New Discoveries in Adult Hippocampal Neurogenesis
A recent discovery in the ability of human neurons to integrate into the visual cortex of rat brains.
Vision-impaired rats recently received surgically grafted human neurons that were able to integrate into their brain structures. While decades of research have demonstrated the possibility of transplanting human cells into rat brains, the success of complete integration of these cells remains a new discovery. This study demonstrated the ability of scientists to cultivate stem cells, graft them into specific sites, and then measure activity by those grafted cells in the host organism.
The first step of this procedure required the cultivation of human neurons derived from stem cells. The stem cell line chosen specifically expressed a green fluorescent protein so these stem cells could continue to be monitored after the surgery. Immunosuppression methods were utilized to prevent the rat from rejecting the tissue. These grafts were connected to the rats’ retina and the rats’ visual system by a synapse, the main site of neuronal communication in the brain. These grafts had a survival of 82.1% after being transplanted into the rat for 3 months, showing that most of the grafts were successful in their surgical transplantation. At the three-month mark, the grafts were integrated into the brain of the host rat with vascularization present, growth of the stem cells occurring, and functioning as synapses with the other neurons of the rat’s brain.
Next, the activity of the grafted cells was measured by scanning for the fluorescent proteins. The researchers were able to measure activity through electrode probes within the neurons of the rats. Neurons fire, releasing electrical impulses as their means of communication, and this provided the researchers with a quantifiable measurement of activity within the neurons. These scans showed that the cell grafts were able to adopt specific functions within the visual cortex of the rats, ultimately repairing portions of the injured rat’s brain as demonstrated by their response to light. This study demonstrates the potential of grafting stem cells into portions of the brain as a repair mechanism for damaged tissue. It shows the possibility, with better-controlled mechanisms, of successful repair of damaged neuronal regions.
Scientists have been studying neuro regeneration to find treatments for the various diseases that cause neuron degradation which the body cannot repair via its own mechanisms. Adult hippocampal neurogenesis, the ability of neurons in the hippocampus (which plays a key role in memory and learning) to regenerate, commonly declines during the early stages of Alzheimer’s. Alzheimer’s acts similarly to a traumatic brain injury, causing damage to the brain through the degradation of neurons. Similarly, stroke patients can experience traumatic brain injuries caused by blood flow being temporarily blocked by a clot in the brain or by blood vessels in the brain bursting and damaging nearby tissue.
This discovery demonstrated how surgical procedures of adding stem cell neurons to certain areas of the brain show promise in restoring function.
