A nanocarrier for the mitochondrial delivery of nucleic acids to cardiomyocytes

Noncoding RNA as potential therapeutics to rescue mitochondrial dysfunction in cardiovascular diseases

Noncoding RNAs (ncRNAs) are critical regulators of mitochondrial function in cardiovascular diseases. Several studies have explored the manipulation of ncRNAs in mitochondrial dysfunction in different cardiovascular disease contexts, however, there is a dearth of information on the exploration of these noncoding RNAs as actual therapeutics to ameliorate cardiovascular diseases. This systematic review examines the roles of various ncRNAs in modulating mitochondrial dysfunction across major cardiovascular diseases and how they can be targeted to the mitochondria. A comprehensive literature search was conducted using Web of Science and Scopus databases, following the PRISMA guidelines. Original research articles in the English language, focusing on ncRNAs and mitochondrial dysfunction in specific cardiovascular diseases, were eligible for inclusion. A total of 76 studies were included in the systematic review with up to 100 ncRNAs identified as therapeutic biomarkers. The identified ncRNAs participate in regulating mitochondrial processes including oxidative phosphorylation (OXPHOS), fission/fusion dynamics, apoptosis, and calcium handling in cardiovascular diseases. Mitochondrial targeting moieties including mitochondrial targeting cell-penetrating peptides, mitochondrial targeting liposomes, and aptamers can be conjugated to ncRNAs and delivered to the heart via various injection routes including the pericardium or the myocardium. However, significant challenges remain in developing effective delivery methods to modulate these ncRNAs in vivo.

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.

Resveratrol-Encapsulated Mitochondria-Targeting Liposome Enhances Mitochondrial Respiratory Capacity in Myocardial Cells

The development of drug delivery systems for use in the treatment of cardiovascular diseases is an area of great interest. We report herein on an evaluation of the therapeutic potential of a myocardial mitochondria-targeting liposome, a multifunctional envelope-type nano device for targeting pancreatic β cells (β-MEND) that was previously developed in our laboratory. Resveratrol (RES), a natural polyphenol compound that has a cardioprotective effect, was encapsulated in the β-MEND (β-MEND (RES)), and its efficacy was evaluated using rat myocardioblasts (H9c2 cells). The β-MEND (RES) was readily taken up by H9c2 cells, as verified by fluorescence-activated cell sorter data, and was observed to be colocalized with intracellular mitochondria by confocal laser scanning microscopy. Myocardial mitochondrial function was evaluated by a Seahorse XF Analyzer and the results showed that the β-MEND (RES) significantly activated cellular maximal respiratory capacity. In addition, the β-MEND (RES) showed no cellular toxicity for H9c2 cells as evidenced by Premix WST-1 assays. This is the first report of the use of a myocardial mitochondria-targeting liposome encapsulating RES for activating mitochondrial function, which was clearly confirmed based on analyses using a Seahorse XF Analyzer.

Validation of the mitochondrial delivery of vitamin B1 to enhance ATP production using SH-SY5Y cells, a model neuroblast

Large amounts of ATP are produced in mitochondria especially in the brain and heart, where energy consumption is high compared with other organs. Thus, a decrease in ATP production in such organs could be a cause of many diseases such as neurodegenerative diseases and heart disease. Based on thus assumption, increasing intracellular ATP production in such organs could be a therapeutic strategy. In this study, we report on the delivery of vitamin B₁, a coenzyme that activates the tricarboxylic acid (TCA) cycle, to the inside of mitochondria. Since the TCA cycle is responsible for ATP production, we hypothesized delivering vitamin B₁ to mitochondria would enhance ATP production. To accomplish this, we used a mitochondrial targeted liposome a "MITO-Porter" as the carrier. Using SH-SY5Y cells, a model neuroblast, cellular uptake and intracellular localization were analyzed using flow cytometry and confocal laser scanning microscopy. The optimized MITO-Porter containing encapsulated vitamin B₁ (MITO-Porter (VB₁)) was efficiently accumulated in mitochondria of SH-SY5Y cells. Further studies confirmed that the level of ATP production after the MITO-Porter (VB₁) treatment was significantly increased as compared to a control group that was treated with naked vitamin B₁. This study provides the potential for an innovative therapeutic strategy in which the TCA cycle is activated, thus enhancing ATP production.

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.

Mitochondria-Targeted Polyamidoamine Dendrimer-Curcumin Construct for Hepatocellular Cancer Treatment

Mitochondrial malfunction plays a crucial role in cancer development and progression. Cancer cells show a substantially higher mitochondrial activity and greater mitochondrial transmembrane potential than normal cells. This concept can be exploited for targeting cytotoxic drugs to the mitochondria of cancer cells using mitochondrial-targeting compounds. In this study, a polyamidoamine dendrimer-based mitochondrial delivery system was prepared for curcumin using triphenylphosphonium ligands to improve the anticancer efficacy of the drug in vitro and in vivo. For the in vitro evaluations, various methods, such as viability assay, confocal microscopy, flow cytometry, reactive oxygen species (ROS), and real-time polymerase chain reaction analyses, were applied. Our findings showed that the targeted-dendrimeric curcumin (TDC) could successfully deliver and colocalize the drug to the mitochondria of the cancer cells, and selectively induce a potent apoptosis and cell cycle arrest at G2/M. Moreover, at a low curcumin dose of less than 25 μM, TDC significantly reduced adenosine triphosphate and glutathione, and increased the ROS level of the isolated rat hepatocyte mitochondria. The in vivo studies on the Hepa1-6 tumor-bearing mice also indicated a significant tumor suppression effect and the highest median survival days (Kaplan-Meier survival estimation and log-rank test) after treatment with the TDC construct compared to the free curcumin and untargeted construct. Besides its targeted nature and safety, the expected improved solubility and stability represent the prepared targeted-dendrimeric construct as an up-and-coming candidate for cancer treatment. The results of this study emphasize the promising route of mitochondrial targeting as a practical approach for cancer therapy, which can be achieved by optimizing the delivery method.

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.

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.