Tetrahedral Framework Nucleic Acids Reestablish Immune Tolerance and Restore Saliva Secretion in a Sjögren's Syndrome Mouse Model

A Novel Bioswitchable miRNA Mimic Delivery System: Therapeutic Strategies Upgraded from Tetrahedral Framework Nucleic Acid System for Fibrotic Disease Treatment and Pyroptosis Pathway Inhibition

There has been considerable interest in gene vectors and their role in regulating cellular activities and treating diseases since the advent of nucleic acid drugs. MicroRNA (miR) therapeutic strategies are research hotspots as they regulate gene expression post-transcriptionally and treat a range of diseases. An original tetrahedral framework nucleic acid (tFNA) analog, a bioswitchable miR inhibitor delivery system (BiRDS) carrying miR inhibitors, is previously established; however, it remains unknown whether BiRDS can be equipped with miR mimics. Taking advantage of the transport capacity of tetrahedral framework nucleic acid (tFNA) and upgrading it further, the treatment outcomes of a traditional tFNA and BiRDS at different concentrations on TGF-β- and bleomycin-induced fibrosis simultaneously in vitro and in vivo are compared. An upgraded traditional tFNA is designed by successfully synthesizing a novel BiRDS, carrying a miR mimic, miR-27a, for treating skin fibrosis and inhibiting the pyroptosis pathway, which exhibits stability and biocompatibility. BiRDS has three times higher efficiency in delivering miRNAs than the conventional tFNA with sticky ends. Moreover, BiRDS is more potent against fibrosis and pyroptosis-related diseases than tFNAs. These findings indicate that the BiRDS can be applied as a drug delivery system for disease treatment.

The Current Progress of Tetrahedral DNA Nanostructure for Antibacterial Application and Bone Tissue Regeneration

Recently, programmable assembly technologies have enabled the application of DNA in the creation of new nanomaterials with unprecedented functionality. One of the most common DNA nanostructures is the tetrahedral DNA nanostructure (TDN), which has attracted great interest worldwide due to its high stability, simple assembly procedure, high predictability, perfect programmability, and excellent biocompatibility. The unique spatial structure of TDN allows it to penetrate cell membranes in abundance and regulate cellular biological properties as a natural genetic material. Previous studies have demonstrated that TDNs can regulate various cellular biological properties, including promoting cells proliferation, migration and differentiation, inhibiting cells apoptosis, as well as possessing anti-inflammation and immunomodulatory capabilities. Furthermore, functional molecules can be easily modified at the vertices of DNA tetrahedron, DNA double helix structure, DNA tetrahedral arms or DNA tetrahedral cage structure, enabling TDN to be used as a nanocarrier for a variety of biological applications, including targeted therapies, molecular diagnosis, biosensing, antibacterial treatment, antitumor strategies, and tissue regeneration. In this review, we mainly focus on the current progress of TDN-based nanomaterials for antimicrobial applications, bone and cartilage tissue repair and regeneration. The synthesis and characterization of TDN, as well as the biological merits are introduced. In addition, the challenges and prospects of TDN-based nanomaterials are also discussed.

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.

Exosome inspired photo-triggered gelation hydrogel composite on modulating immune pathogenesis for treating rheumatoid arthritis

Although exosome therapy has been recognized as a promising strategy in the treatment of rheumatoid arthritis (RA), sustained modulation on RA specific pathogenesis and desirable protective effects for attenuating joint destruction still remain challenges. Here, silk fibroin hydrogel encapsulated with olfactory ecto-mesenchymal stem cell-derived exosomes (Exos@SFMA) was photo-crosslinked in situ to yield long-lasting therapeutic effect on modulating the immune microenvironment in RA. This in situ hydrogel system exhibited flexible mechanical properties and excellent biocompatibility for protecting tissue surfaces in joint. Moreover, the promising PD-L1 expression was identified on the exosomes, which potently suppressed Tfh cell polarization via inhibiting the PI3K/AKT pathway. Importantly, Exos@SFMA effectively relieved synovial inflammation and joint destruction by significantly reducing T follicular helper (Tfh) cell response and further suppressing the differentiation of germinal center (GC) B cells into plasma cells. Taken together, this exosome enhanced silk fibroin hydrogel provides an effective strategy for the treatment of RA and other autoimmune diseases.

