Liver-Targeted Delivery of Small Interfering RNA of C-C Chemokine Receptor 2 with Tetrahedral Framework Nucleic Acid Attenuates Liver Cirrhosis

Cutting-edge biotherapeutics and advanced delivery strategies for the treatment of metabolic dysfunction-associated steatotic liver disease spectrum

Metabolic dysfunction-associated steatotic liver disease (MASLD), a condition with the potential to progress into liver cirrhosis or hepatocellular carcinoma, has become a significant global health concern due to its increasing prevalence alongside obesity and metabolic syndrome. Despite the promise of existing therapies such as thyroid hormone receptor-β (THR-β) agonists, PPAR agonists, FXR agonists, and GLP-1 receptor agonists, their effectiveness is limited by the complexity of the metabolic, inflammatory, and fibrotic pathways that drive MASLD progression, encompassing steatosis, metabolic dysfunction-associated steatohepatitis (MASH), and reversible liver fibrosis. Recent advances in targeted therapeutics, including RNA interference (RNAi), mRNA-based gene therapies, monoclonal antibodies, proteolysis-targeting chimeras (PROTAC), peptide-based strategies, cell-based therapies such as CAR-modified immune cells and stem cells, and extracellular vesicle-based approaches, have emerged as promising interventions. Alongside these developments, innovative drug delivery systems are being actively researched to enhance the stability, precision, and therapeutic efficacy of these biotherapeutics. These delivery strategies aim to optimize biodistribution, improve target-specific action, and reduce systemic exposure, thus addressing critical limitations of existing treatment modalities. This review provides a comprehensive exploration of the underlying biological mechanisms of MASLD and evaluates the potential of these cutting-edge biotherapeutics in synergy with advanced delivery approaches to address unmet clinical needs. By integrating fundamental disease biology with translational advancements, it aims to highlight future directions for the development of effective, targeted treatments for MASLD and its associated complications.

Unveiling the Potential of Tetrahedral DNA Frameworks in Clinical Medicine: Mechanisms, Advances, and Future Perspectives

As deoxyribonucleic acis (DNA) nanotechnology advances, DNA, a fundamental biological macromolecule, has been employed to treat various clinical diseases. Among the advancements in this field, tetrahedral frameworks nucleic acids (tFNAs) have gained significant attention due to their straightforward design, structural simplicity, low cost, and high yield since their introduction by Turberfield in the early 2000s. Due to its stable spatial structure, tFNAs can resist the impact of innate immune responses on DNA and nuclease activity. Meanwhile, structural programmability of tFNAs allows for the development of static tFNA-based nanomaterials through the engineering of functional oligonucleotides or therapeutic molecules and dynamic tFNAs through the attachment of stimuli-responsive DNA apparatuses. This review first summarizes the key merits of tFNAs, including natural biocompatibility, biodegradability, structural stability, unparalleled programmability, functional diversity, and efficient cellular internalization. Based on these strengths, this review comprehensively analyzes applications of tFNAs in different clinical settings, including orthopedics, stomatology, urinary system diseases, liver-related diseases, tumors, infection, neural system diseases, ophthalmic diseases, and immunoprophylaxis. We also discuss the limitations of tFNAs and the challenges encountered in preclinical studies. This review provides new perspectives for future research and valuable guidance for researchers working in this field.

A bioswitchable delivery system for microRNA therapeutics based on a tetrahedral DNA nanostructure

As microRNAs (miRNA) regulate almost all physiopathological activities in the human body, miRNA therapeutics that deliver miRNA regulators have attracted considerable attention in the field of nucleic acid drug development. The use of tetrahedral DNA nanostructures to deliver miRNA regulators is promising because of their simple fabrication, enhanced cell entry, effective tissue penetration, biocompatibility and functional editability. This protocol extension builds on our previous protocol for the use of tetrahedral DNA nanostructures and was designed to establish an updated bioswitchable delivery system (BDS) for achieving controlled cargo loading and release. A ribonuclease H-sensitive sequence is designed as a bioswitchable apparatus for the targeted release of the miRNA regulator. The functional sequence of the miRNA regulator and minimal secondary structure formation tendency during annealing are two key points in cargo design. We provide two BDS design strategies; BDS-A comprises an intact DNA tetrahedron with the RNA cargo hanging outside, offering the merits of lower cost, simplicity, and more direct structural design. In the BDS-B design, the RNA regulators are embedded into the DNA tetrahedron, which is beneficial for dermal tissue permeation applications. Following sequence design in Oligo 7 and Tiamat, the BDS assembly is completed and then ribonuclease H achieves controlled release of the miRNA regulator by triggering the bioswitchable apparatus. This is verified via polyacrylamide and agarose gel electrophoresis or fluorophore modifications. Both BDSs show promising cellular membrane permeability, tissue permeability and target inhibition in vitro and in vivo. The assembly and characterization of the BDS can be completed in 4 d, and the validation time for biostability and biological applications will depend on the specific use.

