Pancreatic cancer, predominantly pancreatic ductal adenocarcinoma (PDAC), remains a highly lethal malignancy with limited therapeutic options and a dismal prognosis. By targeting the underlying molecular abnormalities responsible for PDAC development and progression, gene therapy offers a promising strategy to overcome the challenges posed by conventional radiotherapy and chemotherapy. This study sought to explore the therapeutic potential of small activating RNAs (saRNAs) specifically targeting the CCAAT/enhancer-binding protein alpha (CEBPA) gene in PDAC. To overcome the challenges associated with saRNA delivery, tetrahedral framework nucleic acids (tFNAs) were rationally engineered as nanocarriers. These tFNAs were further functionalized with a truncated transferrin receptor aptamer (tTR14) to enhance targeting specificity for PDAC cells. The constructed tFNA-based saRNA formulation demonstrated exceptional stability, efficient saRNA release ability, substantial cellular uptake, biocompatibility, and nontoxicity. In vitro experiments revealed successful intracellular delivery of CEBPA-saRNA utilizing tTR14-decorated tFNA nanocarriers, resulting in significant activation of tumor suppressor genes, namely, CEBPA and its downstream effector P21, leading to notable inhibition of PDAC cell proliferation. Moreover, in a mouse model of PDAC, the tTR14-decorated tFNA-mediated delivery of CEBPA-saRNA effectively upregulated the expression of the CEBPA and P21 genes, consequently suppressing tumor growth. These compelling findings highlight the potential utility of saRNA delivered via a designed tFNA nanocarrier to induce the activation of tumor suppressor genes as an innovative therapeutic approach for PDAC.

Choroidal neovascularization (CNV) is a common pathological feature of various eye diseases and an important cause of visual impairment in middle-aged and elderly patients. In previous studies, tetrahedral framework nucleic acids (tFNAs) showed good carrier performance. In this experiment, we developed microRNA-155-equipped tFNAs (T-155) and explored its biological effects on CNV. Based on the results of in-vitro experiments, T-155 could regulate macrophages into the antiangiogenic M1 type. Then, we injected T-155 into the vitreous of laser-induced CNV model mice and found that T-155 significantly reduced the size and area of CNV, inhibited blood vessel leakage. In summary, we prove that T-155 could regulate the inflammatory process of CNV by polarizing macrophages, thereby improving the symptoms of CNV. Thus, T-155 might become a new DNA-based drug with great potential for treating CNV.

Tetrahedral framework nucleic acid (tFNA), a special DNA nanodevice, is widely applied in diverse biomedical fields. Due to its high programmability, biocompatibility, tissue permeability as well as its capacity for cell proliferation and differentiation, tFNA presents a powerful tool that could overcome potential barriers in the treatment of neurological disorders. This review evaluates recent studies on the use and progress of tFNA-based nanomaterials in neurological disorders.

OBJECTIVE: Autoimmune diseases are a heterogeneous group of diseases which lose the immunological tolerance to self-antigens. It is well recognized that irregularly provoked T cells participate in the pathological immune responses. As a novel nanomaterial with promising applications, tetrahedral framework nucleic acid (TFNA) nanostructure was found to have immune regulatory effects on T cells in this study.
METHODS: To verify the successful fabrication of TFNA, the morphology of TFNA was observed by atomic force microscopy (AFM) and dynamic light scattering. The regulatory effect of TFNA was evaluated by flow cytometry after cocultured with CD3+ T cells isolated from healthy donors. Moreover, the associated signaling pathways were investigated. Finally, we verified our results on the T cells from patients with neuromyelitis optica spectrum disorder (NMOSD), which is a typical autoimmune disease induced by T cells.
RESULTS: We revealed the alternative regulatory functions of TFNA in human primary T cells with steady status via the JNK signaling pathway. Moreover, by inhibiting both JNK and ERK phosphorylation, TFNA exhibited significant suppressive effects on IFNγ secretion from provoking T cells without affecting TNF secretion. Similar immune regulatory effects of TFNA were also observed in autoreactive T cells from patients with NMOSD.
CONCLUSIONS: Overall, our results revealed a potential application of TFNA in regulating the adaptive immune system, as well as shed a light on the treatment of T cell-mediated autoimmune diseases.

