Application of human induced pluripotent stem cells for modeling and treating neurodegenerative diseases.

The advent of human induced pluripotent stem cells (hiPSCs), reprogrammed in vitro from both healthy and disease-state human somatic cells, has triggered an enormous global research effort to realize personalized regenerative medicine for numerous degenerative conditions. hiPSCs have been generated from cells of many tissue types and can be differentiated in vitro to most somatic lineages, not only for the establishment of disease models that can be utilized as novel drug screening platforms and to study the molecular and cellular processes leading to degeneration, but also for the in vivo cell-based repair or modulation of a patient's disease profile. hiPSCs derived from patients with the neurodegenerative diseases amyotrophic lateral sclerosis, Parkinson's disease, Alzheimer's disease and multiple sclerosis have been successfully differentiated in vitro into disease-relevant cell types, including motor neurons, dopaminergic neurons and oligodendrocytes. However, the generation of functional iPSC-derived neural cells that are capable of engraftment in humans and the identification of robust disease phenotypes for modeling neurodegeneration still require several key challenges to be addressed. Here, we discuss these challenges and summarize recent progress toward the application of iPSC technology for these four common neurodegenerative diseases.