Mitochondrial drug delivery systems for macromolecule and their therapeutic application to mitochondrial diseases

Mitochondrial endogenous substance transport-inspired nanomaterials for mitochondria-targeted gene delivery

Mitochondrial genome (mtDNA) independent of nuclear gene is a set of double-stranded circular DNA that encodes 13 proteins, 2 ribosomal RNAs and 22 mitochondrial transfer RNAs, all of which play vital roles in functions as well as behaviors of mitochondria. Mutations in mtDNA result in various mitochondrial disorders without available cures. However, the manipulation of mtDNA via the mitochondria-targeted gene delivery faces formidable barriers, particularly owing to the mitochondrial double membrane. Given the fact that there are various transport channels on the mitochondrial membrane used to transfer a variety of endogenous substances to maintain the normal functions of mitochondria, mitochondrial endogenous substance transport-inspired nanomaterials have been proposed for mitochondria-targeted gene delivery. In this review, we summarize mitochondria-targeted gene delivery systems based on different mitochondrial endogenous substance transport pathways. These are categorized into mitochondrial steroid hormones import pathways-inspired nanomaterials, protein import pathways-inspired nanomaterials and other mitochondria-targeted gene delivery nanomaterials. We also review the applications and challenges involved in current mitochondrial gene editing systems. This review delves into the approaches of mitochondria-targeted gene delivery, providing details on the design of mitochondria-targeted delivery systems and the limitations regarding the various technologies. Despite the progress in this field is currently slow, the ongoing exploration of mitochondrial endogenous substance transport and mitochondrial biological phenomena may act as a crucial breakthrough in the targeted delivery of gene into mitochondria and even the manipulation of mtDNA.

Revolutionizing cellular energy: The convergence of mitochondrial dynamics and delivery technologies

The intersection of mitochondrial dynamics and delivery technologies heralds a paradigm shift in cellular biology and therapeutic intervention. Mitochondrial dynamics, encompassing fusion, fission, transport, and mitophagy, are critical for cellular energy production, signaling, and homeostasis. Dysregulation of these processes is implicated in a myriad of diseases, including neurodegenerative disorders, cardiovascular diseases, and cancer. Concurrently, advances in delivery technologies, such as nanocarriers, targeted delivery systems, and gene editing tools, offer unprecedented opportunities to manipulate mitochondrial function directly. This review synthesizes current knowledge on mitochondrial dynamics, examines recent breakthroughs in targeted delivery methods, and explores their potential convergence to modulate cellular energetics for therapeutic purposes. By integrating insights from biology, chemistry, and bioengineering, this review highlights the innovative approaches being developed to enhance mitochondrial function, underscoring the potential of this convergence to address complex diseases. This interdisciplinary perspective not only broadens our understanding of cellular processes but also paves the way for novel therapeutic strategies, marking a significant step forward in the quest for precision medicine and targeted interventions in mitochondrial-related diseases.

Mitochondria-targeted BODIPY dyes for small molecule recognition, bio-imaging and photodynamic therapy

Mitochondria are essential for a diverse array of biological functions. There is increasing research focus on developing efficient tools for mitochondria-targeted detection and treatment. BODIPY dyes, known for their structural versatility and excellent spectroscopic properties, are being actively explored in this context. Numerous studies have focused on developing innovative BODIPYs that utilize optical signals for imaging mitochondria. This review presents a comprehensive overview of the progress made in this field, aiming to investigate mitochondria-related biological events. It covers key factors such as design strategies, spectroscopic properties, and cytotoxicity, as well as mechanism to facilitate their future application in organelle imaging and targeted therapy. This work is anticipated to provide valuable insights for guiding future development and facilitating further investigation into mitochondria-related biological sensing and phototherapy.

Photodynamic Therapy Induced Mitochondrial Targeting Strategies for Cancer Treatment: Emerging Trends and Insights

The perpetuity of cancer prevalence at a global level calls for development of novel therapeutic approaches with improved targetability and reduced adverse effects. Conventional cancer treatments have a multitude of limitations such as nonselectivity, invasive nature, and severe adverse effects. Chemotherapy is also losing its efficacy because of the development of multidrug resistance in the majority of cancers. To address these issues, selective targeting-based approaches are being explored for an effective cancer treatment. Mitochondria, being the moderator of a majority of crucial cellular pathways like metabolism, apoptosis, and reactive oxygen species (ROS) homeostasis, are an effective targeting site. Mitochondria-targeted photodynamic therapy (PDT) has arisen as a potential approach in this endeavor. By designing photosensitizers (PSs) that preferentially accumulate in the mitochondria, PDT offers a localized technique to induce cytotoxicity in cancer cells. In this review, we intend to explore the crucial principles and challenges associated with mitochondria-targeted PDT, including variability in mitochondrial function, mitochondria-specific PSs, targeted nanocarrier-based monotherapy, and combination therapies. The hurdles faced by this emerging strategy with respect to safety, optimization, clinical translation, and scalability are also discussed. Nonetheless, mitochondria-targeted PDT exhibits a significant capacity in cancer treatment, especially in combination with other therapeutic modalities. With perpetual research and technological advancements, this treatment strategy is a great addition to the arsenal of cancer treatment options, providing better tumor targetability while reducing the damage to surrounding healthy tissues. This review emphasizes the current status of mitochondria-targeted PDT, limitations, and future prospects in its pursuit of safe and efficacious cancer therapy.

Synergistic dual cell therapy for atherosclerosis regression: ROS-responsive Bio-liposomes co-loaded with Geniposide and Emodin

The development of nanomaterials for delivering natural compounds has emerged as a promising approach for atherosclerosis therapy. However, premature drug release remains a challenge. Here, we present a ROS-responsive biomimetic nanocomplex co-loaded with Geniposide (GP) and Emodin (EM) in nanoliposome particles (LP NPs) for targeted atherosclerosis therapy. The nanocomplex, hybridized with the macrophage membrane (Møm), effectively evades immune system clearance and targets atherosclerotic plaques. A modified thioketal (TK) system responds to ROS-rich plaque regions, triggering controlled drug release. In vitro, the nanocomplex inhibits endothelial cell apoptosis and macrophage lipid accumulation, restores endothelial cell function, and promotes cholesterol effluxion. In vivo, it targets ROS-rich atherosclerotic plaques, reducing plaque area ROS levels and restoring endothelial cell function, consequently promoting cholesterol outflow. Our study demonstrates that ROS-responsive biomimetic nanocomplexes co-delivering GP and EM exert a synergistic effect against endothelial cell apoptosis and lipid deposition in macrophages, offering a promising dual-cell therapy modality for atherosclerosis regression.

