a person might need" to treat a disease, he says.
That is for the future. For now, Seandel says he and his colleagues are getting ready to begin their search for these special cells in human beings. He admits finding volunteers to donate testicular tissue may be challenging, although he says he has been told there is very little discomfort.
So does that mean Seandel and his colleagues are planning to donate their own tissue?
"We we've talked about that here in the lab. No one has volunteered, so far," he admits.
Seandel says the goal for the moment is to perfect their techniques for obtaining these cells from mice.