Research frontiers: Jack W. Lipton, professor of neurology at Michigan State University’s College of Human Medicine, on Parkinson’s disease
Parkinson's disease is a degenerative brain disorder in which there is a loss of dopamine-producing brain cells in area of the brain called the substantia nigra. The loss of these neurons results tremors in the extremities, stiffness, slowness of movement and impaired balance and coordination. This progressive degeneration results in difficulties with walking, speaking, swallowing and other motor tasks.
While there are drugs available to help treat the symptoms of PD, as the disease progresses, these drugs typically lose their ability to lessen the symptoms over time. This typically results in doctors increasing the dosages of medicines for their patients in order to maintain the original benefit of the drug. However, as dosages increase, so do the incidence and magnitude of drug-induced side effects.
Inducible pluripotent stem cells (IPS) hold great promise as candidates for cell replacement therapy in PD. They are generated by isolating mature cells from a patient (say skin cells, for example) and transforming them into an immature state. This is done using synthetic viruses that insert specific genetic signals that then reset and reprogram the cells. This causes the iPS cells to revert to an immature state. After this, the cells can be grown in a dish where a few of a patient’s cells can be encouraged to divide grow, generating additional iPS cells. These iPS cells can then subsequently be coaxed with additional molecular signaling to become similar to the dopamine neurons which degenerate in PD.
While iPS therapy is by no means a mainstream therapy, great strides have been made in producing stable lines of iPS cells and transforming them into different cell types. Hopefully, studies of this therapy will begin to answer these questions and provide hope to the over one million Americans who suffer from this devastating disease.