Exploiting nuclear-mitochondrial cross-talk in theranostics: Enhancing drug delivery and diagnostic precision

The dynamic interplay between nuclear and mitochondrial processes plays a pivotal role in cellular homeostasis and disease progression. Exploiting this nuclear-mitochondrial cross-talk has emerged as a promising avenue in the field of theranostics, offering enhanced drug delivery and diagnostic precision for a wide range of medical conditions, particularly cancer. This abstract provides a brief overview of the key concepts and recent advancements in this rapidly evolving field. Recent research has elucidated the significance of mitochondrial dysfunction in various diseases, including cancer. Mitochondria, often referred to as the "powerhouses" of the cell, not only regulate energy production but also contribute to critical processes such as apoptosis, ROS generation, and metabolic signaling. Dysregulation of these mitochondrial functions is frequently associated with disease pathogenesis. In theranostics, the targeted modulation of mitochondrial function holds great promise. Mitochondria-targeted drug delivery systems have been designed to selectively deliver therapeutic agents to these organelles, thereby mitigating mitochondrial dysfunction while minimizing off-target effects. This precise drug delivery enhances the therapeutic efficacy of anticancer drugs and reduces the risk of drug resistance. Moreover, the diagnostic potential of nuclear-mitochondrial cross-talk is being harnessed to develop novel biomarkers and imaging techniques. Mitochondrial DNA mutations and alterations in mitochondrial metabolism serve as valuable indicators of disease progression and drug responsiveness. Non-invasive imaging modalities, such as positron emission tomography (PET) and magnetic resonance imaging (MRI), have been employed to visualize mitochondrial activity and assess therapeutic outcomes.

Engineering metabolism to modulate immunity

Metabolic programming and reprogramming have emerged as pivotal mechanisms for altering immune cell function. Thus, immunometabolism has become an attractive target area for treatment of immune-mediated disorders. Nonetheless, many hurdles to delivering metabolic cues persist. In this review, we consider how biomaterials are poised to transform manipulation of immune cell metabolism through integrated control of metabolic configurations to affect outcomes in autoimmunity, regeneration, transplant, and cancer. We emphasize the features of nanoparticles and other biomaterials that permit delivery of metabolic cues to the intracellular compartment of immune cells, or strategies for altering signals in the extracellular space. We then provide perspectives on the potential for reciprocal regulation of immunometabolism by the physical properties of materials themselves. Lastly, opportunities for clinical translation are highlighted. This discussion contributes to our understanding of immunometabolism, biomaterials-based strategies for altering metabolic configurations in immune cells, and emerging concepts in this evolving field.

Neuroprotective Effects of Probucol against Rotenone-Induced Toxicity via Suppression of Reactive Oxygen Species Production in SH-SY5Y Cells

Probucol is a hyperlipidemic drug with antioxidant properties. It has been reported to prevent mitochondrial dysfunction, reduce oxidative stress, and suppress neurotoxicity in neurodegenerative disease models, including Parkinson's disease models. However, the molecular mechanisms underlying the neuroprotective effects of probucol have been not examined yet. Thus, in this study, we investigated whether probucol can alleviate the effects of a mitochondrial complex I inhibitor, rotenone, on a human neuroblastoma cell line (SH-SY5Y). We evaluated the cell viability and cytotoxicity and apoptosis rates of SH-SY5Y cells treated with rotenone and probucol or edaravone, a known free-radical scavenger. Subsequently, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) levels in the cells were evaluated to determine the effects of probucol on mitochondrial function. We found that rotenone caused cytotoxicity, cell apoptosis, and mitochondrial dysfunction, enhanced ROS generation, and impaired MMP. However, probucol could inhibit this rotenone-induced decrease in cell viability, MMP loss, intracellular ROS generation, and apoptosis. These results suggest that probucol exerts neuroprotective effects via MMP stabilization and the inhibition of ROS generation. Additionally, this effect of probucol was equal to or greater than and more persistent than that of edaravone. Thus, we believe probucol may be a promising drug for the treatment of neurodegenerative diseases, such as Parkinson's and Alzheimer's diseases.

Nanomedicine in cancer therapy

Cancer remains a highly lethal disease in the world. Currently, either conventional cancer therapies or modern immunotherapies are non-tumor-targeted therapeutic approaches that cannot accurately distinguish malignant cells from healthy ones, giving rise to multiple undesired side effects. Recent advances in nanotechnology, accompanied by our growing understanding of cancer biology and nano-bio interactions, have led to the development of a series of nanocarriers, which aim to improve the therapeutic efficacy while reducing off-target toxicity of the encapsulated anticancer agents through tumor tissue-, cell-, or organelle-specific targeting. However, the vast majority of nanocarriers do not possess hierarchical targeting capability, and their therapeutic indices are often compromised by either poor tumor accumulation, inefficient cellular internalization, or inaccurate subcellular localization. This Review outlines current and prospective strategies in the design of tumor tissue-, cell-, and organelle-targeted cancer nanomedicines, and highlights the latest progress in hierarchical targeting technologies that can dynamically integrate these three different stages of static tumor targeting to maximize therapeutic outcomes. Finally, we briefly discuss the current challenges and future opportunities for the clinical translation of cancer nanomedicines.

Enhanced apoptosis and mitochondrial cell death by paclitaxel-loaded TPP-TPGS1000-functionalized nanoemulsion

Background: The present research was designed to develop a nanoemulsion (NE) of triphenylphosphine-D-α-tocopheryl-polyethylene glycol succinate (TPP-TPGS₁₀₀₀) and paclitaxel (PTX) to effectively deliver PTX to improve breast cancer therapy. Materials & methods: A quality-by-design approach was applied for optimization and in vitro and in vivo characterization were performed. Results: The TPP-TPGS₁₀₀₀-PTX-NE enhanced cellular uptake, mitochondrial membrane depolarization and G₂M cell cycle arrest compared with free-PTX treatment. In addition, pharmacokinetics, biodistribution and in vivo live imaging studies in tumor-bearing mice showed that TPP-TPGS₁₀₀₀-PTX-NE had superior performance compared with free-PTX treatment. Histological and survival investigations ascertained the nontoxicity of the nanoformulation, suggesting new opportunities and potential to treat breast cancer. Conclusion: TPP-TPGS₁₀₀₀-PTX-NE improved the efficacy of breast cancer treatment by enhancing its effectiveness and decreasing drug toxicity.

