stem cells

“Young” Immune Cells Show Promise in Reversing Signs of Alzheimer’s and Aging

Researchers at the Cedars-Sinai Board of Governors Regenerative Medicine Institute have demonstrated that infusing “young” immune cells can improve cognitive function and brain health in aging and Alzheimer’s disease mouse models.The study, published August 24, 2025, in Advanced Science (DOI: 10.1002/advs.202417848),suggests a potential new therapeutic avenue for age- and Alzheimer’s-related cognitive decline.

“our approach was to use young immune cells that we can manufacture in the lab-and we found that they have beneficial effects in both aging mice and mouse models of Alzheimer’s disease,” stated Clive N. Svendsen, a Governor’s Regenerative Medicine Institute senior author of the study.

The team focused on mononuclear phagocytes, immune cells responsible for clearing harmful material throughout the body, whose effectiveness diminishes with age. To create younger versions of these cells, they reprogrammed human adult cells into induced pluripotent stem cells, effectively resetting them to an early embryonic state. These stem cells were then developed into new mononuclear phagocytes and infused into aged mice and mice exhibiting Alzheimer’s-like symptoms.

Results showed critically important improvements in memory assessments for mice receiving the young cells compared to untreated mice. Importantly, these mice also maintained higher numbers of mossy cells within the hippocampus, a brain region crucial for learning and memory.

“The numbers of mossy cells decline with aging and Alzheimer’s disease,” explained Alexendra Moser, PhD, a project scientist in the Svendsen Lab and lead author of the study. “We did not see that decline in mice receiving young mononuclear phagocytes, and we believe this may be responsible for some of the memory improvements that we observed.”

Further analysis revealed healthier microglia – another type of immune cell in the brain – in the treated mice. Microglia utilize long, thin branches to detect and remove debris and damaged cells, but these branches typically shrink with age and in Alzheimer’s disease. The therapy preserved the length and health of these branches.

While the exact mechanism of action remains under investigation,the young mononuclear phagocytes did not appear to directly enter the brain. Researchers hypothesize the cells may be exerting their effects indirectly, possibly by releasing anti-aging proteins or extracellular vesicles (tiny particles capable of entering the brain). Another possibility is that the cells absorb pro-aging factors from the bloodstream, preventing them from reaching the brain.

“Because these young immune cells are created from stem cells, they could be used as personalized therapy with unlimited availability,” said jeffrey A. golden, MD, executive vice dean for Education and Research. “These findings show that short-term treatment improved cognition and brain health, making them a promising candidate to address age- and Alzheimer’s disease-related cognitive decline.”

The study was supported by the Worldwide Sunlight Foundation, the Cedars-Sinai Center for Translational Geroscience, and the Cedars-Sinai Board of Governors regenerative Medicine Institute. Ongoing research is focused on elucidating the protective mechanisms to pave the way for potential clinical trials in patients.