Extracellular vesicle mitochondrial DNA levels are associated with race and mitochondrial DNA haplogroup

Enhanced mitochondrial function and delivery from adipose-derived stem cell spheres via the EZH2-H3K27me3-PPARγ pathway for advanced therapy

BACKGROUND

Microenvironmental alterations induce significant genetic and epigenetic changes in stem cells. Mitochondria, essential for regenerative capabilities, provide the necessary energy for stem cell function. However, the specific roles of histone modifications and mitochondrial dynamics in human adipose-derived stem cells (ASCs) during morphological transformations remain poorly understood. In this study, we aim to elucidate the mechanisms by which ASC sphere formation enhances mitochondrial function, delivery, and rescue efficiency.

METHODS

ASCs were cultured on chitosan nano-deposited surfaces to form 3D spheres. Mitochondrial activity and ATP production were assessed using MitoTracker staining, Seahorse XF analysis, and ATP luminescence assays. Single-cell RNA sequencing, followed by Ingenuity Pathway Analysis (IPA), was conducted to uncover key regulatory pathways, which were validated through molecular techniques. Pathway involvement was confirmed using epigenetic inhibitors or PPARγ-modulating drugs. Mitochondrial structural integrity and delivery efficiency were evaluated after isolation.

RESULTS

Chitosan-induced ASC spheres exhibited unique compact mitochondrial morphology, characterized by condensed cristae, enhanced mitochondrial activity, and increased ATP production through oxidative phosphorylation. High expressions of mitochondrial complex I genes and elevated levels of mitochondrial complex proteins were observed without an increase in reactive oxygen species (ROS). Epigenetic modification of H3K27me3 and PPARγ involvement were discovered and confirmed by inhibiting H3K27me3 with the specific EZH2 inhibitor GSK126 and by adding the PPARγ agonist Rosiglitazone (RSG). Isolated mitochondria from ASC spheres showed improved structural stability and delivery efficiency, suppressed the of inflammatory cytokines in LPS- and TNFα-induced inflamed cells, and rescued cells from damage, thereby enhancing function and promoting recovery.

CONCLUSION

Enhancing mitochondrial ATP production via the EZH2-H3K27me3-PPARγ pathway offers an alternative strategy to conventional cell-based therapies. High-functional mitochondria and delivery efficiency show significant potential for regenerative medicine applications.

Cell-free DNA release following psychosocial and physical stress in women and men

Cell-free DNA (cfDNA) is continuously shed by all cells in the body, but the regulation of this process and its physiological functions are still largely unknown. Previous research has demonstrated that both nuclear (cf-nDNA) and mitochondrial (cf-mtDNA) cfDNA levels increase in plasma in response to acute psychosocial and physical stress in males. This study further investigated these findings by testing 31 female participants (16 using oral hormonal contraception and 15 not using oral hormonal contraception), and the results were subsequently compared with those of 16 male participants. In addition, cf-nDNA and cf-mtDNA were comparatively quantified in both plasma and saliva at four time points, 2 min before and 2, 15, and 45 min after stress induction. A novel method was implemented to facilitate the straightforward collection of capillary blood by non-medical personnel for plasma analysis. While cf-mtDNA is readily detectable in body fluids due to its high copy number, the quantification of cf-nDNA is challenging due to its low abundance. To overcome this, a multiplex quantitative polymerase chain reaction (qPCR) protocol targeting L1PA2 elements, which are prevalent in the human genome, was utilized. The analysis indicated significantly elevated levels of cf-nDNA in both plasma and saliva in all participants, irrespective of gender, following psychosocial and physical stress. Conversely, neither plasma nor saliva exhibited a consistent or stress-induced release pattern for cf-mtDNA. CfDNA is a promising biomarker that is consistently released after stress in both men and women and can be detected in both plasma and saliva. However, further research is necessary to elucidate the mechanisms of cfDNA release from specific cells and to understand its biological function in the body.

The detection, biological function, and liquid biopsy application of extracellular vesicle-associated DNA

Cell-derived extracellular vesicles (EVs), which carry diverse biomolecules such as nucleic acids, proteins, metabolites, and lipids reflecting their cell of origin, are released under both physiological and pathological conditions. EVs have been demonstrated to mediate cell-to-cell communication and serve as biomarkers. EV-associated DNA (EV-DNA) comprises genomic and mitochondrial DNA (i.e., gDNA and mtDNA) fragments. Some studies have revealed that EV-DNA can represent the full nuclear genome and mitochondrial genome of parental cells. Furthermore, DNA fragments loaded into EVs are stable and can be transferred to recipient cells to regulate their biological functions. In this review, we summarized and discussed EV-DNA research advances with an emphasis on EV-DNA detection at the population-EV and single-EV levels, gene transfer-associated biological functions, and clinical applications as biomarkers for disease liquid biopsy. We hope that this review will provide potential directions or guidance for future EV-DNA investigations.

