Prolonged treatment with low doses of MitoQ has a protective effect, particularly on VSMCs from AAA, without affecting healthy aortic VSMCs, confirming the cytoprotective potential of MitoQ to limit oxidative stress in AAA-SMC.
Key Findings
Results
NRF2 and KEAP1 protein levels were significantly reduced in the aortic wall of patients with AAA compared to healthy tissue, accompanied by increased oxidative DNA damage markers.
Reduced NRF2 and KEAP1 levels were detected in aortic wall tissue extracts from AAA patients.
Increased 8-OHdG levels were observed in AAA aortic wall tissue, indicating elevated oxidative DNA damage.
These findings indicate defects in the response to oxidative stress in the AAA aortic wall.
This pattern was observed in tissue-level protein analysis.
Results
Relative NRF2 mRNA expression in tissue extracts and VSMC-enriched areas was higher in patients with AAA than in healthy aortic tissue, contrasting with the protein-level findings.
NRF2 expression at the mRNA level was elevated in AAA tissue compared to healthy aortic tissue.
This was observed both in bulk tissue extracts and in VSMC-enriched areas.
The discordance between mRNA upregulation and protein downregulation suggests post-transcriptional or post-translational dysregulation in AAA.
This finding highlights a disconnect between gene expression and protein levels in AAA tissue.
Results
Baseline NRF2 protein levels were significantly higher in AAA-derived SMC and immortalized HAoSMC (iHAoSMC) than in VSMC from healthy aorta in vitro.
In vitro comparison included AAA-SMC, healthy aortic VSMC, and immortalized VSMC (iHAoSMC).
Despite higher baseline NRF2 protein levels in AAA-SMC and iHAoSMC, NRF2 transcriptional activity did not differ significantly between AAA-derived and healthy VSMC at baseline.
This suggests that elevated NRF2 protein in AAA-SMC does not translate directly to increased NRF2 pathway activity under basal conditions.
Results
AAA-derived SMC were less vulnerable to toxic concentrations of MitoQ than healthy VSMC, and cell viability responses to H2O2 differed between cell types.
Cell viability assays showed differential sensitivity to toxic MitoQ doses among the three VSMC populations.
Healthy VSMC exhibited greater vulnerability to high MitoQ concentrations compared to AAA-SMC.
H2O2-induced changes in cell viability were also differentially affected depending on cell origin.
These differences underscore the distinct biological properties of VSMCs derived from aneurysmal versus healthy tissue.
Results
Acute oxidative stress induced by H2O2 increased NRF2 activity in AAA-SMC and iHAoSMC, but not in healthy VSMC.
H2O2 treatment was used to model acute oxidative stress in vitro.
NRF2 transcriptional activity was upregulated in response to H2O2 in AAA-SMC and iHAoSMC.
Healthy VSMC did not show a significant NRF2 activity increase in response to acute H2O2 treatment.
This suggests a differential capacity for NRF2-mediated stress response activation between AAA and healthy VSMCs.
Results
Seven-day pre-treatment with 10 nM MitoQ significantly increased NRF2 activity in AAA-SMC and iHAoSMC, but not in healthy VSMC.
Cells were pre-treated for 7 days with a low dose of 10 nM MitoQ.
NRF2 transcriptional activity was significantly elevated in AAA-SMC and iHAoSMC following MitoQ pre-treatment.
Healthy VSMC did not show significant changes in NRF2 activity after MitoQ pre-treatment.
The selective effect on AAA-SMC and iHAoSMC suggests cell-type-specific responsiveness to MitoQ.
Results
Low-dose MitoQ pre-treatment resulted in a significant reduction of ROS production, particularly in AAA-derived SMC.
Reactive oxygen species (ROS) levels were measured following 7-day 10 nM MitoQ pre-treatment.
The reduction in ROS production was most pronounced in AAA-derived SMC compared to other cell types.
This antioxidant effect occurred alongside the increases in NRF2 activity in AAA-SMC and iHAoSMC.
The selective ROS reduction in AAA-SMC supports the cytoprotective potential of MitoQ specifically in aneurysmal tissue.
Discussion
Immortalized VSMC (iHAoSMC) can serve as a model for investigating oxidative stress responses in AAA-SMC, though they do not react in exactly the same way.
iHAoSMC shared key responses with AAA-SMC, including elevated baseline NRF2 protein, increased NRF2 activity after H2O2 and MitoQ treatment, and reduced ROS after MitoQ.
Despite these similarities, iHAoSMC responses were not identical to those of primary AAA-SMC in all parameters.
The authors conclude immortalized cells are a useful but imperfect surrogate model for AAA-SMC oxidative stress research.
What This Means
This research suggests that vascular smooth muscle cells (VSMCs) lining the walls of abdominal aortic aneurysms (AAA) — dangerous bulges in the main artery of the abdomen — behave very differently from healthy aortic smooth muscle cells when it comes to handling oxidative stress. The study found that in actual aneurysm tissue, key protective proteins (NRF2 and KEAP1) were reduced while oxidative DNA damage was elevated, pointing to a compromised stress defense system. Interestingly, at the gene level, NRF2 was expressed more in aneurysm tissue than healthy tissue, suggesting the cells are trying but failing to mount an adequate protective response.
When the researchers treated cells with MitoQ — a mitochondria-targeted antioxidant supplement — for seven days at a very low dose (10 nM), they found it selectively boosted the NRF2 protective pathway and reduced harmful reactive oxygen species (ROS) specifically in the aneurysm-derived cells. Healthy aortic smooth muscle cells were largely unaffected by the same treatment, suggesting MitoQ acts preferentially where protection is most needed. AAA cells were also found to be more resistant to toxic doses of MitoQ than healthy cells, further highlighting the distinct biology of aneurysmal tissue.
This research suggests MitoQ may hold promise as a targeted therapy to reduce oxidative damage in AAA without harming healthy vascular tissue, which is a significant consideration since current treatment for AAA is largely limited to surgical intervention. The study also found that commercially available immortalized smooth muscle cells can serve as a reasonable — though not perfect — laboratory model for studying aneurysm-related oxidative stress, which has practical implications for future AAA research.
Haas S, Hou B, Peters A, Hatzl J, Böckler D, Dihlmann S. (2026). MitoQ Has Diverse Effects on H2O2-Induced Oxidative Stress and the NRF2 Signalling Pathway in Aortic Smooth Muscle Cells of Different Origins.. Cells. https://doi.org/10.3390/cells15161499