Medium spiny neurons for transplantation in Huntington's disease

Cell-replacement therapy for Huntington's disease is one of very few therapies that has reported positive outcomes in clinical trials. However, for cell transplantation to be made more readily available, logistical, standardization and ethical issues associated with the current methodology need to be resolved. To achieve these goals, it is imperative that an alternative cell source be identified. One of the key requirements of the cells is that they are capable of acquiring an MSN (medium spiny neuron) morphology, express MSN markers such as DARPP-32 (dopamine- and cAMP-regulated phosphoprotein of 32 kDa), and function in vivo in a manner that replicates those that have been lost to the disease. Developmental biology has progressed in recent years to provide a vast array of information with regard to the key signalling events involved in the proliferation, specification and differentiation of striatal-specific neurons. In the present paper, we review the rationale for cell-replacement therapy in Huntington's disease, discuss some potential donor sources and consider the value of developmental markers in the identification of cells with the potential to develop an MSN phenotype.