Delivery Systems for Mitochondrial Gene Therapy: A Review

Mitochondria are membrane-bound cellular organelles of high relevance responsible for the chemical energy production used in most of the biochemical reactions of cells. Mitochondria have their own genome, the mitochondrial DNA (mtDNA). Inherited solely from the mother, this genome is quite susceptible to mutations, mainly due to the absence of an effective repair system. Mutations in mtDNA are associated with endocrine, metabolic, neurodegenerative diseases, and even cancer. Currently, therapeutic approaches are based on the administration of a set of drugs to alleviate the symptoms of patients suffering from mitochondrial pathologies. Mitochondrial gene therapy emerges as a promising strategy as it deeply focuses on the cause of mitochondrial disorder. The development of suitable mtDNA-based delivery systems to target and transfect mammalian mitochondria represents an exciting field of research, leading to progress in the challenging task of restoring mitochondria's normal function. This review gathers relevant knowledge on the composition, targeting performance, or release profile of such nanosystems, offering researchers valuable conceptual approaches to follow in their quest for the most suitable vectors to turn mitochondrial gene therapy clinically feasible. Future studies should consider the optimization of mitochondrial genes' encapsulation, targeting ability, and transfection to mitochondria. Expectedly, this effort will bring bright results, contributing to important hallmarks in mitochondrial gene therapy.

Morphological Transformation and In Situ Polymerization of Caspase-3 Responsive Diacetylene-Containing Lipidated Peptide Amphiphile for Self-Amplified Cooperative Antitumor Therapy

In order to artificially regulate cell behaviors, intracellular polymerization as an emerging chemical technique has attracted much attention. Yet, it is still a challenge to achieve effective intracellular polymerization to conquer tumors in the complex cellular environment. Herein, this work develops a tumor-targeting and caspase-3 responsive nanoparticle composed of a diacetylene-containing lipidated peptide amphiphile and mitochondria-targeting photosensitizer (C3), which undergoes nanoparticle-to-nanofiber transformation and efficient in situ polymerization triggered by photodynamic treatment and activation of caspase-3. The locational nanofibers on the mitochondria membranes lead to mitochondrial reactive oxygen species (mtROS) burst and self-amplified circulation, offering persistent high oxidative stress to induce cell apoptosis. This study provides a strategy for greatly enhanced antitumor therapeutic efficacy through mtROS burst and self-amplified circulation induced by intracellular transformation and in situ polymerization.

Muscle Delivery of Mitochondria-Targeted Drugs for the Treatment of Sarcopenia: Rationale and Perspectives

An impairment in mitochondrial homeostasis plays a crucial role in the process of aging and contributes to the incidence of age-related diseases, including sarcopenia, which is defined as an age-dependent loss of muscle mass and strength. Mitochondrial dysfunction exerts a negative impact on several cellular activities, including bioenergetics, metabolism, and apoptosis. In sarcopenia, mitochondria homeostasis is disrupted because of reduced oxidative phosphorylation and ATP generation, the enhanced production of reactive species, and impaired antioxidant defense. This review re-establishes the most recent evidence on mitochondrial defects that are thought to be relevant in the pathogenesis of sarcopenia and that may represent promising therapeutic targets for its prevention/treatment. Furthermore, we describe mechanisms of action and translational potential of promising mitochondria-targeted drug delivery systems, including molecules able to boost the metabolism and bioenergetics, counteract apoptosis, antioxidants to scavenge reactive species and decrease oxidative stress, and target mitophagy. Even though these mitochondria-delivered strategies demonstrate to be promising in preclinical models, their use needs to be promoted for clinical studies. Therefore, there is a compelling demand to further understand the mechanisms modulating mitochondrial homeostasis, to characterize powerful compounds that target muscle mitochondria to prevent sarcopenia in aged people.

Organelle-targeted therapies: a comprehensive review on system design for enabling precision oncology

Cancer is a major threat to human health. Among various treatment methods, precision therapy has received significant attention since the inception, due to its ability to efficiently inhibit tumor growth, while curtailing common shortcomings from conventional cancer treatment, leading towards enhanced survival rates. Particularly, organelle-targeted strategies enable precise accumulation of therapeutic agents in organelles, locally triggering organelle-mediated cell death signals which can greatly reduce the therapeutic threshold dosage and minimize side-effects. In this review, we comprehensively discuss history and recent advances in targeted therapies on organelles, specifically including nucleus, mitochondria, lysosomes and endoplasmic reticulum, while focusing on organelle structures, organelle-mediated cell death signal pathways, and design guidelines of organelle-targeted nanomedicines based on intervention mechanisms. Furthermore, a perspective on future research and clinical opportunities and potential challenges in precision oncology is presented. Through demonstrating recent developments in organelle-targeted therapies, we believe this article can further stimulate broader interests in multidisciplinary research and technology development for enabling advanced organelle-targeted nanomedicines and their corresponding clinic translations.

Mitochondria-targeted alginate/triphenylphosphonium-grafted-chitosan for treatment of hepatocellular carcinoma

Mitochondrial targeting of anticancer drugs can effectively eradicate chemotherapy-refractory cells through different mechanisms. This work presents the rational designing of mitochondria-targeted core–shell polymeric nanoparticles (NPs) for efficient delivery of doxorubicin (DOX) to the hepatic carcinoma mitochondria. DOX was electrostatically nano-complexed with sodium alginate (SAL) then coated with mitotropic triphenylphosphonium-grafted chitosan (TPP⁺-g-CS) nanoshell. Polyvinyl alcohol (PVA) was co-solubilized into the TPP⁺-g-CS solution to enhance the stability of the developed NPs. The optimum NPs formula is composed of TPP⁺-g-CS (0.05% w/v) coating a DOX-SAL core complex (0.05% w/v), with 0.2% PVA relative to CS (w/w). The optimum NPs attained an entrapment efficiency of 63.33 ± 10.18%; exhibited a spherical shape with particle size of 70–110 nm and a positive surface charge which enhances mitochondrial uptake. FTIR and DSC studies results were indicative of an efficacious poly-complexation. In vitro biological experiments proved that the developed mitotropic NPs exhibited a significantly lower IC₅₀, effectively induced apoptotic cell death and cell cycle arrest. Moreover, the in vivo studies demonstrated an enhanced antitumor bioactivity for the mitotropic NPs along with a reduced biological toxicity profile. In conclusion, this study proposes a promising nanocarrier system for the efficient targeting of DOX to the mitochondria of hepatic tumors.

Mitochondrial targeting of anticancer drugs can effectively eradicate tumour cells. TPP⁺-grafted-chitosan based core–shell nanoparticles were successfully internalized into the mitochondria of HCC cells. Also exhibited antiproliferative activity against liver cancer.

Mitochondrial targeting of potent nanoparticulated drugs in combating diseases

Mitochondrial dysfunction, characterized by the electron transport chain (ETC) leakage and reduced adenosine tri-phosphate synthesis, occurs primarily due to free radicals -induced mutations in either the mitochondrial deoxyribonucleic acid (mtDNA) or nuclear (n) DNA caused by pathogenic infections, toxicant exposures, adverse drug-effects, or other environmental exposures, leading to secondary dysfunction affecting ischemic, diabetic, cancerous, and degenerative diseases. In these concerns, mitochondria-targeted remedies may include a significant role in the protection and treatment of mitochondrial function to enhance its activity. Coenzyme Q10 pyridinol and pyrimidinol antioxidant analogues and other potent drug-compounds for their multifunctional radical quencher and other anti-toxic activities may take a significant therapeutic effectivity for ameliorating mitochondrial dysfunction. Moreover, the encapsulation of these bioactive ligands-attached potent compounds in vesicular system may enable them a superb biological effective for the treatment of mitochondria-targeted dysfunction-related diseases with least side effects. This review depicts mainly on mitochondrial enzymatic dysfunction and their amelioration by potent drugs with the usages of nanoparticulated delivery system against mitochondria-affected diseases.

