Researchers: Rejuvenation of immune cells could improve cancer, HIV therapies

January 04, 2013

THE ASAHI SHIMBUN

Two Japanese research teams said they have rejuvenated immune cells by using technology for induced pluripotent stem (iPS) cells, opening a path to improve therapies to treat cancer and infectious diseases.

A team led by Hiroshi Kawamoto at the Riken research institute and another group led by Hiromitsu Nakauchi, professor of medical science at the University of Tokyo, published their papers in the Jan. 4 edition of the U.S. science journal Cell Stem Cell.

The two teams focused on immune cells called T cells. With their antenna-like molecules, T cells can detect antigens of cancerous or virus-infected cells and kill them.

In conventional immune therapy, the number of T cells capable of recognizing cancerous and infected cells are increased outside the patient's body and returned to it.

But the effects of the conventional method are limited because there are only a small number of T cells in the body, and they have a short life span of about one to two weeks. That means that many of the T cells are already nearing the end of the short lives.

Kawamoto’s team put genes called “Yamanaka factors” into T cells taken from patients with malignant melanoma, a type of skin cancer, to reprogram the cells into iPS cells. The team then returned the iPS cells into T cells through the process of differentiation.

The Yamanaka factors to create iPS cells were discovered by researchers led by Kyoto University professor Shinya Yamanaka, who won a Nobel Prize in 2012.

The Riken researchers said they found 98 percent or more of the resulting cells were capable of detecting antigens of cancer cells, and that the regenerated T cells were in a healthy newborn state.

The researchers said this new method solves the problem of T cells existing in such small numbers. From such iPS cells, the researchers said they can create tens of thousands of times the number of T cells taken from the human body.

“The next step is to confirm whether the regenerated T cells attack cancer cells alone and do not harm healthy cells,” Kawamoto said.

The researcher is planning to test the method’s effectiveness with other types of cancer antigens.

Meanwhile, the team led by Nakauchi succeeded in a similar experiment with T cells capable of killing HIV-infected cells. The researchers also said they confirmed the rejuvenation of T cells.

“This will lead to a stronger immune therapy,” Nakauchi said.

Observers say the findings could expand the application of iPS cell technology, which is now attracting attention in the fields of organ regeneration and drug development.

(This article was written by Hiroshi Ishizuka and Kayoko Geji.)

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