The role and therapeutic targeting of the CCL2/CCR2 signaling axis in inflammatory and fibrotic diseases

CCL2, a pivotal cytokine within the chemokine family, functions by binding to its receptor CCR2. The CCL2/CCR2 signaling pathway plays a crucial role in the development of fibrosis across multiple organ systems by modulating the recruitment and activation of immune cells, which in turn influences the progression of fibrotic diseases in the liver, intestines, pancreas, heart, lungs, kidneys, and other organs. This paper introduces the biological functions of CCL2 and CCR2, highlighting their similarities and differences concerning fibrotic disorders in various organ systems, and reviews recent progress in the diagnosis and treatment of clinical fibrotic diseases linked to the CCL2/CCR2 signaling pathway. Additionally, further in-depth research is needed to explore the clinical significance of the CCL2/CCR2 axis in fibrotic conditions affecting different organs.

In Vivo Interactions of Nucleic Acid Nanostructures With Cells

Nucleic acid nanostructures, derived from the assembly of nucleic acid building blocks (e.g., plasmids and oligonucleotides), are important intracellular carriers of therapeutic cargoes widely utilized in preclinical nanomedicine applications, yet their clinical translation remains scarce. In the era of "translational nucleic acid nanotechnology", a deeper mechanistic understanding of the interactions of nucleic acid nanostructures with cells in vivo will guide the development of more efficacious nanomedicines. This review showcases the recent progress in dissecting the in vivo interactions of four key types of nucleic acid nanostructures (i.e., tile-based, origami, spherical nucleic acid, and nucleic acid nanogel) with cells in rodents over the past five years. Emphasis lies on the cellular-level distribution of nucleic acid nanostructures in various organs and tissues and the cellular responses induced by their cellular entry. Next, in the spirit of preclinical translation, this review features the latest interactions of nucleic acid nanostructures with cells in large animals and humans. Finally, the review offers directions for studying the interactions of nucleic acid nanostructures with cells from both materials and biology perspectives and concludes with some regulatory updates.

A Binary siRNA-Loaded Tetrahedral DNA Nanobox for Synergetic Anti-Aging Therapy

Extensive accumulation of senescent cells contributes to organismal aging, and slowing down the process of cellular senescence may ameliorate age-related pathologies. Targeted inhibition of the mechanistic target of rapamycin complex 1 (mTORC1) is found to suppress the conversion of cells to senescence. The regulatory-associated protein of mTOR (Raptor), a key component of mTORC1, has been implicated as important in the aging process, and its druggability deserves to be investigated. Due to high efficiency and high convenience in drug construction, siRNA shows great potential in silencing Raptor expression via RNA interfering therapy. Here, we developed a functionalized anti-aging nanoplatform based on tetrahedral DNA nanostructures (TDNs) encapsulating siRNA targeting Raptor for synergistic anti-aging therapy, named siR-TDNbox. Anti-inflammatory and antioxidant properties of TDN beneficially attenuate age-associated inflammation while serving as siRNA nanocarrier, and thus play a binary role. The results suggest that the siR-TDNbox binary therapeutic nanoplatform has demonstrated an excellent ability to delay aging, inhibit mTORC1 signaling, and extend lifespan. This anti-aging nanoplatform may provide a medium for the combined application of traditional senotherapeutic drugs and promote the upgrading of nanomaterials with anti-aging effects.