Design and application of DNA nanostructures for organelle-targeted delivery of anticancer drugs

INTRODUCTION

DNA nanostructures targeting organelles are of great significance for the early diagnosis and precise therapy of human cancers. This review is expected to promote the development of DNA nanostructure-based cancer treatment with organelle-level precision in the future.

AREAS COVERED

In this review, we introduce the different principles for targeting organelles, summarize the progresses in the development of organelle-targeting DNA nanostructures, highlight their advantages and applications in disease treatment, and discuss current challenges and future prospects.

EXPERT OPINION

Accurate targeting is a basic problem for effective cancer treatment. However, current DNA nanostructures cannot meet the actual needs. Targeting specific organelles is expected to further improve the therapeutic effect and overcome tumor cell resistance, thereby holding great practical significance for tumor treatment in the clinic. With the deepening of the research on the molecular mechanism of disease development, especially on tumorigenesis and tumor progression, and increasing understanding of the behavior of biological materials in living cells, more versatile DNA nanostructures will be constructed to target subcellular organelles for drug delivery, essentially promoting the early diagnosis of cancers, classification, precise therapy and the estimation of prognosis in the future.

Redox-Based Strategy for Selectively Inducing Energy Crisis Inside Cancer Cells: An Example of Modifying Dietary Curcumin to Target Mitochondria

Reprograming of energy metabolism is a major hallmark of cancer, but its effective intervention is still a challenging task due to metabolic heterogeneity and plasticity of cancer cells. Herein, we report a general redox-based strategy for meeting the challenge. The strategy was exemplified by a dietary curcumin analogue (MitoCur-1) that was designed to target mitochondria (MitoCur-1). By virtue of its electrophilic and mitochondrial-targeting properties, MitoCur-1 generated reactive oxygen species (ROS) more effectively and selectively in HepG2 cells than in L02 cells via the inhibition of mitochondrial antioxidative thioredoxin reductase 2 (TrxR2). The ROS generation preferentially mediated the energy crisis of HepG2 cells in a dual-inhibition fashion against both mitochondrial and glycolytic metabolisms, which could hit the metabolic plasticity of HepG2 cells. The ROS-dependent energy crisis also allowed its preferential killing of HepG2 cells (IC₅₀ = 1.4 μM) over L02 cells (IC₅₀ = 9.1 μM), via induction of cell-cycle arrest, apoptosis and autophagic death, and its high antitumor efficacy in vivo, in nude mice bearing HepG2 tumors (15 mg/kg). These results highlight that inhibiting mitochondrial TrxR2 to produce ROS by electrophiles is a promising redox-based strategy for the effective intervention of cancer cell energy metabolic reprograming.

Folate-Decorated Cross-Linked Cytochrome c Nanoparticles for Active Targeting of Non-Small Cell Lung Carcinoma (NSCLC)

The folate receptor alpha (FR), which is overexpressed in solid tumors including NSCLC, can be utilized for active tumor targeting to afford more effective cancer therapies. In this context, cytochrome c (Cyt c) has drawn attention to cancer research because it is non-toxic, yet, when delivered to the cytoplasm of cancer cells, can kill them by inducing apoptosis. Cyt c nanoparticles (NPs, 169 ± 9 nm) were obtained by solvent precipitation with acetonitrile, and stabilized by reversible homo-bifunctional crosslinking to accomplish a Cyt-c-based drug delivery system that combines stimulus-responsive release and active targeting. Cyt c was released under intracellular redox conditions, due to an S–S bond in the NPs linker, while NPs remained intact without any release under extracellular conditions. The NP surface was decorated with a hydrophilic folic acid–polyethylene glycol (FA–PEG) polymer for active targeting. The FA-decorated NPs specifically recognized and killed cancer cells (IC50 = 47.46 µg/mL) that overexpressed FR, but showed no toxicity against FR-negative cells. Confocal microscopy confirmed the preferential uptake and apoptosis induction of our NPs by FR-positive cancer cells. In vivo experiments using a Lewis lung carcinoma (LLC) mouse model showed visible NP accumulation within the tumor and inhibited the growth of LLC tumors.

Folate-Decorated Cross-Linked Cytochrome c Nanoparticles for Active Targeting of Non-Small Cell Lung Carcinoma (NSCLC)

The folate receptor alpha (FR), which is overexpressed in solid tumors including NSCLC, can be utilized for active tumor targeting to afford more effective cancer therapies. In this context, cytochrome c (Cyt c) has drawn attention to cancer research because it is non-toxic, yet, when delivered to the cytoplasm of cancer cells, can kill them by inducing apoptosis. Cyt c nanoparticles (NPs, 169 ± 9 nm) were obtained by solvent precipitation with acetonitrile, and stabilized by reversible homo-bifunctional crosslinking to accomplish a Cyt-c-based drug delivery system that combines stimulus-responsive release and active targeting. Cyt c was released under intracellular redox conditions, due to an S–S bond in the NPs linker, while NPs remained intact without any release under extracellular conditions. The NP surface was decorated with a hydrophilic folic acid–polyethylene glycol (FA–PEG) polymer for active targeting. The FA-decorated NPs specifically recognized and killed cancer cells (IC50 = 47.46 µg/mL) that overexpressed FR, but showed no toxicity against FR-negative cells. Confocal microscopy confirmed the preferential uptake and apoptosis induction of our NPs by FR-positive cancer cells. In vivo experiments using a Lewis lung carcinoma (LLC) mouse model showed visible NP accumulation within the tumor and inhibited the growth of LLC tumors.

Folate-Decorated Cross-Linked Cytochrome c Nanoparticles for Active Targeting of Non-Small Cell Lung Carcinoma (NSCLC)

The folate receptor alpha (FR), which is overexpressed in solid tumors including NSCLC, can be utilized for active tumor targeting to afford more effective cancer therapies. In this context, cytochrome c (Cyt c) has drawn attention to cancer research because it is non-toxic, yet, when delivered to the cytoplasm of cancer cells, can kill them by inducing apoptosis. Cyt c nanoparticles (NPs, 169 ± 9 nm) were obtained by solvent precipitation with acetonitrile, and stabilized by reversible homo-bifunctional crosslinking to accomplish a Cyt-c-based drug delivery system that combines stimulus-responsive release and active targeting. Cyt c was released under intracellular redox conditions, due to an S–S bond in the NPs linker, while NPs remained intact without any release under extracellular conditions. The NP surface was decorated with a hydrophilic folic acid–polyethylene glycol (FA–PEG) polymer for active targeting. The FA-decorated NPs specifically recognized and killed cancer cells (IC50 = 47.46 µg/mL) that overexpressed FR, but showed no toxicity against FR-negative cells. Confocal microscopy confirmed the preferential uptake and apoptosis induction of our NPs by FR-positive cancer cells. In vivo experiments using a Lewis lung carcinoma (LLC) mouse model showed visible NP accumulation within the tumor and inhibited the growth of LLC tumors.

