Topics and Speakers Christopher E. Henderson, PhD
| ||||||
Synopsis
Neurodegenerative diseases, such as Parkinson's and ALS, are characterized by the loss of motor neurons. In this lecture, Christopher Henderson, codirector of the Motor Neuron Center at Columbia, elucidates the mechanisms of neuron pathology in such diseases as well as presents two categories of emerging therapies: cell replacement therapy and neuro-protective drugs.
Henderson first provides an overview of ALS and Parkinson's disease, their distinct etiologies, signs, and symptoms. One common feature of ALS and Parkinson's is that they both pose unique and substantial problems to developing therapy. Treatments do exist but they can have severe complications.
Given these daunting therapeutic challenges, Henderson argues that there is a parallel and simultaneous need for neuro-protective drugs (to prevent neuronal loss in the first place) and cell replacement therapy (to replace neurons already lost).
Neuro-protective drugs provide the critical function of slowing down neural degeneration and cell loss. But, as Henderson explains, this is not enough. In Parkinson's, 50% to 70% of neurons in the substantia nigra can be lost before symptoms are declared. This loss is gradual and progressive. Even if neuro-protective drugs are developed, they would most likely only keep the patients at the same clinical stage they were at when they presented to the doctor. Given that the neuronal loss is already profound at that point, even maintaining that initial clinical stage cannot be considered a cure.
How can we prevent neurons from dying? Recently attention has focused on identifying neurotrophic factors, factors that normally keep neurons alive, and using them as biological agents to prevent cell loss in Parkinson's. There are problems and complications with the use of neurotrophic factors that Henderson describes, such as that it is difficult to identify the targets.
Cell replacement therapy restores missing cells and possibly their axonal connections. The promise of cell replacement therapy is that it can give the patient a new start on an irreversible degenerative process, by grafting new cells to increase the number of neurons again cells. This therapy could allow patients to maintain their normal functions.
How can we replace lost neurons? Henderson describes two approaches. First, human fetal brain can be used to prepare neurons and then inject them into the brain. A second technique is to use precursors to neurons, from sources such as the human embryo, to grow more neurons in quantity and then inject those back into the brain. Henderson concludes his presentation by discussing the issues that arise in using and researching such embryonic stem cell derived neurons.
