Says a Japanese research team

Jun 2, 2010 07:47 GMT  ·  By
Generation of iPS cells harboring NKT cell-specific rearranged T cell receptor loci
   Generation of iPS cells harboring NKT cell-specific rearranged T cell receptor loci

Scientists in Japan announce the development of a new biotechnology method of transforming induced pluripotent stem cells (iPS) into natural killer T (NKT) cells. The latter class of structures is very well-equipped for destroying cancer tumors, and oncologists have over the past few years tried to develop methods of boosting their numbers, as an alternative treatment to radiotherapy and chemotherapy. With the successful, world-premiere demonstration of this differentiation, the research team at RIKEN again reaffirmed its status as the leading research organization in the Asian nation. Japan itself has always been a pioneer in stem cell research.

One of the things that generally allows for cancer to develop is the fact that NKT cells can usually be found in very small numbers in patients with tumors. One of the most promising therapies in combating this disease is the injection of the glycolipid α-GalCer. But, while this chemical is extremely well suited for the activation of NKT cells, it has very few results on the final outcome of cancer, given the small number of anti-tumor cells. It is the RIKEN team's hope that, by developing a method of producing additional immune cells, the α-GalCer-based therapy could become many times more efficient.

The group decided to focus its attention on iPS because these cells have the ability to differentiate into any other type of cell in the human body. By controlling their environment, researchers can make them turn into bone cells, epithelial cells, and so on. However, when the investigators tried to use these stem cells, they stumbled upon a problem. During the differentiation process, the rearrangement of genes in the NKT cells reduced the overall number of cells with the desired ability to fight tumors. Still, the Japanese team found a way around this obstacle.

The group used fully-mature NKT cells as a starting point, deriving their iPS by reverting these cells to their original, stem state. This circumvented the rearrangement of the genes issue, allowing them to produce larger quantities of tumor-killing NKT cells. The active element in these cells is the TH1 cytokine called IFN-γ. This chemical activates the actual anti-tumor function in the NKT cells, the team reports in the upcoming issue of the esteemed scientific Journal of Clinical Investigation. This therapeutic approach was thus far only demonstrated in unsuspecting lab mice, but the method holds great promise for humans as well.