A multimodal fluorescent probe for portable colorimetric detection of pH and it's application in mitochondrial bioimaging

Mitochondria, as vital energy supplying organelles, play important roles in cellular metabolism, which are closely related with mitochondrial pH (∼8.0). In this work, a novel multimodal fluorescent probe was employed for ratiometric and colorimetric detection of pH. The probe is designed to work by controlling benzothiazole phenol-hemicyanine system as the interaction site and hemicyanine connected by conjugate bonds as the mitochondrial targeting, which also could make the fluorescence of probe red-shifted. This system results in a perfect ratiometric fluorescent response, whose emission changed from red to blue under pH 2.0-10.0, having a broad linear range (pH = 3.0-10.0). And the marked colour change (light yellow to deep purple via naked eye under pH 2.0-11.0) could be used to construct the test strip colorimetry and smartphone APP detection method, realizing the fast, portable, and accurate detection of pH in vitro and environment. Besides, the probe owns the characteristics of easy loading, high selectivity and staining ability of mitochondria, and low cytotoxicity, thereby allowing imaging of pH values and real-time monitor the subcellular mitochondria pH changes caused by drugs in living cells. It thus could be used to monitor the organ-specific dynamics related to transitions between pathological and physiological states.

Rational Designs at the Forefront of Mitochondria-Targeted Gene Delivery: Recent Progress and Future Perspectives

Mitochondria play an essential role in cellular metabolism and generate energy in cells. To support these functions, several proteins are encoded in the mitochondrial DNA (mtDNA). The mutation of mtDNA causes mitochondrial dysfunction and ultimately results in a variety of inherited diseases. To date, gene delivery systems targeting mitochondria have been developed to ameliorate mtDNA mutations. However, applications of these strategies in mitochondrial gene therapy are still being explored and optimized. Thus, from this perspective, we herein highlight recent mitochondria-targeting strategies for gene therapy and discuss future directions for effective mitochondria-targeted gene delivery.

Novel Prodrug Supramolecular Nanoparticles Capable of Rapid Mitochondrial-Targeted and ROS-Responsive for Pancreatic Cancer Therapy

Mitochondrial dysfunction is a feature of cancer cells and targeting cancer mitochondria has emerged as a promising anticancer therapy. In this study, a novel mitochondria-targeted and ROS-responsive drug delivery nanoplatform...

Extracellular Mitochondrial Components and Effects on Cardiovascular Disease

Besides being powerhouses of the cell, mitochondria released into extracellular space act as intercellular signaling. Mitochondria and their components mediate cell-to-cell communication in free form or embedded in a carrier. The pathogenesis of cardiovascular disease is complex, which shows close relationship with inflammation and metabolic abnormalities. Since mitochondria sustain optimal function of the heart, extracellular mitochondria are emerging as a key regulator in the development of cardiovascular disease. In this review, we provide recent findings in the presence and forms of mitochondria transfer between cells, as well as the effects of these mitochondria on vascular inflammation and ischemic myocardium. Mitochondrial transplantation is a novel treatment paradigm for patients suffering from acute cardiovascular accident and challenges the traditional methods of mitochondria isolation.

Synthesis of Triphenylphosphonium Phospholipid Conjugates for the Preparation of Mitochondriotropic Liposomes

Surface modification of liposomes with a ligand is facilitated by the conjugation of the ligand to a hydrophobic molecule that serves to anchor the ligand to the liposomal bilayer. We describe here a simple protocol to conjugate a triphenylphosphonium group to several commercially available functionalized phospholipids. The resulting triphenylphosphonium-conjugated lipids can be used to prepare liposomes that preferentially associate with mitochondria when exposed to live mammalian cells in culture.

Nanotherapeutic approaches to target mitochondria in cancer

Treatment of cancer cells exemplifies a difficult test in the light of challenges associated with the nature of cancer cells and the severe side effects too. After making a large number of trials using both traditional and advanced therapies (immunotherapy and hormone therapy), approaches to design new therapies have reached a saturation level. However, nanotechnology-based approaches exhibit higher efficacy and great potential to bypass many of such therapeutic limitations. Because of their higher target specificity, the use of nanoparticles offers incredible potential in cancer therapeutics. Mitochondria, acting as a factory of energy production in cells, reveal an important role in the death as well as the survival of cells. Because of its significant involvement in the proliferation of cancer cells, it is being regarded as an important target for cancer therapeutics. Numerous studies reveal that nanotechnology-based approaches to directly target the mitochondria may help in improving the survival rate of cancer patients. In the current study, we have detailed the significance of mitochondria in the development of cancer phenotype, as well as indicated it as the potential targets for cancer therapy. Our study further highlights the importance of different nanoparticle-based approaches to target mitochondria of cancer cells and the associated outcomes of different studies. Though, nanotechnology-based approaches to target mitochondria of cancer cells demonstrate a potential and efficient way in cancer therapeutics. Yet, further study is needed to overcome the linked limitations.

Mitochondrial DNA Copy Number and Developmental Origins of Health and Disease (DOHaD)

Mitochondrial dysfunction is known to contribute to mitochondrial diseases, as well as to a variety of aging-based pathologies. Mitochondria have their own genomes (mitochondrial DNA (mtDNA)) and the abnormalities, such as point mutations, deletions, and copy number variations, are involved in mitochondrial dysfunction. In recent years, several epidemiological studies and animal experiments have supported the Developmental Origin of Health and Disease (DOHaD) theory, which states that the environment during fetal life influences the predisposition to disease and the risk of morbidity in adulthood. Mitochondria play a central role in energy production, as well as in various cellular functions, such as apoptosis, lipid metabolism, and calcium metabolism. In terms of the DOHaD theory, mtDNA copy number may be a mediator of health and disease. This paper summarizes the results of recent epidemiological studies on the relationship between environmental factors and mtDNA copy number during pregnancy from the perspective of DOHaD theory. The results of these studies suggest a hypothesis that mtDNA copy number may reflect environmental influences during fetal life and possibly serve as a surrogate marker of health risks in adulthood.

