Regenerative medicine in Parkinson's disease: generation of mesencephalic dopaminergic cells from embryonic stem cells

Cell replacement therapy has been proposed as a means of replacing specific populations of cells lost through trauma, disease or ageing. Parkinson's disease is a progressive neurodegenerative disorder caused by the loss of midbrain dopaminergic neurons. Intrastriatal transplants of human foetal mesencephalic tissue in Parkinson's patients have demonstrated clinical efficacy, but the limited availability of tissue precludes systematic use of this treatment. Human embryonic stem cells are capable of unlimited self-renewal and can differentiate into cells representative of all three germ layers, including cells of the central nervous system. These cells may thus provide a relatively unlimited source of cells for transplantation, if appropriate differentiation protocols to generate highly enriched and specific populations of neural cells can be developed.