The role of induced pluripotent stem cells in regenerative medicine: neurodegenerative diseases

Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and Friedreich's ataxia are the most common human neurodegenerative diseases pathologically characterized by a progressive and specific loss of certain neuronal populations. The exact mechanisms of neuronal cell death in these diseases are unclear, although some forms of the diseases are inherited and genes causing these diseases have been identified. Currently there are no effective clinical therapies for many of these diseases. The recently acquired ability to reprogram human adult somatic cells to induced pluripotent stem cells (iPSCs) in culture may provide a powerful tool for in vitro neurodegenerative disease modeling and an unlimited source for cell replacement therapy. In the present review, we summarize recent progress on iPSC generation and differentiation into neuronal cell types and discuss the potential application for in vitro disease mechanism study and in vivo cell replacement therapy.