Smart Stimuli-Responsive and Mitochondria Targeting Delivery in Cancer Therapy

Dysfunction in the mitochondria (Mc) contributes to tumor progression. It is a major challenge to deliver therapeutic agents specifically to the Mc for precise treatment. Smart drug delivery systems are based on stimuli-responsiveness and active targeting. Here, we give a whole list of documented pathways to achieve smart stimuli-responsive (St-) and Mc-targeted DDSs (St-Mc-DDSs) by combining St and Mc targeting strategies. We present the formulations, targeting characteristics of St-Mc-DDSs and clarify their anti-cancer mechanisms as well as improvement in efficacy and safety. St-Mc-DDSs usually not only have Mc-targeting groups, molecules (lipophilic cations, peptides, and aptamers) or materials but also sense the surrounding environment and correspondingly respond to internal biostimulators such as pH, redox changes, enzyme and glucose, and/or externally applied triggers such as light, magnet, temperature and ultrasound. St-Mc-DDSs exquisitely control the action site, increase therapeutic efficacy and decrease side effects of the drug. We summarize the clinical research progress and propose suggestions for follow-up research. St-Mc-DDSs may be an innovative and sensitive precision medicine for cancer treatment.

Rh(iii)-Catalysed synthesis of cinnolinium and fluoranthenium salts using C-H activation/annulation reactions: organelle specific mitochondrial staining applications

The construction of a novel class of indazolo[2,1-a]cinnolin-7-ium and diazabenzofluoranthenium salts was developed by using Rh(iii)-catalyzed C-H activation/annulation reactions with 2-phenyl-2H-indazole, and internal alkynes, which resulted in structurally important polycyclic heteroaromatic compounds (PHAs). This reaction uses mild reaction conditions and has a high efficiency, low catalyst loading, and wide substrate scope. The overall catalytic process involves C-H activation followed by C-C/C-N bond formation. Furthermore, the synthesised cinnolinium/fluoranthenium salts exhibit potential fluorescence properties and 5i was targeted in particular for specific mitochondrial staining in order to investigate cancer cell lines.

Progress in tumour-targeted drug delivery based on cell-penetrating peptides

Since the discovery of cell-penetrating peptides (CPP) in the 1980s, they have played a unique role in various fields owing to their excellent and unique cell membrane penetration function. In particular, in the treatment of tumours, CPPS have been used to deliver several types of 'cargos' to cancer cells. To address the insufficient targeting ability, non-selectivity, and blood instability, activatable cell-penetrating peptides, which can achieve targeted drug delivery in tumour treatment, enhance curative effects, and reduce toxicity have been developed. This study reviews the application of different cell-penetrating peptides in tumour-targeted delivery, overcoming multidrug resistance, organelle targeting, tumour imaging, and diagnosis, and summarises the different mechanisms of activatable cell-penetrating peptides in detail.

A near-infrared fluorescent probe based on a hemicyanine dye with an oxazolidine switch for mitochondrial pH detection

A near-infrared fluorescent probe (AH+) has been prepared by incorporating an oxazolidine switch into a near-infrared hemicyanine dye. The probe shows fast and sensitive responses to pH from an oxazolidine switch to the hemicyanine dye upon pH decreases from 10.0 to 5.0. The probe shows good photostability, low cytotoxicity, and reversible fluorescence responses to pH changes with a pKa value of 7.6. It has been successfully used to determine pH changes in mitochondria.

ICT-based fluorescent ratiometric probe for monitoring mitochondrial peroxynitrite in living cells

Mitochondria-targeted near-infrared fluorescent probe for the detection of peroxynitrite and the bioimaging of peroxynitrite in cells.

Targeting the Mitochondrial Genome Via a MITO-Porter : Evaluation of mtDNA and mtRNA Levels and Mitochondrial Function

Genetic mutations and defects in mitochondrial DNA (mtDNA) are associated with certain types of mitochondrial dysfunctions, ultimately resulting in the emergence of a variety of human diseases. To achieve an effective mitochondrial gene therapy, it will be necessary to deliver therapeutic agents to the innermost mitochondrial space (the mitochondrial matrix), which contains the mtDNA pool. We recently developed a MITO-Porter, a liposome-based nanocarrier that delivers cargo to mitochondria via a membrane-fusion mechanism. In this chapter, we discuss the methodology used to deliver bioactive molecules to the mitochondrial matrix using a Dual Function (DF)-MITO-Porter, a liposome-based nanocarrier that delivers it cargo by means of a stepwise process, and an evaluation of mtDNA levels and mitochondrial activities in living cells. We also discuss mitochondrial gene silencing by the mitochondrial delivery of antisense RNA oligonucleotide (ASO) targeting mtDNA-encoded mRNA using the MITO-Porter system.

Portfolio Targeting Strategy To Realize the Assembly and Membrane Fusion-Mediated Delivery of Gold Nanoparticles to Mitochondria for Enhanced NIR Photothermal Therapies

Targeting mitochondria has always been a challenging goal for therapeutic nanoparticle agents due to their heterotypic features and size, which usually lead to a lysosome/endosome endocytosis pathway. To overcome this limitation, in this work, a portfolio targeting strategy combining a small targeting molecule with a biomembrane was developed. Modification of small targeting molecule H₂N-TPP on gold nanoparticles (GNPs) could not only facilitate the mitochondrial targeting but could also induce gold nanoparticle assembly. Therefore, the GNPs were endowed with good absorption and photothermal conversion abilities in the near-infrared (NIR) region. Meanwhile, a biomimetic strategy was adopted by wrapping the gold nanoparticle assembly (GNA) with cancer cell membranes (CCMs), which helped the GNA enter the prostatic cancer cell via a homotypic membrane-fusion process to avoid being trapped in endosomes/lysosomes. Thereafter, the GNA remaining in the cytoplasm could reach mitochondria more efficiently via guidance from H₂N-TPP molecules. This "biomembrane-small molecule" combination targeting process was evidenced by fluorescence microscopy, and the highly efficient photothermal ablation of prostatic tumors in vivo was demonstrated. This portfolio targeting strategy could be extended to various nanodrugs/agents to realize an accurate subcellular targeting efficiency for cancer treatments or cell detections.

