They call it a ‘transplantable form’ of Alzheimer’s disease. Canadian medical biologists published an article in a professional journal last week Stem Cell Reports, in which they describe how mice can develop Alzheimer’s-like symptoms after receiving a transplant of bone marrow from genetically modified donor mice. For example, recipients score less well on cognitive tests. Based on these findings, the researchers suggest that human donor material – from bone marrow to organs and blood – should also be carefully checked for Alzheimer’s-related gene variants. And that rubs several other scientists the wrong way.
Magazine Science says the American neuroscientist Lary Walker, who emphasizes that neither the donor mice nor the recipients actually have Alzheimer’s. “They only show certain symptoms that require further investigation.” People who need a bone marrow transplant should absolutely not be deterred by the research.
Medical microbiologist Hans Zaaijer, head of the Blood-Borne Infections department at Sanquin Research, is also critical. “As co-guardian of Dutch blood safety, I have my thoughts about this,” he explains by telephone. “Already in the first sentence they write that the risk of communicable diseases is systematically underestimated in blood transfusions and organ and tissue donations. None of that is true. We are prepared for such situations and monitor so strictly that it has even been suggested that things could be lowered a notch.”
Also read
Alzheimer’s disease can be transmitted via contaminated growth hormone
At a young age
In addition, Zaaijer also emphasizes that the study concerns one specific variant. “If you read carefully, it is about a gene that causes a certain family member early onsetform, so a hereditary variant of Alzheimer’s that starts at a young age. Genetic abnormalities are in genes and they are in cells, so it does not surprise me that if you place a cell with that abnormality from one mouse into another mouse, you will also encounter that gene there and that this may lead to abnormalities.”
He calls the recent article more interesting Nature Medicine about patients who were treated between 1959 and 1985 with growth hormone that was contaminated with pathogenic proteins and who subsequently developed Alzheimer’s-like symptoms. Infectious proteins also play a role in Creutzfeldt-Jakob disease and the ‘mad cow disease’ variant. “But this is strictly monitored.” For reassurance, he cites a large Swedish-Danish study from 2016, which shows no causal link between blood transfusions and neurodegenerative diseases (such as Alzheimer’s). “As far as we know, Alzheimer’s disease has never been transmitted via transfusion.”
Back to the mouse study in Stem Cell Reports: here too, the researchers ultimately pull some punches. For example, they emphasize that the mouse results cannot be simply translated to humans, and that the Alzheimer’s variant studied is very rare – it only occurs in two families worldwide.
To share
Email the editor
