An mTOR siRNA-Loaded Spermidine/DNA Tetrahedron Nanoplatform with a Synergistic Anti-Inflammatory Effect on Acute Lung Injury

Nano-Proteolysis Targeting Chimeras (Nano-PROTACs) in Cancer Therapy

Proteolysis-targeting chimeras (PROTACs) are heterobifunctional molecules that have the capability to induce specific protein degradation. While playing a revolutionary role in effectively degrading the protein of interest (POI), PROTACs encounter certain limitations that impede their clinical translation. These limitations encompass off-target effects, inadequate cell membrane permeability, and the hook effect. The advent of nanotechnology presents a promising avenue to surmount the challenges associated with conventional PROTACs. The utilization of nano-proteolysis targeting chimeras (nano-PROTACs) holds the potential to enhance specific tissue accumulation, augment membrane permeability, and enable controlled release. Consequently, this approach has the capacity to significantly enhance the controllable degradation of target proteins. Additionally, they enable a synergistic effect by combining with other therapeutic strategies. This review comprehensively summarizes the structural basis, advantages, and limitations of PROTACs. Furthermore, it highlights the latest advancements in nanosystems engineered for delivering PROTACs, as well as the development of nano-sized PROTACs employing nanocarriers as linkers. Moreover, it delves into the underlying principles of nanotechnology tailored specifically for PROTACs, alongside the current prospects of clinical research. In conclusion, the integration of nanotechnology into PROTACs harbors vast potential in enhancing the anti-tumor treatment response and expediting clinical translation.

Spermidine-Functionalized Injectable Hydrogel Reduces Inflammation and Enhances Healing of Acute and Diabetic Wounds In Situ

The inflammatory response is a key factor affecting tissue regeneration. Inspired by the immunomodulatory role of spermidine, an injectable double network hydrogel functionalized with spermidine (DN-SPD) is developed, where the first and second networks are formed by dynamic imine bonds and non-dynamic photo-crosslinked bonds respectively. The single network hydrogel before photo-crosslinking exhibits excellent injectability and thus can be printed and photo-crosslinked in situ to form double network hydrogels. DN-SPD hydrogel has demonstrated desirable mechanical properties and tissue adhesion. More importantly, an "operando" comparison of hydrogels loaded with spermidine or diethylenetriamine (DETA), a sham molecule resembling spermidine, has shown similar physical properties, but quite different biological functions. Specifically, the outcomes of 3 sets of in vivo animal experiments demonstrate that DN-SPD hydrogel can not only reduce inflammation caused by implanted exogenous biomaterials and reactive oxygen species but also promote the polarization of macrophages toward regenerative M2 phenotype, in comparison with DN-DETA hydrogel. Moreover, the immunoregulation by spermidine can also translate into faster and more natural healing of both acute wounds and diabetic wounds. Hence, the local administration of spermidine affords a simple but elegant approach to attenuate foreign body reactions induced by exogenous biomaterials to treat chronic refractory wounds.

Macrophage-Targeting DNA Nanomaterials: A Future Direction of Biological Therapy

DNA can be used for precise construction of complex and flexible micro-nanostructures, including DNA origami, frame nucleic acids, and DNA hydrogels. DNA nanomaterials have good biocompatibility and can enter macrophages via scavenger receptor-mediated endocytosis. DNA nanomaterials can be uniquely and flexibly designed to ensure efficient uptake by macrophages, which represents a novel strategy to regulate macrophage function. With the development of nanotechnology, major advances have been made in the design and manufacturing of DNA nanomaterials for clinical therapy. In diseases accompanied by macrophage disturbances including tumor, infectious diseases, arthritis, fibrosis, acute lung injury, and atherosclerosis, DNA nanomaterials received considerable attention as potential treatments. However, we lack sufficient information to guarantee precise targeting of macrophages by DNA nanomaterials, which precludes their therapeutic applications. In this review, we summarize recent studies of macrophage-targeting DNA nanomaterials and discuss the limitations and challenges of this approach with regard to its potential use as a biological therapy.

Autophagy-modulating biomaterials: multifunctional weapons to promote tissue regeneration

Autophagy is a self-renewal mechanism that maintains homeostasis and can promote tissue regeneration by regulating inflammation, reducing oxidative stress and promoting cell differentiation. The interaction between biomaterials and tissue cells significantly affects biomaterial-tissue integration and tissue regeneration. In recent years, it has been found that biomaterials can affect various processes related to tissue regeneration by regulating autophagy. The utilization of biomaterials in a controlled environment has become a prominent approach for enhancing the tissue regeneration capabilities. This involves the regulation of autophagy in diverse cell types implicated in tissue regeneration, encompassing the modulation of inflammatory responses, oxidative stress, cell differentiation, proliferation, migration, apoptosis, and extracellular matrix formation. In addition, biomaterials possess the potential to serve as carriers for drug delivery, enabling the regulation of autophagy by either activating or inhibiting its processes. This review summarizes the relationship between autophagy and tissue regeneration and discusses the role of biomaterial-based autophagy in tissue regeneration. In addition, recent advanced technologies used to design autophagy-modulating biomaterials are summarized, and rational design of biomaterials for providing controlled autophagy regulation via modification of the chemistry and surface of biomaterials and incorporation of cells and molecules is discussed. A better understanding of biomaterial-based autophagy and tissue regeneration, as well as the underlying molecular mechanisms, may lead to new possibilities for promoting tissue regeneration. Video Abstract.

