Researchers injected mouse brains with a growth hormone tainted with amyloid-β, a protein implicated in Alzheimer’s disease, and saw it accumulate. The study, published yesterday (December 13) in Nature, bolsters the hypothesis that amyloid-β may be spread from one person to another under rare conditions from contamination, but does not show the protein to be contagious.
The idea that the protein could be transferred between people gained traction after a 2015 study found unusually large deposits of amyloid-β in the autopsied brains of four people who had received injections of growth hormone as children in the United Kingdom. Thousands of children received growth hormone derived from cadavers to treat stunted growth between 1958 and 1985, The Guardian reports.
The new study confirms that some growth hormone back then was contaminated with amyloid-β. The researchers then injected the contaminated hormone into the brains of mice "genetically engineered to be susceptible to amyloid pathology," according to Nature's news report. These mice grew plaques, chunks of amyloid-β protein that are found in the brain of Alzheimer’s patients. Taken together, the findings suggest that amyloid-β can “seed” the protein’s buildup in human’s brains too.
Synthetic growth hormone has since replaced that derived from cadavers. But to prevent this sort of spread in the future, The Guardian reports, surgeons should decontaminate tools used for brain surgery more thoroughly.