Obesity-induced insulin resistance is the hallmark of metabolic syndrome, and chronic, low-grade tissue inflammation links obesity to insulin resistance through the activation of tissue-infiltrating immune cells. Current therapeutic approaches lack efficacy and immunomodulatory capacity. Thus, a new therapeutic approach is needed to prevent chronic inflammation and alleviate insulin resistance. Here, we synthesized a tetrahedral framework nucleic acid (tFNA) nanoparticle that carried resveratrol (RSV) to inhibit tissue inflammation and improve insulin sensitivity in obese mice. The prepared nanoparticles, namely tFNAs-RSV, possessed the characteristics of simple synthesis, stable properties, good water solubility, and superior biocompatibility. The tFNA-based delivery ameliorated the lability of RSV and enhanced its therapeutic efficacy. In high-fat diet (HFD)-fed mice, the administration of tFNAs-RSV ameliorated insulin resistance by alleviating inflammation status. tFNAs-RSV could reverse M1 phenotype macrophages in tissues to M2 phenotype macrophages. As for adaptive immunity, the prepared nanoparticles could repress the activation of Th1 and Th17 and promote Th2 and Treg, leading to the alleviation of insulin resistance. Furthermore, this study is the first to demonstrate that tFNAs, a nucleic acid material, possess immunomodulatory capacity. Collectively, our findings demonstrate that tFNAs-RSV alleviate insulin resistance and ameliorate inflammation in HFD mice, suggesting that nucleic acid materials or nucleic acid-based delivery systems may be a potential agent for the treatment of insulin resistance and obesity-related metabolic diseases.

In a search for a solution to large-area soft and hard tissue defects, whether or not tissue regeneration or tissue-substitutes transplantation is used, the problems with angiogenesis need to be solved urgently. Thus, a new and efficient proangiogenic approach is needed. Nanoengineering systems have been considered one of the most promising approaches. In this study, we modify the tetrahedral framework nucleic acid (tFNA) for the first time with two different angiogenic DNA aptamers to form aptamer-tFNA nanostructures, tFNA-Apt02 and tFNA-AptVEGF, and the effects of them on angiogenesis both in vitro and in vivo are investigated. We develop new nanomaterials for enhancing angiogenesis to solve the problem of tissue engineering vascularization and ischemic diseases. The results of our study confirm that tFNA-Apt02 and tFNA-AptVEGF has a stronger ability to accelerate endothelial cell proliferation and migration, tubule formation, spheroid sprouting, and angiogenesis in vivo. We first demonstrate that the engineered novel tFNA-Apt02 and tFNA-AptVEGF have promoting effects on angiogenesis both in vitro and in vivo and provide a theoretical basis and opportunity for their application in tissues engineering vascularization and ischemic diseases.

Poor penetrability and nonselective distribution of chemotherapeutic drugs are the main obstacles for chemotherapy for triple-negative breast cancer (TNBC). In our work, we developed a DNA-based drug delivery system to surmount these barriers. In addition, a tetrahedral framework nucleic acid (tFNA) was employed to load doxorubicin (DOX) with iRGD decoration to form a novel nanoparticle (tFNA/DOX@iRGD). The RGD sequence and the CendR motif in iRGD are used in tumor targeting and tissue penetration, respectively. Based on the sustained serum stability and pH-sensitive release behavior of DOX, tFNA/DOX@iRGD exhibited superiority for biomedical application. Moreover, tFNA/DOX@iRGD showed excellent deep penetration and drug accumulation in three-dimensional (3D) multicellular tumor spheroids compared to DOX and tFNA/DOX. Additionally, the therapeutic effect was verified in a 4T1 subcutaneous tumor model, and the complexes displayed a superior antitumor and antiangiogenic efficiency with fewer collateral damages. Therefore, these findings suggested that tFNA/DOX@iRGD might be a more effective pattern for drug delivery and TNBC therapy.