Antifibrotic Effects of Tetrahedral Framework Nucleic Acids by Inhibiting Macrophage Polarization and Macrophage-Myofibroblast Transition in Bladder Remodeling

Bladder outlet obstruction (BOO) is a prevalent condition arising from urethral stricture, posterior urethral valves, and benign prostatic hyperplasia. Long-term obstruction can lead to bladder remodeling, which is characterized by inflammatory cell infiltration, detrusor hypertrophy, and fibrosis. Until now, there are no efficacious therapeutic options for BOO-induced remodeling. Tetrahedral framework nucleic acids (tFNAs) are a type of novel 3D DNA nanomaterials that possess excellent antifibrotic effects. Here, to determine the treatment effects of tFNAs on BOO-induced remodeling is aimed. Four single-strand DNAs are self-assembled to form tetrahedral framework DNA nanostructures, and the antifibrotic effects of tFNAs are investigated in an in vivo BOO animal model and an in vitro transforming growth factor beta1 (TGF-β1)-induced fibrosis model. The results demonstrated that tFNAs could ameliorate BOO-induced bladder fibrosis and dysfunction by inhibiting M2 macrophage polarization and the macrophage-myofibroblast transition (MMT) process. Furthermore, tFNAs regulate M2 polarization and the MMT process by deactivating the signal transducer and activator of transcription (Stat) and TGF-β1/small mothers against decapentaplegic (Smad) pathways, respectively. This is the first study to reveal that tFNAs might be a promising nanomaterial for the treatment of BOO-induced remodeling.

Advances in regenerative medicine applications of tetrahedral framework nucleic acid-based nanomaterials: an expert consensus recommendation

With the emergence of DNA nanotechnology in the 1980s, self-assembled DNA nanostructures have attracted considerable attention worldwide due to their inherent biocompatibility, unsurpassed programmability, and versatile functions. Especially promising nanostructures are tetrahedral framework nucleic acids (tFNAs), first proposed by Turberfield with the use of a one-step annealing approach. Benefiting from their various merits, such as simple synthesis, high reproducibility, structural stability, cellular internalization, tissue permeability, and editable functionality, tFNAs have been widely applied in the biomedical field as three-dimensional DNA nanomaterials. Surprisingly, tFNAs exhibit positive effects on cellular biological behaviors and tissue regeneration, which may be used to treat inflammatory and degenerative diseases. According to their intended application and carrying capacity, tFNAs could carry functional nucleic acids or therapeutic molecules through extended sequences, sticky-end hybridization, intercalation, and encapsulation based on the Watson and Crick principle. Additionally, dynamic tFNAs also have potential applications in controlled and targeted therapies. This review summarized the latest progress in pure/modified/dynamic tFNAs and demonstrated their regenerative medicine applications. These applications include promoting the regeneration of the bone, cartilage, nerve, skin, vasculature, or muscle and treating diseases such as bone defects, neurological disorders, joint-related inflammatory diseases, periodontitis, and immune diseases.

A Mini-Review of Diagnostic and Therapeutic Nano-Tools for Pancreatitis

Pancreatitis is an inflammatory reaction of pancreatic tissue digestion, edema, bleeding and even necrosis caused by activation of pancreatin due to various causes. In particular, patients with severe acute pancreatitis (SAP) often suffer from secondary infection, peritonitis and shock, and have a high mortality rate. Chronic pancreatitis (CP) can cause permanent damage to the pancreas. Due to the innate characteristics, structure and location of the pancreas, there is no effective treatment, only relief of symptoms. Especially, AP is an unpredictable and potentially fatal disease, and the timely diagnosis and treatment remains a major challenge. With the rapid development of nanomedicine technology, many potential tools can be used to address this problem. In this review, we have introduced the pathophysiological processes of pancreatitis to understanding its etiology and severity. Most importantly, the current progress in the diagnosis and treatment tools of pancreatitis based on nanomedicine is summarized and prospected.

Effect of Tetrahedral Framework Nucleic Acids on Neurological Recovery via Ameliorating Apoptosis and Regulating the Activation and Polarization of Astrocytes in Ischemic Stroke

Astrocytes, as the most plentiful subtypes of glial cells, play an essential biphasic function in ischemic stroke (IS). However, although having beneficial effects on stroke via promoting nerve restoration and limiting lesion extension, astrocytes can unavoidably cause exacerbated brain damage due to their participation in the inflammatory response. Therefore, seeking an effective and safe drug/strategy for protecting and regulating astrocytes in stroke is urgent. Here, we employ tetrahedral framework nucleic acid (tFNA) nanomaterials for astrocytes in stroke, considering their excellent biological properties and outstanding biosafety. In vitro, tFNA can inhibit calcium overload and ROS regeneration triggered by oxygen-glucose deprivation/reoxygenation (OGD/R), which provides a protective effect against astrocytic apoptosis. Furthermore, morphological changes such as hyperplasia and hypertrophy of reactive astrocytes are restrained, and the astrocytic polarization from the proinflammatory A1 phenotype to the neuroprotective A2 phenotype is facilitated by tFNA, which further alleviates cerebral infarct volume and facilitates the recovery of neurological function in transient middle cerebral artery occlusion (tMCAo) rat models. Moreover, the TLRs/NF-κB signaling pathway is downregulated by tFNA, which may be the potential mechanism of tFNA for protecting astrocytes in stroke. Collectively, we demonstrate that tFNA can effectively mediate astrocytic apoptosis, activation, and polarization to alleviate brain injury, which represents a potential intervention strategy for IS.

