KANSAS CITY, Mo. (AP) – A University of Missouri-Columbia researcher says he has isolated a rare type of adult stem cell circulating in the blood of pigs and found the stem cells are capable of becoming other cells that form nerves, blood vessels and other kinds of tissues.

So far, molecular biologist Elmer Price has not been able to isolate the cells from human blood, but he believes he eventually will, which could lead to human studies.

Price's research is not related to stem cells from human embryos, a type of research that has sparked debate across Missouri. Missourians will vote in November on a proposed constitutional amendment that would permit all stem-cell research allowed by federal law to be conducted in the state.

"Opponents to embryonic stem-cell research should not use my research as evidence that we don't need embryonic stem cells," said Price, whose report is the cover story of the current issue of the journal Stem Cells and Development. "We really need to pursue both adult and embryonic stem-cell research."

Price said that after he and colleagues Randy Prather and Mike Foley isolated the stem cells, they used different chemical signals to convert them into neurons, bone cells, fat cells and two kinds of blood vessel cells.

The researchers transplanted the nerve cells into the brains and spinal cords of rats, where the cells continued to develop.

"Wow, that's pretty cool," said Mervin Yoder, a stem-cell researcher at Indiana University School of Medicine and vice president of the International Society for Experimental Hematology.

"If these cells are turning into (nerve cells) that are connecting with other neurons, that would be very significant," Yoder said.

Price said the cells appeared to be forming connections to existing nerve cells, but more research will be needed to determine whether the new cells are actually communicating with other nerve cells.

"They look like neurons, they express neuron proteins and when they are inserted into the brain, they migrate around like neurons," Price said.

Stem cells are unspecialized cells able to reproduce themselves or grow into the dozens of kinds of cells that form the tissues of the body. Newly formed embryos contain stem cells that can form into every kind of cell. Adult stem cells are more limited in what type of cell they can become.

Price said he is the first to isolate what he described as a more "primordial" kind of stem cell from blood, a stem cell that is able to form several kinds of cells.

There's only about one such cell in every 100 million blood cells. From each blood draw, Price isolated just one or two of the cells. Over several months, he grew the cells into colonies of about 100 million cells.

"They looked completely different from any other adult stem-cell line ever described in the literature," Price said.

Jaci Winship, executive director of Missourians Against Human Cloning, a group opposing embryonic stem-cell research, called Price's findings one of many examples showing that embryonic stem cell research isn't needed.

"We see continually interesting and exciting breakthroughs in ethical stem-cell research," Winship said.

But Price said adult stem cells do not have the flexibility to treat every disease that may benefit from a stem-cell therapy.

"I think there are so many diseases out there requiring so many cell types, it's just scientifically irrational to say adult stem cells can turn into all of them," he said.

Copyright 2006 by The Associated Press. All Rights Reserved.