Osteoarthritis (OA) is a degenerative articular cartilage pathogenic process that is accompanied by excessive chondrocyte apoptosis. The occurrence of chondrocyte death and OA is related to decreased autophagy. Tetrahedral framework nucleic acid (TFNA), a potent bioactive DNA nanomaterial, exerts antiapoptotic and antioxidative effects in various diseases, resulting in autophagy promotion and inhibition of the Wnt/β-catenin-signaling pathway. Here, we aimed to elucidate the therapeutic effects of TFNA on OA and its potential molecular mechanism of action. TFNA was synthesized and characterized by established methods. An interleukin (IL)-1β stimulated OA cell model was established and treated with TFNA. Cellular uptake of TFNA and intracellular reactive oxygen species levels were examined via immunofluorescence and flow cytometry. Apoptotic cell death was documented by the Cell Counting Kit-8 (CCK8) assay and flow cytometry. Transmission electron microscopy was applied to view the autophagosomes. The expression of BCL2, BAX, caspase-3, Nrf2, HO-1, LC3-II, Beclin1, Atg7, β-catenin, Lef-1, and CyclinD1 was detected by immunofluorescence and western blotting. TFNA was successfully synthesized and effectively entered chondrocytes in the absence or presence of IL-1β without the help of transfection agents. TFNA treatment in IL-1β-induced chondrocytes reduced apoptosis by activating the BCL2/BAX/caspase-3 pathway, inhibited oxidative stress by regulating the Nrf2/HO-1-signaling pathway, and enhanced autophagy through upregulated LC3-II, Beclin1, and Atg7. Moreover, TFNA showed chondroprotective effects by regulating the Wnt/β-catenin-signaling pathway. Overall, TFNA may have utility as a therapeutic nanomedicine for OA.

The past decades have witnessed the development of DNA nanotechnology and the emergence of various spatial DNA nanostructures, from two-dimensions to three-dimensions. The typical example is the tetrahedral framework nucleic acid (tFNA). In this review, we summarize the progress in fabrication, modification of tFNA-based functional systems and their potentials in biomedical applications. Through a one-step assembly process, tFNA is synthesized via four single stranded DNAs with three short sequences complementary to the other sequence of another single strand. Characterizations including polyacrylamide gel electrophoresis, atomic force microscopy, and dynamic light scattering measurement show tFNA as a pyramid-like nanostructure with the size of around 10 nm. Feathered with intrinsic biocompatibility and satisfactory cellular membrane permeability, the first generation of tFNA shows promising capacities in regulating cell biological behavior, promoting tissue regeneration, and immunomodulation. Along with excellent editability and relative biostability in complicated conditions, tFNA could be modified via hanging functional domains on the vertex or side arm and incorporating small-molecular-weight drugs to form the second generation, for reversing multidrug resistance in tumor cells or microorganisms, target therapy, anticancer and antibacterial treatments. The third generation of tFNA is currently tried via a multistep assembly process for stimuli-response and precise drug release. Although tFNAs show promising potentials in cargo delivery, massive efforts still need to be made to improve biostability, maximal load, and structural controllability.

Bisphosphonates are often used to treat osteoporosis, malignant bone metastases, and hypercalcemia. However, it can cause serious adverse reactions, bisphosphonate-related osteonecrosis of the jaw (BRONJ), which seriously affects the quality of life of patients. At present, the treatment of BRONJ is still difficult to reach an agreement, and there is no effective treatment. Therefore, it is very important to find effective treatments. Many studies have shown that the occurrence of BRONJ may be due to unbalanced bone turnover, anti-angiogenesis, bacterial infection, direct tissue toxicity, and abnormal immune function. The previous research results show that tetrahedral framework nucleic acids (tFNAs), a new type of nanomaterial, can promote various biological activities of cells, such as cell proliferation, migration, anti-inflammation and anti-oxidation, and angiogenesis. Therefore, we intend to explore the potential of tFNAs in the treatment of BRONJ through this study. The results show that tFNAs can promote the treatment of BRONJ by promoting angiogenesis and promoting M2 polarization in macrophages and inhibiting M1 polarization both in vitro and in vivo. These results provide a theoretical basis for the application of tFNAs in the treatment of BRONJ and also provide new ideas and methods for the treatment of other diseases based on ischemia and immune disorders.