Brain extracellular vesicles from Alzheimer’s Disease and Down Syndrome patients mediate spread of senescence‐like phenotype in vitro
Tina Bilousova, Mikhail Melnik, Yuriko Matsuo, Achyutha Kodavatikanti, Nina Knitowski, Swetha Atluri, Karen H Gylys- Psychiatry and Mental health
- Cellular and Molecular Neuroscience
- Geriatrics and Gerontology
- Neurology (clinical)
- Developmental Neuroscience
- Health Policy
- Epidemiology
Abstract
Background
Alzheimer’s disease (AD) is the prevalent cause of dementia in older adults. Down Syndrome (DS) is the most common chromosomal disorder with strong predisposition to the development of AD. Cellular senescence contributes in the pathophysiology of both AD and DS but the mechanisms are unclear. Senescence associated secretory phenotype (SASP), which refers to a complex of secreted mediators, including soluble factors and extracellular vesicles (EVs) may contribute to the spread of senescence to bystander cells but its role in neurodegenerative disorders has not been evaluated.
Method
Parietal cortex tissue from patients with AD, DS, and normal/low‐pathology (NL) cases was obtained from the UC Irvine ADRC. The cryopreserved human tissue was used for small EV isolation by ultracentrifugation and size exclusive chromatography (SEC). Purity of the EV fractions was confirmed by immunoblotting against positive (CD63, CD9, Syntenin‐1) and negative (calnexin and GM130) EV/exosomal markers, transmission electron microscopy, and nanoparticle tracking analysis. Cell‐type specific EV fractions were isolated by immunoprecipitation (IP). Senescence transfer potential of brain‐derived EVs were assessed in neuroblastoma and glioma cells using senescence associate beta‐galactosidase activity assay, and confirmed by other senescence markers.
Result
Our preliminary data demonstrated the ability of AD and DS, but not NL samples, to transfer senescence to neuroblastoma SH‐SY5Y and glioma U87‐MG cells. Senescence associate beta‐galactosidase activity was on average around 15% higher in cells treated with AD brain derived EVs (AD‐EVs) compared to NL brain EVs (NL‐EVs). This data correlates with around 20% elevation in p21 expression in AD‐EV treated cells. When senescence transfer potentials were compared between AD‐EVs and DS brain derived EVs (DS‐EVs), DS‐EVs exceeded AD‐EVs in their ability to transfer senescence‐like phenotype with around 40% increase in senescence associate beta‐galactosidase activity in cells treated with DS‐EVs. We are currently evaluating levels of senescence‐associated and SASP markers in AD and DS cells and cell‐type specific brain derived small EVs.
Conclusion
We demonstrated an ability of AD and DS brain derived EVs to transfer senescence‐like phenotype in vitro. This phenomenon deserves further investigation to estimate its impact on the progression of AD in Down and non‐Down population along with evaluation its therapeutic potential.