Plasma-derived extracellular vesicles as potential biomarkers and mediators of functional alterations in MELAS

Souza, T.; Klassen, N.; Obi, P.; Ozerklig, B.; Tiede, T.; Srivastava, A.; Pascoe, C.; Marin, S.; Dhingra, S.; Rockman-Greenberg, C.; Saleem, A.

doi:10.64898/2026.06.12.731704

bioRxiv · 10.64898/2026.06.12.731704

Plasma-derived extracellular vesicles as potential biomarkers and mediators of functional alterations in MELAS

Souza, T.·Klassen, N.·Obi, P.·Ozerklig, B.·Tiede, T.·Srivastava, A.·Pascoe, C.·Marin, S.·Dhingra, S.·Rockman-Greenberg, C.·Saleem, A.

View original source ↗Export metadata ↓

Abstract

Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is a genetic disorder characterized by progressive neuromuscular and multisystem symptoms. MELAS typically manifests during childhood, can be difficult to diagnose, and has no cure. Extracellular vesicles (EVs) are lipid-enclosed nanoparticles secreted from cells that contain biological cargo and have demonstrated potential as biomarkers. We investigated the potential of plasma-derived EVs as diagnostic biomarkers of MELAS and examined their functional effects on mitochondrial respiration in treated skeletal muscle myotubes. Plasma-derived EVs were isolated from MELAS patients and age- and sex-matched control individuals, and biophysical characteristics and cargo of EVs analyzed. A Mito Stress Test was performed to assess oxygen consumption rate (OCR) in healthy myotubes treated with Control- or MELAS-EVs to determine the functional effects of circulatory EVs. Nine MELAS patients from two families were studied, and the results were categorized by age, sex and mtDNA heteroplasmy level. EV size and zeta potential remained unchanged. However, total EV concentration was higher in MELAS patients, particularly for small-EVs (<200 nm) and in younger patients (<25 years old). Relative protein yield per EV was lower in the MELAS group, especially among female and younger individuals. EV double-stranded DNA (dsDNA) concentration did not differ between MELAS- and Control-EVs overall, but was higher in male MELAS patients. Protein markers typically enriched in small-EVs showed altered expression in MELAS EVs: TSG101 and CD63 were lower, while flotillin-1 was higher compared to Control-EVs. A decrease in basal OCR was shown in cells treated with MELAS-EVs, with a similar response noted in the group treated with EVs from female MELAS patients. Post-treatment analysis showed no differences in oxidative phosphorylation (OXPHOS) subunit levels between cells treated with MELAS- and Control-EVs. In conclusion, plasma-derived EVs show promise as potential biomarkers for MELAS, and circulating EVs in this patient population may contribute to systemic metabolic dysfunction.

Explore related subjects

Cell Biology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Souza, T., Klassen, N., Obi, P., Ozerklig, B., Tiede, T., Srivastava, A., Pascoe, C., Marin, S., Dhingra, S., Rockman-Greenberg, C., Saleem, A.. 2026-06-15. Plasma-derived extracellular vesicles as potential biomarkers and mediators of functional alterations in MELAS. https://doi.org/10.64898/2026.06.12.731704

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Senescence targeting re-enables injury-responsive repair in a human RPE aging model

Aging is associated with progressive tissue dysfunction and impaired repair after injury. In the retinal pigment epithelium (RPE), these changes contribute to age-related macular degeneration (AMD), yet the mechanisms limiting repair remain incompletely understood. Here, we establish a longitudinal human embryonic stem cell (hESC)-derived RPE aging model that recapitulates key features of aged human donor RPE and combine it with mosaic cell ablation to assess injury-responsive repair. Although aged RPE cells initiate DNA synthesis after injury, they exhibit impaired mitotic progression, uncoupling S-phase entry from epithelial repopulation. Transcriptomic profiling links this defect to a senescence-associated program marked by inflammatory signaling and suppressed mitotic networks. Pharmacologic reduction of senescent cells with Navitoclax shifts aged RPE toward a younger transcriptional profile but does not induce repopulation by itself. Instead, senolytic treatment primes aged RPE for repair, improving epithelial density and homeostatic function only in response to injury, a strategy we term "senolytic priming." These findings establish a human stem-cell-derived platform for investigating age-associated epithelial repair failure and show that aged human RPE retains latent repair capacity that can be re-enabled by targeting cellular senescence.

Cell Biology↗

bioRxiv2026

Bidirectional modulation of aging-associated cellular phenotypes by mitochondrial genome replacement

Mitochondrial dysfunction is a hallmark of cellular aging, but whether age-associated cellular decline can be functionally reversed remains unclear. Here, we applied mitochondrial genome replacement to replicative senescent fibroblasts and aged T cells derived from mice and humans. In senescent fibroblasts, replacement with mitochondria from young cells extended proliferative lifespan, whereas replacement with aged mitochondria accelerated proliferative decline, indicating bidirectional modulation of aging-associated phenotypes. In aged mouse T cells, mitochondrial genome replacement restored proliferative capacity and significantly enhanced antitumor activity following adoptive transfer into tumor-bearing mice. Similarly, mitochondrial genome replacement in aged human T cells enhanced cytokine production and shifted the transcriptomic programs toward a more youthful state. Collectively, these findings identify mitochondrial genetic integrity as a functional regulator of aging-associated cellular states and support the emerging view that mitochondria actively influence cellular aging trajectories.

Cell Biology↗

bioRxiv2026

The MIRO1-BAX Complex Dictates Life and Death at the Mitochondrial Gate

BAX macropores in the outer mitochondrial membrane (OMM) are canonical mediators of apoptosis, but whether the same pore structure can drive distinct cell death pathways remains unclear. Here, we identify the OMM protein MIRO1 as a context-specific modulator of BAX activity. Mechanistically, MIRO1 binds BAX via MIRO1s N-terminal domain to promote macropore formation and the release of mitochondrial DNA (mtDNA) into the cytoplasm, triggering the STING-pIRF3 signaling axis. In glioma cells, this pathway sustains GPX4 expression via pIRF3-mediated transcriptional activation and confers ferroptosis resistance while bypassing inflammation. By contrast, in Parkinsonian neurons, the MIRO1-BAX complex promotes mitochondrial-stress-induced apoptosis. Using structure-guided drug discovery, we developed first-in-class small molecules that allosterically disrupt the MIRO1-BAX complex by engaging MIRO1s distal GTPase pocket. These compounds sensitize glioma cells to ferroptosis and protect neurons from apoptosis. Our findings reveal a disease-specific mitochondrial switch for life-death decisions and illuminate the molecular logic by which cells exploit and interpret OMM permeabilization.

Cell Biology↗