RESUMO
Degenerative diseases of the brain have proven challenging to treat, let alone cure. One of the treatment options is the use of stem cell therapy, which has been under investigation for several years. However, treatment with stem cells comes with a number of drawbacks, for instance the source of these cells. Currently, a number of options are tested to produce stem cells, although the main issues of quantity and ethics remain for most of them. Over recent years, the potential of induced pluripotent stem cells (iPSCs) has been widely investigated and these cells seem promising for production of numerous different tissues both in vitro and in vivo. One of the major advantages of iPSCs is that they can be made autologous and can provide a sufficient quantity of cells by culturing, making the use of other stem cell sources unnecessary. As the first descriptions of iPSC production with the transcription factors Sox2, Klf4, Oct4 and C-Myc, called the Yamanaka factors, a variety of methods has been developed to convert somatic cells from all germ layers to pluripotent stem cells. Improvement of these methods is necessary to increase the efficiency of reprogramming, the quality of pluripotency and the safety of these cells before use in human trials. This review focusses on the current accomplishments and remaining challenges in the production and use of iPSCs for treatment of neurodegenerative diseases of the brain such as Alzheimer's disease and Parkinson's disease.