Brain diseases can have a large impact on patients and society, and treatment is often not available. A new approach in which somatic cells are reprogrammed into induced pluripotent cells (iPS cells) is a significant breakthrough for regenerative medicine. This promises patient-specific tissue for replacement therapies, as well as disease-specific cells for developmental modeling and drug treatment screening. However, this method faces issues of low reprogramming efficiency, and poorly defined criteria for determining the conversion of one cell type to another. Cells contain epigenetic "memories" of what they were that can affect reprogramming. This book discusses the various methods to reprogram cells, the control and determination of cell identity, the epigenetic models that have emerged and the application of iPS cell therapy for brain diseases, in particular Parkinson's disease and Vanishing White Matter (VWM).​