Progressive cancer targeting by programmable aptamer-tethered nanostructures

Scientific research in recent decades has affirmed an increase in cancer incidence as a cause of death globally. Cancer can be considered a plurality of various diseases rather than a single disease, which can be a multifaceted problem. Hence, cancer therapy techniques acquired more accelerated and urgent approvals compared to other therapeutic approaches. Radiotherapy, chemotherapy, immunotherapy, and surgery have been widely adopted as routine cancer treatment strategies to suppress disease progression and metastasis. These therapeutic approaches have lengthened the longevity of countless cancer patients. Nonetheless, some inherent limitations have restricted their application, including insignificant therapeutic efficacy, toxicity, negligible targeting, non-specific distribution, and multidrug resistance. The development of therapeutic oligomer nanoconstructs with the advantages of chemical solid-phase synthesis, programmable design, and precise adjustment is crucial for advancing smart targeted drug nanocarriers. This review focuses on the significance of the different aptamer-assembled nanoconstructs as multifunctional nucleic acid oligomeric nanoskeletons in efficient drug delivery. We discuss recent advancements in the design and utilization of aptamer-tethered nanostructures to enhance the efficacy of cancer treatment. Valuably, this comprehensive review highlights self-assembled aptamers as the exceptionally intelligent nano-biomaterials for targeted drug delivery based on their superior stability, high specificity, excellent recoverability, inherent biocompatibility, and versatile functions.

A Bioswitchable MiRNA Delivery System: Tetrahedral Framework DNA-Based miRNA Delivery System for Applications in Wound Healing

The human body's primary line of defense, the skin, is especially prone to harm. Although microRNA (miRNA)-based therapies have attracted increasing attention for skin wound healing, their applications remain limited owing to a range of issues. Tetrahedral framework DNA (tFNA), a nanomaterial possessing nucleic acid characteristics, exhibits an excellent biocompatibility, in addition to anti-inflammatory and transdermal delivery capabilities, and can accelerate skin wound healing. Due to its potential to exert synergistic action with therapeutic miRNA, tFNA has been considered an ideal vehicle for miRNA therapy. The design and synthesis of a bioswitchable miRNA delivery system (BiRDS) is reported, which contains three miRNAs as well as a nucleic acid core to maximize the loading capacity while preserving the characteristics of tFNA. A high stability, excellent permeability of cells as well as tissues and good biological compatibility are demonstrated. By selectively inhibiting heparin-binding epidermal growth factor (HB-EGF), the BiRDS can inhibit the NF-κB pathway while simultaneously controlling the PTEN/Akt pathway. As a result, the BiRDS helps wound healing go through the inflammation to the proliferative phase. This study demonstrates the advantages of the BiRDS in miRNA-based therapy and provides new research ideas for the treatment of skin-related diseases.

Framework nucleic acids as promising reactive oxygen species scavengers for anti-inflammatory therapy

Reactive oxygen species (ROS) are an array of derivatives of molecular oxygen that participate in multiple physiological processes under the control of redox homeostasis. However, under pathological conditions, the over-production of ROS often leads to oxidative stress and inflammatory reactions, indicating a potential therapeutic target. With the rapid development of nucleic acid nanotechnology, scientists have exploited various DNA nanostructures with remarkable biocompatibility, programmability, and structural stability. Among these novel organic nanomaterials, a group of skeleton-like framework nucleic acid (FNA) nanostructures attracts the most interest due to their outstanding self-assembly, cellular endocytosis, addressability, and functionality. Surprisingly, different FNAs manifest similarly satisfactory antioxidative and anti-inflammatory effects during their biomedical application process. First, they are intrinsically endowed with the ability to neutralize ROS due to their DNA nature. Therefore, they are extensively involved in the complicated inflammatory signaling network. Moreover, the outstanding editability of FNAs also allows for flexible modifications with nucleic acids, aptamers, peptides, antibodies, low-molecular-weight drugs, and so on, thus further strengthening the targeting and therapeutic ability. This review focuses on the ROS-scavenging potential of three representative FNAs, including tetrahedral framework nucleic acids (tFNAs), DNA origami, and DNA hydrogels, to summarize the recent advances in their anti-inflammatory therapy applications. Although FNAs exhibit great potential in treating inflammatory diseases as promising ROS scavengers, massive efforts still need to be made to overcome the emerging challenges in their clinical translation.