Neuroinflammatory responses and blood-brain barrier injury in chronic alcohol exposure: role of purinergic P2 × 7 Receptor signaling

Alcohol consumption leads to neuroinflammation and blood‒brain barrier (BBB) damage, resulting in neurological impairment. We previously demonstrated that ethanol-induced disruption of barrier function in human brain endothelial cells was associated with mitochondrial injury, increased ATP and extracellular vesicle (EV) release, and purinergic receptor P2 × 7R activation. Therefore, we aimed to evaluate the effect of P2 × 7R blockade on peripheral and neuro-inflammation in ethanol-exposed mice. In a chronic intermittent ethanol (CIE)-exposed mouse model, P2 × 7R was inhibited by two different methods: Brilliant Blue G (BBG) or gene knockout. We assessed blood ethanol concentration (BEC), brain microvessel gene expression by using RT2 PCR array, plasma P2 × 7R and P-gp, serum ATP, EV-ATP, number of EVs, and EV mtDNA copy numbers. An RT2 PCR array of brain microvessels revealed significant upregulation of proinflammatory genes involved in apoptosis, vasodilation, and platelet activation in CIE-exposed wild-type animals, which were decreased 15-50-fold in BBG-treated-CIE-exposed animals. Plasma P-gp levels and serum P2 × 7R shedding were significantly increased in CIE-exposed animals. Pharmacological or genetic suppression of P2 × 7R decreased receptor shedding to levels equivalent to those in control group. The increase in EV number and EV-ATP content in the CIE-exposed mice was significantly reduced by P2 × 7R inhibition. CIE mice showed augmented EV-mtDNA copy numbers which were reduced in EVs after P2 × 7R inhibition or receptor knockout. These observations suggested that P2 × 7R signaling plays a critical role in ethanol-induced brain injury. Increased extracellular ATP, EV-ATP, EV numbers, and EV-mtDNA copy numbers highlight a new mechanism of brain injury during alcohol exposure via P2 × 7R and biomarkers of such damage. In this study, for the first time, we report the in vivo involvement of P2 × 7R signaling in CIE-induced brain injury.

Neuroinflammatory Responses and Blood-Brain Barrier Injury in Chronic Alcohol Exposure: Role of Purinergic P2X7 Receptor Signaling

Alcohol consumption leads to neuroinflammation and blood-brain barrier (BBB) damage, resulting in neurological impairment. We previously demonstrated that ethanol-induced disruption of barrier function in human brain endothelial cells was associated with mitochondrial injury, increased ATP and extracellular vesicle (EV) release, and purinergic receptor P2X7R activation. Therefore, we aimed to evaluate the effect of P2X7r blockade on peripheral and neuro-inflammation in EtOH-exposed mice. In a chronic intermittent ethanol (CIE)-exposed mouse model, P2X7R was inhibited by two different methods: Brilliant Blue G (BBG) or gene knockout. We assessed blood ethanol concentration (BEC), plasma P2X7R and P-gp, number of extra-cellular vesicles (EV), serum ATP and EV-ATP levels. Brain microvessel gene expression and EV mtDNA copy numbers were measured by RT2 PCR array and digital PCR, respectively. A RT2 PCR array of brain microvessels revealed significant upregulation of proinflammatory genes involved in apoptosis, vasodilation, and platelet activation in CIE-exposed animals, which were decreased 15-50-fold in BBG-treated CIE-exposed animals. Plasma P-gp levels and serum P2X7R shedding were significantly increased in CIE-exposed animals. Pharmacological or genetic suppression of P2X7R decreased P2X7R shedding to levels equivalent to those in control group. The increase in EV number and EV-ATP content in the CIE-exposed mice was significantly reduced by P2X7R inhibition. CIE mice showed augmented EV-mtDNA copy numbers which were reduced in EVs after P2X7R inhibition or receptor knockout. These observations suggested that P2X7R signaling plays a critical role in ethanol-induced brain injury. Increased eATP, EV-ATP, EV numbers, and EV-mtDNA copy numbers highlight a new mechanism of brain injury during alcohol exposure via P2X7R and biomarkers of such damage. In this study, for the first time, we report the in vivo involvement of P2X7R signaling in CIE-induced brain injury.