Intratracheal administration of programmable DNA nanostructures combats acute lung injury by targeting microRNA-155

Acute lung injury (ALI) is an acute inflammatory process that can result in life-threatening consequences. Programmable DNA nanostructures have emerged as excellent nanoplatforms for microRNA-based therapeutics, offering potential nanomedicines for ALI treatment. Nonetheless, the traditional systematic administration of nanomedicines is constrained by low delivery efficiency, poor pharmacokinetics, and nonspecific side effects. Here, we identify macrophage microRNA-155 as a novel therapeutic target using the magnetic bead sorting technique. We further construct a DNA nanotubular nucleic acid drug antagonizing microRNA-155 (NT-155) for ALI treatment through intratracheal administration. Flow cytometry results demonstrate that NT-155, when inhaled, is taken up much more effectively by macrophages and dendritic cells in the bronchoalveolar lavage fluid of ALI mice. Furthermore, NT-155 effectively silences the overexpressed microRNA-155 in macrophages and exerts excellent inflammation inhibition effects in vitro and ALI mouse models. Mechanistically, NT-155 suppresses microRNA-155 expression and activates its target gene SOCS1, inhibiting the p-P65 signaling pathway and suppressing proinflammatory cytokine secretion. The current study suggests that deliberately designed nucleic acid drugs are promising nanomedicines for ALI treatment and the local administration may open up new practical applications of DNA in the future.

Counteracting Immunosenescence-Which Therapeutic Strategies Are Promising?

Aging attenuates the overall responsiveness of the immune system to eradicate pathogens. The increased production of pro-inflammatory cytokines by innate immune cells under basal conditions, termed inflammaging, contributes to impaired innate immune responsiveness towards pathogen-mediated stimulation and limits antigen-presenting activity. Adaptive immune responses are attenuated as well due to lowered numbers of naïve lymphocytes and their impaired responsiveness towards antigen-specific stimulation. Additionally, the numbers of immunoregulatory cell types, comprising regulatory T cells and myeloid-derived suppressor cells, that inhibit the activity of innate and adaptive immune cells are elevated. This review aims to summarize our knowledge on the cellular and molecular causes of immunosenescence while also taking into account senescence effects that constitute immune evasion mechanisms in the case of chronic viral infections and cancer. For tumor therapy numerous nanoformulated drugs have been developed to overcome poor solubility of compounds and to enable cell-directed delivery in order to restore immune functions, e.g., by addressing dysregulated signaling pathways. Further, nanovaccines which efficiently address antigen-presenting cells to mount sustained anti-tumor immune responses have been clinically evaluated. Further, senolytics that selectively deplete senescent cells are being tested in a number of clinical trials. Here we discuss the potential use of such drugs to improve anti-aging therapy.

Nucleic acid-based artificial nanocarriers for gene therapy

Nucleic acid nanotechnology is a powerful tool in the fields of biosensing and nanomedicine owing to their high editability and easy synthesis and modification. Artificial nucleic acid nanostructures have become an emerging research hotspot as gene carriers with low cytotoxicity and immunogenicity for therapeutic approaches. In this review, recent progress in the design and functional mechanisms of nucleic acid-based artificial nano-vectors especially for exogenous siRNA and antisense oligonucleotide delivery is summarized. Different types of DNA nanocarriers, including DNA junctions, tetrahedrons, origami, hydrogels and scaffolds, are introduced. The enhanced targeting strategies to improve the delivery efficacy are demonstrated. Furthermore, RNA based gene nanocarrier systems by self-assembly of short strands, rolling circle transcription, chemical crosslinking and using RNA motifs and DNA-RNA hybrids are demonstrated. Finally, the outlook and potential challenges are highlighted. The nucleic acid-based artificial nanocarriers offer a promising and precise tool for gene delivery and therapy.

A bivalent aptamer and terminus-free siRNA junction nanostructure for targeted gene silencing in cancer cells

Small interfering RNA (siRNA) has increasingly evolved as a potent therapeutic solution for several pathological conditions including cancers via post-transcriptional oncogene suppression in cellular pathways. And, the key for siRNA-based therapy highly relies on the successful siRNAs delivery into the target cells, which is significantly challenged by their instability, poor cellular uptake and targeting capability. To overcome these issues, herein, a new type of RNA nanostructure, the bivalent aptamer and terminus-free siRNA junction, is synthesized and employed for effective gene silencing in cancer cells. Such a siRNA junction can be readily prepared by the self-assembly of three RNA sequences and subsequent ligation of the nicks. The as-synthesized siRNA junction shows highly improved enzymatic stability and targeting capability and can be efficiently delivered into the target cells to induce cell apoptosis. With these integrated advantages, the siRNA junction can therefore offer new potentials for the design of different siRNA therapeutics for various diseases.