Researchers reverse aging and Alzheimer’s effects in mice

Researchers at Cedars-Sinai have developed lab-made immune cells that improved memory and reversed signs of aging and Alzheimer’s disease in mice, raising hopes for new therapies to fight this cognitive illness. The study, published in Advanced Science, shows how human stem cell-derived immune cells could one day be adapted into treatments for patients.

Previous research has shown that transfusions of blood from young mice could slow cognitive decline in older animals, but such methods are impractical for human use. Instead, the Cedars-Sinai team turned to lab-grown immune cells known as mononuclear phagocytes. These cells normally patrol the body to clear away harmful substances, but become weaker with age.

By using human induced pluripotent stem cells – adult cells reprogrammed into an embryonic-like state – scientists generated “young” versions of mononuclear phagocytes. When infused into aging mice and Alzheimer’s models, the treatment yielded remarkable results.

Improved memory and healthier brain cells

Mice treated with the young immune cells performed better on memory tests than untreated mice. The therapy also preserved “mossy cells” in the hippocampus, a brain region vital for learning and memory. Mossy cells typically decline with age and Alzheimer’s, but remained stable in treated mice.

Researchers also found healthier microglia, the brain’s resident immune cells, in treated animals. Normally, aging and disease cause microglia’s long, thin branches to shrink, reducing their ability to clear debris. In contrast, microglia in treated mice maintained their structure and function.

How the therapy might work

The exact mechanism remains unclear. Interestingly, the young immune cells did not appear to enter the brain directly. Scientists suggest they may work indirectly by releasing anti-aging proteins, sending tiny particles called extracellular vesicles into the brain, or filtering harmful factors out of the blood.

Because the immune cells can be generated from stem cells, they offer the potential for personalized treatments with an unlimited supply. According to the study’s authors, even short-term treatment produced measurable benefits in mice, making this a promising strategy for tackling age-related cognitive decline.

“These findings show that lab-grown young immune cells improved cognition and brain health in aging and Alzheimer’s disease models,” said Dr. Jeffrey A. Golden, executive vice dean for Education and Research at Cedars-Sinai. “They represent a potential breakthrough for future therapies aimed at preserving memory and brain function.”