Tetrahedral Framework Nucleic Acids Inhibit Skin Fibrosis via the Pyroptosis Pathway

The skin is the first line of defense for the human body and is vulnerable to injury. Various topical or systemic diseases facilitate skin inflammation, and when the intensity or duration of skin injury exceeds the ability of tissue repair, fibrosis, an outcome of a dysregulated tissue-repair response, begins to dominate the repair process. However, existing methods for reducing skin fibrosis are insufficient and cause side effects, highlighting the need for drugs that effectively inhibit skin fibrosis and reduce immunogenicity, inflammation, apoptosis, and pyroptosis. Tetrahedral framework nucleic acids (tFNAs) are DNA nanomaterials that have a unique spatial structure, demonstrate excellent biosecurity, and promote anti-inflammatory, antioxidative, antifibrotic, angiogenic, and skin-wound-healing activities with almost no toxicity. Here, we explored the potential of tFNAs in skin fibrosis therapy in vitro and in vivo. After incubating cells or injecting mice with profibrogenic molecules and tFNAs, we found that the tFNAs inhibited the epithelial-mesenchymal transition, reduced inflammatory factor levels, decreased skin collagen content, and inhibited the pyroptosis pathway. These findings suggest the potential of tFNAs in treating pyroptosis-related diseases.

Tetrahedral Framework Nucleic Acids Can Alleviate Taurocholate-Induced Severe Acute Pancreatitis and Its Subsequent Multiorgan Injury in Mice

Severe acute pancreatitis (SAP) is an inflammatory disease of the pancreas accompanied by tissue injury and necrosis. It not only affects the pancreas but also triggers a systemic inflammatory response that leads to multiorgan failure or even death. Moreover, there is no effective treatment currently that can reverse the disease progression. In this study, tetrahedral framework nucleic acids (tFNAs) were utilized to treat SAP in mice for the first time and proved to be effective in suppressing inflammation and preventing pathological cell death. Serum levels of pancreatitis-related biomarkers witnessed significant changes after tFNAs treatment. Reduction in the expression of certain cytokines involved in local and systemic inflammatory response were observed, together with alteration in proteins related to cell death and apoptosis. Collectively, our results demonstrate that tFNAs could both alleviate SAP and its subsequent multiorgan injury in mice, thus offering a novel and effective option to deal with SAP in the future.

Tetrahedral Framework Nucleic Acids Reverse New-Onset Type 1 Diabetes

Type 1 diabetes (T1D) is caused by breakdowns of central and peripheral immune tolerance and destructions of insulin-producing β-cells. Conventional insulin injection cannot cure the disease. Regulatory immune cells, including regulatory T-cells (Tregs) and regulatory B-cells (Bregs), play critical roles in immune tolerance. Inducing regulatory immune cells to halt the progress of T1D and restore immune tolerance is the promising approach in T1D immunotherapy. Here, tetrahedral framework nucleic acids (tFNAs) were utilized to treat T1D in non-obese diabetic (NOD) mice. 250 nM tFNA treatment was adopted in the experiment to reverse hyperglycemia and protect insulin-secreting β-cells in diabetic NOD mice. In addition, 250 nM tFNA treatment could induce Tregs and Bregs and suppress helper T (Th)-cells in the pancreas. In the pancreas, cytokines, as a significant signal during CD4⁺ T-cell differentiation, directly direct the differentiation programs. Apart from cytokines directing the differentiation of T-cells, the signal transducer and activator of transcription (STAT) signal is strongly associated with T-cell differentiation and T1D progression. We demonstrated tFNA treatment inducing regulatory immune cells probably by increasing TGF-β levels and the STAT signal. To sum up, 250 nM tFNA treatment could protect the diabetic NOD mice from hyperglycemia and preserve the functions of β-cells by restoring peripheral immune tolerance. The possible mechanism of inducing immune tolerance was related to the STAT signal and cytokine changes in the pancreas. Moreover, immunoregulation capabilities of tFNAs were demonstrated in the experiment, which set the foundation of tFNAs participating in further antigen-specific immunotherapies.