Curcumin prevents renal cell apoptosis in acute kidney injury in a rat model of dry-heat environment heatstroke via inhibition of the mitochondrial apoptotic pathway

Heatstroke is a life-threatening illness that is characterised by a core body temperature >40^°C and central nervous system dysfunction. Acute kidney injury (AKI) is a common complication of heatstroke, and the mitochondrial apoptotic pathway has been demonstrated to be one of the leading causes of tissue damage and cell death in AKI. Curcumin is a phenol that is extracted from turmeric and demonstrates anti-apoptotic properties. To test if curcumin can protect the kidney from injury caused by heat stress, the effect of curcumin administration on renal injury and apoptosis of renal tissue was examined in a rat model of dry-heat environment. A total of 50 Sprague-Dawley rats were randomly divided into five groups (n=10): Standard temperature control, dry-heat control and curcumin treatment groups (50, 100 and 200 mg/kg groups). After exposure to a dry-heat environment for 150 min, the rats were anesthetized and euthanized. Blood, urine and renal tissue were collected to quantify the expression of specific mitochondrial apoptosis-related molecules. Curcumin pre-treatment decreased blood urea nitrogen and serum creatinine, urinary kidney injury molecule-1, and neutrophil gelatinase-associated lipocalin levels compared with the dry-heat control group. Curcumin was also revealed to downregulate c-Jun N-terminal kinases (JNK), cytochrome c, caspase-3 and caspase-9 expression upon treatment with 100 and 200 mg/kg curcumin, which may result in inhibition of the mitochondrial apoptotic pathway in renal cells. The current study revealed that Curcumin may to have potential for preventing heatstroke-induced AKI.

Precise design strategies of nanomedicine for improving cancer therapeutic efficacy using subcellular targeting

Therapeutic efficacy against cancer relies heavily on the ability of the therapeutic agents to reach their final targets. The optimal targets of most cancer therapeutic agents are usually biological macromolecules at the subcellular level, which play a key role in carcinogenesis. Therefore, to improve the therapeutic efficiency of drugs, researchers need to focus on delivering not only the therapeutic agents to the target tissues and cells but also the drugs to the relevant subcellular structures. In this review, we discuss the most recent construction strategies and release patterns of various cancer cell subcellular-targeting nanoformulations, aiming at providing guidance in the overall design of precise nanomedicine. Additionally, future challenges and potential perspectives are illustrated in the hope of enhancing anticancer efficacy and accelerating the translational progress of precise nanomedicine.

The use of a MITO-Porter to deliver exogenous therapeutic RNA to a mitochondrial disease's cell with a A1555G mutation in the mitochondrial 12S rRNA gene results in an increase in mitochondrial respiratory activity

We report on validating a mitochondrial gene therapeutic strategy using fibroblasts derived from patients with an A1555G point mutation in mitochondrial DNA coding 12S ribosomal RNA (rRNA (12S)). Wild-type rRNA (12S) as a therapeutic RNA was encapsulated in a mitochondrial targeting liposome, a MITO-Porter (rRNA-MITO-Porter), and an attempt was made to deliver the MITO-Porter to mitochondria of the diseased cells. It was confirmed that the rRNA-MITO-Porter treatment significantly decreased the ratio of the mutant rRNA content. Moreover, it was shown that the mitochondrial respiratory activities of the diseased cells were improved as the result of the mitochondrial transfection of the rRNA-MITO-Porter.

A novel dual-targeted rosiglitazone-loaded nanoparticle for the prevention of diet-induced obesity via the browning of white adipose tissue

Adipose tissue in the body is classified as white adipose tissue (WAT); a fat-accumulating tissue, or brown adipose tissue (BAT); an energy-dissipating tissue. Transforming WAT-to-BAT (browning) is a promising strategy for the treatment of obesity, since it would lead to an increase in energy expenditure. Rosiglitazone (Rosi), an agonist of the peroxisome proliferator-activated receptor γ (PPARγ), is known to be a potent browning inducer in subcutaneous WAT. However, the effectiveness of Rosi has been quite limited because of several off-target effects. The objective of this study was to develop locally administered Rosi-loaded nanoparticles (Rs-NPs) with the ability to target adipocytes to achieve the adipose tissue-specific activation of PPARγ, thus causing the browning of WAT. We prepared dual targeted Rs-NPs that were modified with a specific peptide that targets prohibitin that are expressed in adipocytes, and a cell penetrating peptide for enhancing cellular uptake and controlling intracellular trafficking. The Rs-NPs modified with a single ligand were internalized into mature adipocytes and induced browning activity in vitro but they failed to significantly affect the body weight of the diet-induced obese mice model. The dual-targeted Rs-NPs induced a strong browning activity, both in vitro and in vivo, and successfully inhibited the progression of obesity, as evidenced by the shrinkage of hypertrophied adipocytes without any detectable systemic adverse effects. Meanwhile, free Rosi aggravated hepatic steatosis and did not cause adipose tissue browning nor the inhibition of body weight gain. We conclude that the increased energy expenditure via adipose tissue browning using dual-targeted Rs-NP is a promising strategy for the treatment of obesity and its related metabolic syndrome.

Power of mitochondrial drug delivery systems to produce innovative nanomedicines

Mitochondria carry out various essential functions including ATP production, the regulation of apoptosis and possess their own genome (mtDNA). Delivering target molecules to this organelle, it would make it possible to control the functions of cells and living organisms and would allow us to develop a better understanding of life. Given the fact that mitochondrial dysfunction has been implicated in a variety of human disorders, delivering therapeutic molecules to mitochondria for the treatment of these diseases is an important issue. To date, several mitochondrial drug delivery system (DDS) developments have been reported, but a generalized DDS leading to therapy that exclusively targets mitochondria has not been established. This review focuses on mitochondria-targeted therapeutic strategies including antioxidant therapy, cancer therapy, mitochondrial gene therapy and cell transplantation therapy based on mitochondrial DDS. A particular focus is on nanocarriers for mitochondrial delivery with the goal of achieving mitochondria-targeting therapy. We hope that this review will stimulate the accelerated development of mitochondrial DDS.

Evolution of drug delivery system from viewpoint of controlled intracellular trafficking and selective tissue targeting toward future nanomedicine

Due to the rapid changes that have occurred in the field of drug discovery and the recent developments in the early 21st century, the role of drug delivery systems (DDS) has become increasingly more important. For the past 20 years, our laboratory has been developing gene delivery systems based on lipid-based delivery systems. One of our efforts has been directed toward developing a multifunctional envelope-type nano device (MEND) by modifying the particle surface with octaarginine, which resulted in a remarkably enhanced cellular uptake and improved intracellular trafficking of plasmid DNA (pDNA). When we moved to in vivo applications, however, we were faced with the PEG-dilemma and we shifted our strategy to the incorporation of ionizable cationic lipids into our system. This resulted in some dramatic improvements over our original design and this can be attributed to the development of a new lipid library. We have also developed a mitochondrial targeting system based on a membrane fusion mechanism using a MITO-Porter, which can deliver nucleic acids/pDNA into the matrix of mitochondria. After the appearance of antibody medicines, Opdivo, an immune checkpoint inhibitor, has established cancer immunology as the 4th strategy in cancer therapy. Our DDS technologies can also be applied to this new field of cancer therapy to cure cancer by controlling our immune mechanisms. The latest studies are summarized in this review article.