Sevelamer reverses liver fibrosis by deactivation of hepatic stellate cells

Liver fibrosis is a chronic liver disease characterized by a progressive wound healing response caused by chronic liver injury. Currently, there are no approved clinical treatments for liver fibrosis. Sevelamer is used clinically to treat hyperphosphatemia and has shown potential therapeutic effects on liver diseases. However, there have been few studies evaluating the therapeutic effects of sevelamer on liver fibrosis, and the specific mechanisms are still unclear. In this study, we investigated the antifibrotic effects of sevelamer-induced low inorganic phosphate (Pi) stress in vitro and in vivo and analyzed the detailed mechanisms. We found that low Pi stress could inhibit the proliferation of activated hepatic stellate cells (HSCs) by promoting apoptosis, effectively suppressing the migration and epithelial-mesenchymal transition (EMT) of hepatic stellate cells. Additionally, low Pi stress significantly increased the antioxidant stress response. It is worth noting that low Pi stress indirectly inhibited the activation and migration of HSCs by suppressing transforming growth factor β (TGF-β) expression in macrophages. In a rat model of liver fibrosis, oral administration of sevelamer significantly decreased blood phosphorus levels, improved liver function, reduced liver inflammation, and increased the antioxidant stress response in the liver. Our study revealed that the key mechanism by which sevelamer inhibited liver fibrosis involved binding to gastrointestinal phosphate, resulting in a decrease in blood phosphorus levels, the downregulation of TGF-β expression in macrophages, and the inhibition of HSC migration and fibrosis-related protein expression. Therefore, our results suggest that sevelamer-induced low Pi stress can attenuate hepatic stellate cell activation and inhibit the progression of liver fibrosis, making it a potential option for the treatment of liver fibrosis and other refractory chronic liver diseases.

Macrophages and platelets in liver fibrosis and hepatocellular carcinoma

During fibrosis, (myo)fibroblasts deposit large amounts of extracellular matrix proteins, thereby replacing healthy functional tissue. In liver fibrosis, this leads to the loss of hepatocyte function, portal hypertension, variceal bleeding, and increased susceptibility to infection. At an early stage, liver fibrosis is a dynamic and reversible process, however, from the cirrhotic stage, there is significant progression to hepatocellular carcinoma. Both liver-resident macrophages (Kupffer cells) and monocyte-derived macrophages are important drivers of fibrosis progression, but can also induce its regression once triggers of chronic inflammation are eliminated. In liver cancer, they are attracted to the tumor site to become tumor-associated macrophages (TAMs) polarized towards a M2- anti-inflammatory/tumor-promoting phenotype. Besides their role in thrombosis and hemostasis, platelets can also stimulate fibrosis and tumor development by secreting profibrogenic factors and regulating the innate immune response, e.g., by interacting with monocytes and macrophages. Here, we review recent literature on the role of macrophages and platelets and their interplay in liver fibrosis and hepatocellular carcinoma.

RNA Nanomedicine: Delivery Strategies and Applications

Delivery of RNA using nanomaterials has emerged as a new modality to expand therapeutic applications in biomedical research. However, the delivery of RNA presents unique challenges due to its susceptibility to degradation and the requirement for efficient intracellular delivery. The integration of nanotechnologies with RNA delivery has addressed many of these challenges. In this review, we discuss different strategies employed in the design and development of nanomaterials for RNA delivery. We also highlight recent advances in the pharmaceutical applications of RNA delivered via nanomaterials. Various nanomaterials, such as lipids, polymers, peptides, nucleic acids, and inorganic nanomaterials, have been utilized for delivering functional RNAs, including messenger RNA (mRNA), small interfering RNA, single guide RNA, and microRNA. Furthermore, the utilization of nanomaterials has expanded the applications of functional RNA as active pharmaceutical ingredients. For instance, the delivery of antigen-encoding mRNA using nanomaterials enables the transient expression of vaccine antigens, leading to immunogenicity and prevention against infectious diseases. Additionally, nanomaterial-mediated RNA delivery has been investigated for engineering cells to express exogenous functional proteins. Nanomaterials have also been employed for co-delivering single guide RNA and mRNA to facilitate gene editing of genetic diseases. Apart from the progress made in RNA medicine, we discuss the current challenges and future directions in this field.

