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Blood stem cells could help protect brain against damage caused by radiation therapy.
Posted On: April 20, 2020
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Learning and memory are two related cognitive processes. New knowledge is acquired through learning and then retained and reconstructed through memory.
For older adults, radiotherapy for brain cancer is a double-edged sword.
Radiotherapy, which involves the delivery of high doses of radiation, is a widely used and effective way of killing cancer cells in the brain. However, it can also damage and kill healthy brain cells, leading to deficits in memory and learning. These negative effects are more pronounced in older adults.
A new study from UHN and the Hospital for Sick Children (SickKids) reveals a new approach that could help prevent impaired memory and learning after radiotherapy. The study was led by Dr. Ren-Ke Li, a Senior Scientist at UHN’s Toronto General Hospital Research Institute, and Drs. Lu-Yang Wang and Zhenping Jia, Senior Scientists at SickKids.
The new approach involves hematopoietic stem cells (HSCs), which reside in the bone marrow. HSCs are responsible for producing all of the different types of cells found in the blood.
Using an experimental model of radiotherapy, the researchers discovered that HSCs provided intravenously could prevent radiation-induced deficits in memory and learning. They showed that injected HSCs populated the recipient’s bone marrow and produced new cells, many of which migrated into the brain. In brain tissues, the cells developed into microglial cells, which are implicated in learning and memory, and prevent loss of the brain cells.
Interestingly, only HSCs from young donors displayed neuroprotective properties. The researchers found that microgial cells derived from these ‘young’ HSCs activated memory genes in the surrounding brain tissue, produced neuroprotective factors and promoted a process known as long-term potentiation, which underlies learning and memory.
“Our findings demonstrate that HSCs from young donors may provide a novel therapeutic avenue for the treatment of cognitive deficits that arise after irradiation of the aged brain. In addition, these young HSCs could potentially be used to prevent memory loss or restore it in older adults,” says Dr. Li.
This work was supported by the Canadian Institutes of Health Research, the Ontario Research Fund and the Toronto General & Western Hospital Foundation. RK Li hold a Tier 1 Canada Research Chair (CRC) in Cardiac Regeneration. LY Wang holds a Tier 1 CRC in Brain and Behaviour. Z Jia holds a Tier 1 CRC in Synaptic Plasticity and Brain Disorders.
Wlodarek L, Cao F, Alibhai FJ, Fekete A, Noyan N, Tobin SW, Marvasti TB, Wu J, Li SH, Weisel RD, Wang LY, Jia Z, Li RK. Rectification of radiotherapy-induced cognitive impairments in aged mice by reconstituted Sca-1(+) stem cells from young donors. J Neuroinflammation. 2020 Feb 7. doi: 10.1186/s12974-019-1681-3.