mitochondrion

Overview

The mitochondrion (plural: mitochondria) is a double-membrane-bound organelle found in the cytoplasm of virtually all eukaryotic cells, widely recognized as the primary site of cellular energy production. Through the process of oxidative phosphorylation (OXPHOS), mitochondria convert nutrients into adenosine triphosphate (ATP), the universal energy currency of the cell. Beyond energy metabolism, mitochondria serve as central regulators of redox homeostasis, calcium signaling, programmed cell death (apoptosis), and cellular senescence. Their outer membrane contains specialized transmembrane β-barrel proteins that function as molecular gatekeepers, a structural feature shared with the outer membranes of Gram-negative bacteria and chloroplasts — a reflection of their endosymbiotic evolutionary origin. Critically, mitochondria harbor their own genome (mitochondrial DNA, or mtDNA), a circular chromosome encoding essential components of the respiratory chain, which is maintained under strict nuclear control and exists in multiple copies per cell, giving rise to phenomena such as heteroplasmy.

Mitochondria are now understood to be far more than static powerhouses. They form dynamic networks that undergo continuous fusion and fission, communicate with other organelles including the endoplasmic reticulum and lysosomes, and can even transfer between cells via tunneling nanotubes, extracellular vesicles, and as free organelles. Disruption of these functions — through oxidative stress, epigenetic dysregulation, impaired mitophagy, or mtDNA mutation — underlies a broad spectrum of human disease, including cardiovascular disease, neurodegeneration, cancer, chronic renal insufficiency, and age-related disorders. This central pathophysiological role has made mitochondria one of the most intensively studied targets in modern biomedical research and drug delivery science.

Focus of Latest Publications

Recent publications have continued to position the mitochondrion as a central therapeutic target in diverse disease settings, especially where metabolic reprogramming, oxidative stress, and cell death pathways are involved. In osteoarthritis, semaglutide was reported to improve mitochondrial metabolic disorders in muscle tissue in mice, with multi-omics analyses indicating that it targeted muscle mitochondria to regulate glutamine metabolism. The study further showed that mitochondria from semaglutide-stimulated C2C12 cells alleviated pain and cartilage damage, apparently by inhibiting muscle glutaminase activity and increasing circulating glutamine, which in turn reduced chondrocyte inflammation. This work highlights a muscle–cartilage axis in which mitochondrial regulation influences joint disease.

Several recent studies also used mitochondria as a focal site for nanomedicine-based interventions. In colitis, a ROS-responsive β-elemene nanoemulsion was shown to aggregate at mitochondrial sites in inflammatory macrophages, where it disrupted the electron transport chain, suppressed oxidative phosphorylation, and reprogrammed energy metabolism, leading to reduced M1 polarization and lower pro-inflammatory cytokine secretion. In cancer therapy, multiple approaches aimed to intensify mitochondrial stress: a glutathione-depleting nanodrug combined mitochondria-targeting photodynamic therapy with cuproptosis to induce mitochondrial dysfunction, immunogenic cell death, and immune activation; another DNA logic circuit-equipped redox amplifier formed DNA aggregates on mitochondria to disrupt membrane potential, increase ROS, and promote ferroptosis and cuproptosis; and a near-infrared-gated nanogenerator delivered nitric oxide and phototherapy to generate ROS/RNS that targeted mitochondria, causing membrane depolarization and ATP depletion.

Mitochondrial dysfunction was also a recurring theme in neurodegenerative disease research. In Alzheimer’s disease, near-infrared carbon dots were reported to selectively target mitochondria and preserve membrane potential under Beta amyloid- and copper(2+)-related oxidative challenge, while also suppressing Beta amyloid aggregation and scavenging reactive oxygen species. In Parkinson’s disease-related work, alpha-synuclein fibrils were found to damage mitochondrial cristae and enhance budding of mitochondrial-derived vesicles, suggesting a link between Synuclein alpha aggregation and mitochondrial quality-control responses. A separate proteomics and network analysis study in Alzheimer’s disease found that mitochondria protein modules were decreased in asymptomatic and symptomatic cases compared with controls, supporting broader mitochondrial involvement in disease progression.

Beyond disease-specific targeting, several studies focused on restoring or transferring mitochondrial function. In ischemic stroke, mitochondrial transcellular transfer through tunneling nanotubes, gap junctions, and extracellular vesicles was described as a mechanism that can reduce oxidative stress, improve neuronal energy metabolism, regulate neuroinflammation, and promote repair after cerebral ischemia-reperfusion injury. In kidney disease, mitochondrial transplantation was reviewed as a strategy to deliver viable, respiratory-competent mitochondria to injured tissue, with preclinical studies showing improved kidney function, reduced inflammation, and preserved mitochondrial structure. Related regenerative approaches also appeared in stroke therapy, where a piezocatalytic hydrogel was reported to target and repair mitochondria after ultrasound activation, suppress anaerobic metabolism, and reduce ischemic neurological dysfunction.