Safer method to develop iPS cells found

The Yomiuri Shimbun

A Kyoto University team has developed a method to efficiently generate induced pluripotent stem cells that is less likely to lead to tumor development than the conventional method.

iPS cells are able to transform into the cells of any organ.

The new research, representing a step forward in putting iPS cells into practical use in regenerative medicine, was reported in the online version of the Proceedings of the National Academy of the United States of America on Tuesday.

Generally, iPS cells are produced by introducing four types of genes into skin and other cells. However, one of the genes, c-Myc, can cause cancer.

Although iPS cells can be produced without the c-Myc gene, iPS cell production this way is much less efficient, according to the team.

The researchers replaced c-Myc with L-Myc, a gene with a similar structure, and produced five times more iPS cells than through the conventional method.

The team also found that 70 percent of mice generated with iPS cells using c-Myc developed tumors 400 days after birth, while mice generated with iPS cells using L-Myc were tumor-free after 700 days.

It also discovered that iPS cells using L-Myc functioned almost the same as those using c-Myc and could be used to regenerate cells in organs throughout the body.

The Kyoto University team includes Masato Nakagawa, a lecturer, and Prof. Shinya Yamanaka, who serves as director of the Center for iPS Cell Research and Application.