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Researchers around the world are looking for ways to repair brain damage by activating the brain's own stem cells or implanting stem cells from external sources.
Every year, thousands of Canadians suffer brain damage from head injuries, strokes and tumours. These problems can lead to neuronal loss and result in a wide range of disabilities such as reduced mobility, memory loss or impaired reasoning.
At NRC, University of Ottawa PhD candidate Anna Jezierski studies the regenerative potential of human amniotic fluid cells in the brain, under the supervision of Dr. Mahmud Bani and Dr. Andree Gruslin.
"Injury, stroke and tumour excision all leave behind a cavity in the brain," explains Dr. Mahmud Bani, a researcher at the NRC Institute for Biological Sciences and an adjunct professor at the University of Ottawa's Faculty of Medicine. "The larger the cavity, the greater the number of neurons affected."
The human brain can reorganize itself in response to an injury by mobilizing neural stem cells toward the damaged site to fill the gap. But the brain's capacity for self repair is limited. As a result, researchers around the world are looking for ways to further activate the brain's own stem cells or implant stem cells from external sources to repair brain damage.
In a project initiated at the Institute by Dr. Marianna Sikorska, Dr. Bani leads an NRC team that is developing brain repair methods involving "neuro-scaffolds." These biocompatible, biodegradable polymers can be seeded with stem cells and then implanted into the injured part of the brain.
Did you know?
Neurotrophic factors are proteins that promote the growth and development of young neurons and the maintenance of mature neurons in the brain and spinal cord.
"Why not inject stem cells directly into the brain?" asks Dr. Bani. "It's because injected cells rarely develop a functional connection with the damaged host tissue or facilitate tissue reconstruction." But with the help of a neuro-scaffold, he says, stem cell-derived neurons can be held in place until they grow and attach to the surrounding brain tissue.
So far, the research team has successfully implanted neuro-scaffolds containing neural stem and progenitor cells from mouse embryos into adult mice, and has seen "very nice neural regeneration." However, Dr. Bani and his colleagues would prefer to repair brain injuries using a more accessible source of human stem cells that lacks major ethical concerns, such as amniotic fluid. "The benefit of amniotic fluid cells is you can deliver proteins called 'neurotrophic' factors to the brain. You can also genetically program amniotic fluid cells and utilize them to deliver a range of beneficial factors to the brain," he says.
Ten weeks after receiving a neuro-scaffold, a mouse brain (right) shows more tissue regeneration than a brain that did not receive the implant. The neuro-scaffold was designed by Dr. Abdellah Ajji of the NRC Industrial Materials Institute in Montréal.
Toward this goal, the team has implanted neuro-scaffolds containing human amniotic fluid cells into brain-injured mice, with some success. "We are making progress at protecting injured brain cells from dying as well as enhancing motor recovery," says Dr. Bani. "However, in terms of regenerating neurons in the damaged region, our research is ongoing. We're still trying to fine-tune our methods." 
A sustainable source of stem cells
In Canada, many pregnant women over the age of 35 undergo amniocentesis to test for Down's syndrome or other genetic disorders. During amniocentesis, a small volume of amniotic fluid is extracted from the mother's uterus. The fluid contains cells originating from several fetal tissues, including skin. These cells are then grown and genetically analyzed to identify potential abnormalities.
Afterwards the cells are normally discarded, but Dr. Bani's team asks expectant parents for permission to use their amniotic fluid in research. "Through our collaboration with Dr. Andree Gruslin at the Ottawa Hospital, we bring the cells to NRC, characterize their cellular and molecular profiles, place them on neuro-scaffolds and implant them into mice brains."
