The study of Parkinson's disease (PD) is challenging due to the inaccessibility of affected human midbrain dopaminergic (mDA) neurons on which to base experimental research, and the rarity of animal models that follow the major disease characteristics. Despite this, it has been uncertain whether the involved mechanisms would also occur in human neurons affected by the disease. Consequently, molecular pathways underlying this pathology are still not well-defined. Although the majority of PD cases are sporadic, some rare familial forms of this disease have led to the discovery of PD-linked genes. This discovery was imperative for deciphering the cellular and molecular mechanisms of PD (Gasser, 2007; Schulz, 2008) and for creating transgenic animal and cellular models expressing these PD- associated genes. Recent development in PD research generated different neuronal cell types, which were previously inaccessible, by deriving PD-linked iPS cell lines that could be used for autologous transplantation (Park et al., 2008a; Soldner et al., 2009). Such approaches present exciting promises to elucidate the etiology of PD and develop novel potential therapeutics (Byers et al., 2012; Table 1).
