Researchers from the Purdue Institute for Integrative Neuroscience, Pennsylvania State University, and Jinan University in China have collaborated on a study to restore vision after stroke in mice using gene therapy, a press release from Purdue University said.
A stroke is a medical condition when an artery in the brain is blocked preventing tissues in the area from getting oxygen and nutrients. The oxygen-starved cells die leading to a loss of function. On most occasions, a stroke patient loses the ability to move a part of his body but in many cases, it affects their vision too.
The neuronal network is flexible though and can sometimes repair itself to restore vision in stroke patients. In the past, scientists have attempted stem cell therapy to restore vision but a patient's immune system can reject these treatments due to immune mismatches. Professor Alexander Chubykin is an expert on neurons and under his guidance, the team decided to use gene therapy instead.
Previous research has shown that a transcription factor, NeuroD1, can activate certain genes that can convert astrocytes into neurons. Astrocytes are cells in the brain and spinal cord that do not carry electrical impulses but protect the neurons - the cells that carry electrical impulses and provide them oxygen and nutrients. Using NeuroD1-mediated gene therapy, these supporting cells can be converted into important information-carrying cells.
The researchers first induced stroke in mice so that it affected the visual centers in the brain and then measured the extent of the vision loss. They then delivered the gene therapy into the affected areas and allowed the transformed cells to be integrated into neural pathways, restoring vision loss.
"We don’t have to implant new cells, so there’s no immunogenic rejection. This process is easier to do than stem cell therapy, and there’s less damage to the brain," said Chubykin in a press release. "We can see the connections between the old neurons and the newly reprogrammed neurons get reestablished. We can watch the mice get their vision back."
The team also measured the responses to a visual stimulus after the intervention and the extent of recovery in the mice. The study published in Frontiers journal states that after therapy, the neurons in the mice regained normal levels of response to light in as little as three weeks. Further research in this area can be used to correcting the loss of motor function in the future, the press release said.