Recent progress and application of the tetrahedral framework nucleic acid materials on drug delivery

INTRODUCTION

The application of DNA framework nucleic acid materials in the biomedical field has witnessed continual expansion. Among them, tetrahedral framework nucleic acids (tFNAs) have gained significant traction as the foremost biological vectors due to their superior attributes of editability, low immunogenicity, biocompatibility, and biodegradability. tFNAs have demonstrated promising results in numerous in vitro and in vivo applications.

AREAS COVERED

This review summarizes the latest research on tFNAs in drug delivery, including a discussion of the advantages of tFNAs in regulating biological behaviors, and highlights the updated development and advantageous applications of tFNAs-based nanostructures from static design to dynamically responsive design.

EXPERT OPINION

tFNAs possess distinct biological regulatory attributes and can be taken up by cells without the requirement of transfection, differentiating them from other biological vectors. tFNAs can be easily physically/chemically modified and seamlessly incorporated with other functional systems. The static design of the tFNAs-based drug delivery system makes it versatile, reproducible, and predictable. Further use of the dynamic response mechanism of DNA to external stimuli makes tFNAs-based drug delivery more effective and specific, improving the uptake and utilization of the payload by the intended target. Dynamic targeting is poised to become the future primary approach for drug delivery.

Treatment of liver fibrosis: Past, current, and future

Liver fibrosis accompanies the progression of chronic liver diseases independent of etiologies, such as hepatitis viral infection, alcohol consumption, and metabolic-associated fatty liver disease. It is commonly associated with liver injury, inflammation, and cell death. Liver fibrosis is characterized by abnormal accumulation of extracellular matrix components that are expressed by liver myofibroblasts such as collagens and alpha-smooth actin proteins. Activated hepatic stellate cells contribute to the major population of myofibroblasts. Many treatments for liver fibrosis have been investigated in clinical trials, including dietary supplementation (e.g., vitamin C), biological treatment (e.g., simtuzumab), drug (e.g., pegbelfermin and natural herbs), genetic regulation (e.g., non-coding RNAs), and transplantation of stem cells (e.g., hematopoietic stem cells). However, none of these treatments has been approved by Food and Drug Administration. The treatment efficacy can be evaluated by histological staining methods, imaging methods, and serum biomarkers, as well as fibrosis scoring systems, such as fibrosis-4 index, aspartate aminotransferase to platelet ratio, and non-alcoholic fatty liver disease fibrosis score. Furthermore, the reverse of liver fibrosis is slowly and frequently impossible for advanced fibrosis or cirrhosis. To avoid the life-threatening stage of liver fibrosis, anti-fibrotic treatments, especially for combined behavior prevention, biological treatment, drugs or herb medicines, and dietary regulation are needed. This review summarizes the past studies and current and future treatments for liver fibrosis.

Mechanism-based target therapy in primary biliary cholangitis: opportunities before liver cirrhosis?

Primary biliary cholangitis (PBC) is an immune-mediated liver disease characterized by cholestasis, biliary injuries, liver fibrosis, and chronic non-suppurative cholangitis. The pathogenesis of PBC is multifactorial and involves immune dysregulation, abnormal bile metabolism, and progressive fibrosis, ultimately leading to cirrhosis and liver failure. Ursodeoxycholic acid (UDCA) and obeticholic acid (OCA) are currently used as first- and second-line treatments, respectively. However, many patients do not respond adequately to UDCA, and the long-term effects of these drugs are limited. Recent research has advanced our understanding the mechanisms of pathogenesis in PBC and greatly facilitated development of novel drugs to target mechanistic checkpoints. Animal studies and clinical trials of pipeline drugs have yielded promising results in slowing disease progression. Targeting immune mediated pathogenesis and anti-inflammatory therapies are focused on the early stage, while anti-cholestatic and anti-fibrotic therapies are emphasized in the late stage of disease, which is characterized by fibrosis and cirrhosis development. Nonetheless, it is worth noting that currently, there exists a dearth of therapeutic options that can effectively impede the progression of the disease to its terminal stages. Hence, there is an urgent need for further research aimed at investigating the underlying pathophysiology mechanisms with potential therapeutic effects. This review highlights our current knowledge of the underlying immunological and cellular mechanisms of pathogenesis in PBC. Further, we also address current mechanism-based target therapies for PBC and potential therapeutic strategies to improve the efficacy of existing treatments.