Scientists find evidence in mice that hereditary Alzheimer’s disease may be contagious

A new study this week points to potential transmission risks of Alzheimer’s disease. Researchers have found evidence in mice that a genetic neurological disease can be inherited through bone marrow donation. While this danger has not yet been proven in humans and is likely to be rare if it occurs, the authors say more research is needed to investigate this possibility.

The study was led by scientists at the University of British Columbia. They are interested in studying cells that produce amyloid precursor protein (APP), a protein that has several important functions but can also be converted into amyloid beta, a protein thought to drive Alzheimer’s disease. acting protein. In people with Alzheimer’s disease, misfolded and damaging amyloid beta proteins accumulate in the brain, eventually forming clumps of deposits called plaques (a similar process occurs with tau).

in most cases Alzheimer’s disease It is caused by a combination of factors, such as age-related changes in the brain. But genetic mutations are known to make people more likely to develop the disease, often at an earlier age than normal. Some of these mutations involve genes that regulate APP production in cells. However, the cells that produce APP are found not just in the brain but throughout the body, including in our bone marrow. So the authors, led by immunologist Wilfred Jefferies, were curious about the possibility that these external cells could also contribute to Alzheimer’s disease.

“So we wanted to know if injecting bone marrow from diseased mice into the blood of normal mice could trigger familial Alzheimer’s disease in mice,” Jeffries told Gizmodo in an email. .”

The team first bred mice with a defective version of the human APP gene, which causes them to develop Alzheimer’s disease. They then transplanted bone marrow from these mice into two other groups of mice: mice with a normal APP gene and mice with no APP gene at all. After transplantation, both groups of mice developed symptoms of cognitive impairment and telltale signs of Alzheimer’s disease, such as plaque buildup in the brain. However, those mice without the APP gene became sick faster than expected, showing symptoms at an average of six months of age (both the original APP-carrying mice and the normal APP-carrying mice began to show symptoms around nine months of age ).

survey results, publish Thursday at stem cell reportJeffries said this seemed to prove that “mutated genes in donor cells can be transferred and cause” Alzheimer’s disease. While the mice without APP worsened more quickly, the results suggest that even healthy individuals may be at risk from this infection route.

Other scientists have find evidence Alzheimer’s disease can be spread from person to person, although only under very rare and specific conditions, such as donating contaminated human growth hormone extracted from cadaver brains (a practice that has long since ended). If there is indeed a risk of familial Alzheimer’s disease being transmitted through a bone marrow transplant, the risk is likely to be low.

But Jeffries said that based on their findings, the authors do “urge for further investigation of this phenomenon.” “We also advocate for screening of human donors of blood, tissue, organs and stem cells to prevent the inadvertent spread of disease during blood product transfusions and cell therapies.”

The author plans to continue investigating the matter himself. They hope to better understand how these donated APP-producing stem cells, which can only convert into blood cells or platelets, but not into neurons, go on to trigger Alzheimer’s disease. They also hope to study whether other types of transplants can transmit the disease, or whether Alzheimer’s can be treated by transplanting normal cells into people with the disease.Early animal trials involving stem cells found some This approach has promising results.

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