A new kind of stem cells developed by UW-Madison researcher James Thomson performs like his old kind in a lively way.

The new cells can be turned into heart cells that beat in a lab dish, other scientists on campus have shown. The achievement could lead to a better understanding of heart disease and therapies crafted from the skin of patients with heart problems.

"It's encouraging for the development of personalized medicine," said Dr. Tim Kamp, a UW-Madison cardiologist, who coaxed the new stem cells to become heart cells.

Kamp and scientists at other institutions had converted human embryonic stem cells, available since 1998, into heart cells.

Now Kamp and his colleagues at UW-Madison are the first to report that they have directed induced pluripotent stem cells — or iPS cells, the new stem cells announced in 2007 — to become the three main types of heart muscle cells. The researchers also showed that the new kind of heart cells act like the old kind.

"At a functional level, they seem to behave very similarly," said Kamp, whose report on the new work is in the new issue of the journal Circulation Research.

"It's a significant advance," Dr. Dan Garry, a cardiologist at the University of Minnesota, said of Kamp's research.

Thomson was the first scientist, in 1998, to extract and grow stem cells from human embryos. Researchers have been using the master cells, thought capable of becoming all of the body's 220 cell types, to better understand and develop treatments for a variety of diseases. Obtaining the cells requires the controversial destruction of days-old embryos, usually leftover from fertility clinics.

Thomson and campus scientist Junying Yu, along with a competing team led by Japanese researcher Shinya Yamanaka, announced the creation of iPS cells in 2007. The scientists placed four select genes into skin cells and reprogrammed the cells back to their embryonic state. So far, iPS cells appear identical to embryonic stem cells, even though no embryos are used.

Kamp found that iPS cells can become heart cells as well as embryonic stem cells can, morphing into the three main types of heart muscle cells and beating in a dish after growing together for about eight days. Their electrical signals also are similar, he said.

But heart cells made from both kinds of stem cells have limitations. Only a fraction of the stem cells become heart cells, Kamp said. The heart cells could cause heart rhythm problems or cancer if transplanted into patients, he said, but researchers are working to address those issues.

"Things are moving very fast in this area," Kamp said. "But we still have a lot of work to do."

Kamp's collaborators on the research, in addition to Thomson and Yu, were Jianhua Zhang, Gisela Wilson, Andrew Soerens, Chad Koonce and Sean Palecek.