NEW YORK —  A groundbreaking study by the Children's Hospital of Pittsburgh (search) could add a new voice to the controversial stem cell debate.

The study found that adult stem cells might be just as medically useful as embryonic stem cells.

"This find is very, very mind-boggling," said Dr. Johnny Huard (search), director of the Growth and Development Laboratory at Children's Hospital of Pittsburgh.

Dr. Huard's team hypothesized that adult stem cells could live and multiply for about 25 days. The team was stunned to find the cells lasted 10 times that long — multiplying just as well as embryonic ones.

"The difference between adult and embryonic stem cells is not that big because what we found is that adult can grow for a long time," Huard said.

Dr. Huard's team conducted its research by allowing adult stem cells to develop in mice. However, if these findings work as well in humans, doctors could use adult stem cells to repair muscle, tissue and bone injuries — though they're not likely to treat nerve diseases like Lou Gehrig's Disease (search) and Parkinson's Disease (search).

But other scientists who work with adult stem cells say they are no substitute for embryonic ones.

"If we hope to get patients out of bed, out of wheelchairs, leading high-quality lives, we've got to investigate and potentially use both adult and embryonic stem cells," said Dr. Ira Black, neuroscience researcher at the Stem Cell Institute of New Jersey (search).

Opponents of embryonic stem cell research say the possibility of using both embryonic and adult stem cells is discouraging.

"It is quite a breakthrough. But, sadly, proponents of embryonic stem cells are married to the idea that we must experiment on little human beings. I expect they won't admit they were wrong," said Wendy Wright, senior policy director for Concerned Women for America (search), which aims to promote biblical values.

As research on adult stem cells continues, it seems new discoveries have no effect on quelling the debate.

Click in the box near the top of the story to watch a report by FOX News' Alisyn Camerota.