Progress in induced pluripotent stem cell research for age-related neurodegenerative diseases

In 2006, Takahashi et al. established a method for reprogramming somatic cells by introducing definite transcription factors, which enabled the generation of induced pluripotent stem cells (iPSCs) with pluripotency comparable to that of embryonic stem cells. In turn, it has become possible to use these iPSCs for producing various tissues needed for the treatment of neurodegenerative disorders, which have been difficult to obtain from living bodies. This advancement is expected to bring forth rapid progress in the clarification of mechanisms underlying the diseases and discovery of new innovative drugs and lead to rapid progress in regenerative medicine. In recent years, recapitulation and analysis of disease conditions using iPSCs derived from the patients themselves have been reported, and remarkable advances have been made, even for late-onset neurodegenerative disorders. These findings show that the phenotypes of late-onset neurodegenerative disorders can be recapitulated in iPSC-derived neuronal cells, which are reflected the early developmental stages, indicating cellular abnormalities exist from the prenatal period, despite the lateonset diseases. In this review, we summarize the state of iPSCs research in the context of neurodegenerative disorders, discuss the possible ways for understanding the mechanisms underlying neurodegenerative disorders and discovering new drugs, and describe some other aspects of regenerative medicine.