Challenges in Promoting Mitochondrial Transplantation Therapy

Mitochondrial transplantation therapy is an innovative strategy for the treatment of mitochondrial dysfunction. The approach has been reported to be useful in the treatment of cardiac ischemic reperfusion injuries in human clinical trials and has also been shown to be useful in animal studies as a method for treating mitochondrial dysfunction in various tissues, including the heart, liver, lungs, and brain. On the other hand, there is no methodology for using preserved mitochondria. Research into the pharmaceutical formulation of mitochondria to promote mitochondrial transplantation therapy as the next step in treating many patients is urgently needed. In this review, we overview previous studies on the therapeutic effects of mitochondrial transplantation. We also discuss studies related to immune responses that occur during mitochondrial transplantation and methods for preserving mitochondria, which are key to their stability as medicines. Finally, we describe research related to mitochondrial targeting drug delivery systems (DDS) and discuss future perspectives of mitochondrial transplantation.

Rational Construction of a Mitochondrial Targeting, Fluorescent Self-Reporting Drug-Delivery Platform for Combined Enhancement of Endogenous ROS Responsiveness

To maximize the utilization and response to the high oxidative stress environment of tumor sites while avoiding the dilemma of enhancing reactive oxygen species (ROS) response in a single way, mitochondrial targeting combined with fluorescent self-reporting polymeric nanocarriers (1K-TPP and 2K-TPP) with grafted structures were synthesized via a chemoenzymatic method in a high yield to simultaneously enhance the drug delivery of endogenous ROS responses. 1K-TPP and 2K-TPP loaded doxorubicin (DOX) at a high content over 12% and formed homogeneous spherical micelles. In vitro, both of them showed promising high sensitivity (detection limit below 200 nM H₂O₂), fast response, and ratiometric fluorescent self-reporting properties (fluorescent enhancement more than 200 times) to ROS and excellent stability under physiological conditions, while achieving a rapid release of the DOX in response to 1 mM H₂O₂. Cell co-localization experiments exhibited that they had favorable mitochondrial targeting, and mitochondrial isolation experiments also confirmed that the TPP-modified 1K-TPP selectively accumulated nearly three times in mitochondria than that in total cells. The internalization of 1K-TPP and 2K-TPP into cancer cells was greatly improved by nearly 200% compared to that of unmodified control (1K-OH and 2K-OH) and also explored a unique energy-dependent endocytosis. Furthermore, stimulation of endogenous ROS enhanced the green fluorescence intensity (up to 51.4%) of the linked probe so as to destroy the internal structure of the nanocarriers, achieving self-reporting of the drug's intracellular release and tracking of the intracellular location of nanocarriers. The cytotoxicity of DOX-loaded 1K-TPP and 2K-TPP in tumor cells with a higher ROS content showed statistical superiority to that of 1K-OH and 2K-OH, benefiting from the extremely good endogenous ROS response sensitivity leading to the differential selective release of drugs. These results demonstrate the potential of 1K-TPP and 2K-TPP, especially for 1K-TPP, as mitochondria-targeted, fluorescent self-reporting nanocarriers for combined enhancement of endogenous ROS responsiveness.

A novel mitochondrial targeted hybrid peptide modified HPMA copolymers for breast cancer metastasis suppression

Primary tumor metastasis remains to be a tough obstacle for clinical breast cancer treatment. Since evidences have shown that mitochondria play a crucial role in tumor metastasis, we designed a mitochondrial targeted drug delivery system (P-D-R8MTS) based on N-(2-hydroxypropyl) methacrylamide (HPMA) copolymers to simultaneously inhibit breast cancer progression and metastasis. A novel mitochondrial targeted hybrid peptide R8MTS, which consists of a cell penetrating peptide octaarginine (R8) and a mitochondrial targeting sequence ALD5^MTS, was used as targeting ligand and attached to doxorubicin (DOX) as model drug (DOX-R8MTS). After entering into the tumor cells, DOX-R8MTS was pH-responsibly released from HPMA copolymer backbone in acidic lysosome and efficiently targeted to mitochondria, resulting in enhanced reactive oxygen species (ROS) generation and apoptosis initiation. By destroying mitochondria, P-D-R8MTS not only inhibited cell proliferation but also suppressed migration and invasion of breast cancer 4T1 and MDA-MB-231 cells in vitro. Moreover, P-D-R8MTS exhibited superior inhibition of tumor growth and showed no apparent lung metastatic nodules on 4T1-bearing mice in vivo, which was partially via down-regulation of typical proteins associated with tumor metastasis and invasion: matrix metalloproteinases-2 (MMP-2), vascular endothelial growth factor (VEGF) and transforming growth factor-β (TGF-β). Collectively, our work provided a prospectively potential strategy for metastatic cancer treatment through mitochondrial targeted drug delivery.

Dendritic Mesoporous Organosilica Nanoparticles: A pH-Triggered Autocatalytic Fenton Reaction System with Self-supplied H2O2 for Generation of High Levels of Reactive Oxygen Species

Dendritic mesoporous silica nanoparticles represent a new biomedical application platform due to their special central radial pore structure for the loading of drugs and functional modification. Herein, we report functionalized dendritic mesoporous organosilica nanoparticles (DMONs), a pH-triggered Fenton reaction generator (TA/Fe@GOD@DMONs), incorporating natural glucose oxidase (GOD) in the DMONs with tannic acid (TA) grafted using Fe³⁺ on the surface, that have been designed and constructed for efficient tumor ablation with self-supplied H₂O₂ and accelerated conversion of Fe³⁺/Fe²⁺ by TA. In view of the deficiency of endogenous H₂O₂, the self-supply through the TA/Fe@GOD@DMONs platform represented a high-yielding source of peroxygen. Furthermore, the production of Fe²⁺ induced by TA greatly improved the efficiency of the Fenton reaction resulting in significant tumor inhibition. This new design represents as novel paradigm for the development of autocatalytic Fenton nanosystems for effective treatment of tumors.

Validation of a mitochondrial RNA therapeutic strategy using fibroblasts from a Leigh syndrome patient with a mutation in the mitochondrial ND3 gene

We report on the validation of a mitochondrial gene therapeutic strategy using fibroblasts from a Leigh syndrome patient by the mitochondrial delivery of therapeutic mRNA. The treatment involves delivering normal ND3 protein-encoding mRNA as a therapeutic RNA to mitochondria of the fibroblasts from a patient with a T10158C mutation in the mtDNA coding the ND3 protein, a component of the mitochondrial respiratory chain complex I. The treatment involved the use of a liposome-based carrier (a MITO-Porter) for delivering therapeutic RNA to mitochondria via membrane fusion. The results confirmed that the mitochondrial transfection of therapeutic RNA by the MITO-Porter system resulted in a decrease in the levels of mutant RNA in mitochondria of diseased cells based on reverse transcription quantitative PCR. An evaluation of mitochondrial respiratory activity by respirometry also showed that transfection using the MITO-Porter resulted in an increase in maximal mitochondrial respiratory activity in the diseased cells.