REGENERATION OF NEURONS
For almost one century, it has been the mantra of biology that brain cells do not regenerate. In a startling discovery that could have profound impact on treating brain injuries and neurodegenerative Parkinson’s and Alzheimer’s diseases, scientists at Princeton University have discovered that new neurons are continually being added to the brain of adult monkeys [(Science, 286, 5439 (1999)].
The neurons are added to the cerebral cortex which is the part of the brain responsible for higher level decision making and learning. The formation of new nerve cells, a process known as neurogenesis, takes place in three areas of the cerebral cortex:
- Prefrontal region which controls decision making
- Inferior temporal region which plays a role in visual recognition
- Posterior parietal region which plays a role in 3D representation
This discovery is likely to translate to humans because monkeys and humans, as fellow primates, have fundamentally similar brains.
Neuron and Neural Stem Cells Neurons do not divide within the central nervous system (CNS). However, brain has another class of cells known as Neural Stem Cells (NSCs), which are multipotent cells with limited ability to differentiate to replace lost, injured or dead neurons. The hallmark characteristic of NSCs is their ability to proliferate and generate multiple cell lineages such as neurons, astrocytes and oligodendrocytes. NSCs are considered adult stem cells because of their pre-destined role which is to replace injured or lost neurons. Contrary to an embryonic stem cell, which is not limited to a particular cell fate, NSC is limited to differentiation into a neuron.
Case for Clearing Toxic Protein Aggregates from the Brains of Parkinson’s Patients Degeneration of dopaminergic neurons is a major pathology observed in Parkinson’s disease (PD), however, non-dopaminergic systems are also affected. Although some drugs can provide short-term symptomatic relief for motor symptoms, effective therapies for non-motor symptoms such as dementia are lacking and disease progression cannot be counteracted. Neural stem cell therapy can potentially be very useful provided the brain is clear of such toxins responsible for killing neurons in the first place. Neurons die in the presence of toxic aggregates of misfolded alpha-synuclein protein. Therefore, for any cells based therapy to work, toxin has to be cleared from the brain.
Early detection and therapeutic intervention are fundamental for successfully treating any disease including PD. The SDBC has developed a potential diagnostic PET ligand for early diagnosis and a therapeutic agent for treatment of PD. The Company believes firmly that its technology that has shown tremendous promise in animal model will one day be useful in treating Parkinson’s patients.