OSAKA, Jan. 27-- A research team of Japan's Osaka University has announced that it has proved myocardial cells developed from induced pluripotent stem (iPS) cells could assimilate with heart tissues of rats and function continuously, which marks a big step towards clinical research of treating human heart diseases with iPS cells.

The team said it had cooperated with National Cerebral and Cardiovascular Center to transplant iPS-derived myocardial cell sheets to rats with myocardial infarction, and observed the cells one month later with help of X-rays from SPring-8, the world's largest third-generation synchrotron radiation facility located in Hyogo Prefecture, western Japan.

The result showed on a molecular level that the actin and myosin of the transplanted cells functioned well in contractions of the heart tissues, which means the transplanted cells have become an integral part of the heart tissues of the rats.

This is the first time iPS-derived cells have been proved assimilable with the myocardial tissue, though animal tests have shown iPS-derived cells could improve function of the heart previously, said the researchers.

The discovery will be a step towards clinical research of treating human patients with severe heart failure by transplanting iPS-derived myocardial cell sheets to them, according to the team.

First developed by Nobel Prize-winning Kyoto University professor Shinya Yamanaka in 2006, iPS cells are a type of stem cells that can be generated directly from adult cells.

As pluripotent stem cells can grow into various human body tissues, iPS cells hold great promise for regenerative medicine. Clinical research has been under way in Japan on using iPS cells to remedy retinal degenerative disease.