News · Longevity & Aging
A gene variant linked to long life kept brain blood vessel support cells healthier in mice and lab cells
Most talk about the APOE gene focuses on the version that raises Alzheimer's risk. A study of its protective cousin, APOE2, found it helps cells that guard the brain's blood supply handle fat better.
- This work was done in mice and in human cells grown in the lab, not in people.
- Mice carrying the human APOE2 gene had more pericytes and a tighter blood-brain barrier.
- Lab-grown human pericytes with APOE2 resisted cell aging and built up less amyloid-beta.
- APOE2 cells stored fewer fat droplets and made more proteins that break fats down.
- Adding APOE2 protein improved pericytes carrying the higher-risk APOE3 and APOE4 versions.
If you have heard of the APOE gene, it was probably in connection with Alzheimer’s disease. One version, e4, increases the risk of the late-onset form of the disease. Much less attention goes to its cousin, APOE2, which is linked to lower Alzheimer’s risk and a longer life. A new study, done in mice and in human cells grown in the lab, looked at what APOE2 does for a group of cells that protect the brain’s blood supply.
It found that APOE2 kept those cells healthier, partly by helping them process fat more efficiently. Adding the APOE2 protein even improved cells carrying the other versions of the gene.
What is the APOE gene, and why does its version matter?
APOE makes a protein that helps carry fats, including cholesterol, around the body. MedlinePlus Genetics explains that there are at least three slightly different versions (alleles) of the gene, called e2, e3 and e4, and that e3 is the most common.
The versions carry different risks. MedlinePlus notes that the e4 version of the APOE gene increases an individual’s risk for developing late-onset Alzheimer’s disease. The study’s authors point out that APOE2, by contrast, is associated with reduced Alzheimer’s risk and increased longevity. Why it seems protective has not been clear.
What are pericytes, and what do they do for the brain?
Pericytes are cells that wrap around the brain’s tiniest blood vessels. They help maintain the blood-brain barrier, the tightly controlled boundary that decides what passes from the bloodstream into brain tissue.
When that barrier weakens, substances that should stay out can leak in. The authors note that pericytes have emerged as key contributors to Alzheimer’s disease, which made them a natural place to look for APOE2’s protective effect.
What did APOE2 do in mice?
Writing in the journal Brain, the team studied mice engineered to carry the human APOE2, APOE3 or APOE4 gene in place of their own. Mice with APOE2 had more signs of pericytes in their brains and a more intact blood-brain barrier than the others.
That was a useful first clue, but mice are not people. So the researchers turned to human cells.
How did APOE2 change human pericytes in the lab?
The team started with human stem cells and used the gene-editing tool CRISPR to create three versions that were identical except for their APOE gene. They then grew those stem cells into pericytes.
In a lab model of the blood-brain barrier, built from several brain cell types, pericytes with APOE2 produced the strongest barrier. They also resisted senescence, a kind of cellular aging in which cells stop dividing and stop working properly, and they built up less amyloid-beta, the protein that forms plaques in Alzheimer’s disease.
Why did fat processing in APOE2 cells turn out to matter?
When the researchers analyzed the proteins and fats inside the cells, a pattern stood out. APOE2 pericytes had a different fat profile and fewer lipid droplets, small blobs of stored fat inside the cell. They also made more of the proteins involved in breaking down fats, burning them for energy and moving them around.
In short, APOE2 cells appeared to process fat more efficiently. The most striking result came next: treating APOE3 and APOE4 pericytes with APOE2 protein restored their function and reduced their fat build-up.
What can’t lab-grown cells tell us about Alzheimer’s?
This study shows how APOE2 affects pericytes in mice and in a dish. It does not show that these effects explain why people with APOE2 have lower Alzheimer’s risk, and it did not test any treatment in animals or people.
Cells in a lab lack most of the complexity of a living brain, and effects that look strong there often weaken or disappear in real bodies. Adding APOE2 protein to cells is a long way from a medicine that could safely reach the brain.
What does the APOE2 finding mean for people?
There is nothing to act on yet. You cannot change which APOE version you inherited, and knowing it does not tell you whether you will develop Alzheimer’s. MedlinePlus describes Alzheimer’s disease as the most common form of dementia among older people.
What the study offers is a clearer idea of how a protective gene might work. If helping brain blood vessel cells handle fat better turns out to protect the brain, the authors suggest that could guide new therapies for people at risk of neurodegenerative diseases.
People also ask
What did the study find?
APOE2 mice showed increased pericyte markers and enhanced blood-brain barrier integrity. In a human lab model, APOE2 pericytes provided greater barrier integrity, resisted senescence and accumulated less amyloid-beta. They showed lower lipid droplet accumulation and more proteins for lipid breakdown and transport, and recombinant APOE2 treatment rescued pericyte function in APOE3 and APOE4 pericytes.
What is APOE?
A gene that makes a protein involved in carrying fats, including cholesterol, around the body. Its three main versions are called e2, e3 and e4.
What are pericytes?
Cells that wrap around the brain's smallest blood vessels. They help maintain the blood-brain barrier, which controls what passes from the blood into brain tissue.
Can I find out which APOE version I have?
Genetic testing can show it, but knowing your APOE version does not diagnose or rule out Alzheimer's disease. Anyone considering testing should discuss it with a doctor or genetic counselor.
Could APOE2 become a treatment?
The authors suggest the findings could guide future therapies. Adding APOE2 protein helped cells in a dish, but that is a long way from a treatment for people.
Does this change anything I should do now?
No. Genes cannot be changed, and no treatment based on this work exists. This is general information rather than medical advice.