Supramolecular self-assembled nanoparticles mediate oral delivery of therapeutic TNF-α siRNA against systemic inflammation

Targeted delivery methods for RNA interference are necessary to obtain a potential functional cure for HIV/AIDS

Ribonucleic acid (RNA) is of great interest in many different therapeutic areas including infectious diseases such as immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). Thanks to current, advanced treatments for HIV, the diagnosis is no longer a death sentence. However, even with these treatments, latency is suggested to persist in T-lymphocyte-rich tissues including gut-associated lymphatic tissue (GALT), spleen, and bone marrow making HIV an incurable disease. Therefore, it is important to design systems that can effectively deliver therapeutics to these tissues to fight latent infection and find a functional cure. Numerous therapeutics ranging from small molecules to cell therapies have been explored as a cure for HIV but have failed to maintain therapeutic longevity. RNA interference (RNAi) provides a unique opportunity to achieve a functional cure for those who suffer from chronic HIV/AIDS by suppressing replication of the virus. However, RNA has certain imitations in delivery as it cannot be delivered without a carrier due to its negative charge and degradation from endogenous nucleases. Here, we provide a detailed analysis of explored systems for siRNA delivery for HIV/AIDS in the context of RNA therapeutic design and nanoparticle design. In addition, we suggest strategies that should be used to target specific tissues that are rich in lymphatic tissue.

Oral Delivery of siRNA Using Fluorinated, Small-Sized Nanocapsules toward Anti-Inflammation Treatment

Oral delivery of small interfering RNA (siRNA) provides a promising paradigm for treating diseases that require regular injections. However, the multiple gastrointestinal (GI) and systemic barriers often lead to inefficient oral absorption and low bioavailability of siRNA. Technologies that can overcome these barriers are still lacking, which hinders the clinical potential of orally delivered siRNA. Herein, small-sized, fluorinated nanocapsules (F-NCs) are developed to mediate efficient oral delivery of tumor necrosis factor α (TNF-α) siRNA for anti-inflammation treatment. The NCs possess a disulfide-cross-linked shell structure, thus featuring robust stability in the GI tract. Because of their small size (≈30 nm) and fluorocarbon-assisted repelling of mucin adsorption, the best-performing F₃ -NCs show excellent mucus penetration and intestinal transport capabilities without impairing the intestinal tight junction, conferring the oral bioavailability of 20.4% in relative to intravenous injection. The disulfide cross-linker can be cleaved inside target cells, causing NCs dissociation and siRNA release to potentiate the TNF-α silencing efficiency. In murine models of acute and chronic inflammation, orally delivered F₃ -NCs provoke efficient TNF-α silencing and pronounced anti-inflammatory efficacies. This study therefore provides a transformative strategy for oral siRNA delivery, and will render promising utilities for anti-inflammation treatment.

Multifunctional hydrogels based on chitosan, hyaluronic acid and other biological macromolecules for the treatment of inflammatory bowel disease: A review

Hydrogel is a three-dimensional network polymer material rich in water. It is widely used in the biomedical field because of its unique physical and chemical properties and good biocompatibility. In recent years, the incidence of inflammatory bowel disease (IBD) has gradually increased, and the disadvantages caused by traditional drug treatment of IBD have emerged. Therefore, there is an urgent need for new treatments to alleviate IBD. Hydrogel has become a potential therapeutic platform. However, there is a lack of comprehensive review of functional hydrogels for IBD treatment. This paper first summarizes the pathological changes in IBD sites. Then, the action mechanisms of hydrogels prepared from chitosan, sodium alginate, hyaluronic acid, functionalized polyethylene glycol, cellulose, pectin, and γ-polyglutamic acid on IBD were described from aspects of drug delivery, peptide and protein delivery, biologic therapies, loading probiotics, etc. In addition, the advanced functions of IBD treatment hydrogels were summarized, with emphasis on adhesion, synergistic therapy, pH sensitivity, particle size, and temperature sensitivity. Finally, the future development direction of IBD treatment hydrogels has been prospected.

Oral Delivery of Nucleic Acid Therapies for Local and Systemic Action

Nucleic acid (NA) therapy has gained importance over the past decade due to its high degree of selectivity and minimal toxic effects over conventional drugs. Currently, intravenous (IV) or intramuscular (IM) formulations constitute majority of the marketed formulations containing nucleic acids. However, oral administration is traditionally preferred due to ease of administration as well as higher patient compliance. To leverage the benefits of oral delivery for NA therapy, the NA of interest must be delivered to the target site avoiding all degrading and inhibiting factors during its transition through the gastrointestinal tract. The oral route presents myriad of challenges to NA delivery, making formulation development challenging. Researchers in the last few decades have formulated various delivery systems to overcome such challenges and several reviews summarize and discuss these strategies in detail. However, there is a need to differentiate between the approaches based on target so that in future, delivery strategies can be developed according to the goal of the study and for efficient delivery to the desired site. The goal of this review is to summarize the mechanisms for target specific delivery, list and discuss the formulation strategies used for oral delivery of NA therapies and delineate the similarities and differences between local and systemic targeting oral delivery systems and current challenges.

Nanoparticles-mediated CRISPR-Cas9 gene therapy in inherited retinal diseases: applications, challenges, and emerging opportunities

Inherited Retinal Diseases (IRDs) are considered one of the leading causes of blindness worldwide. However, the majority of them still lack a safe and effective treatment due to their complexity and genetic heterogeneity. Recently, gene therapy is gaining importance as an efficient strategy to address IRDs which were previously considered incurable. The development of the clustered regularly-interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) system has strongly empowered the field of gene therapy. However, successful gene modifications rely on the efficient delivery of CRISPR-Cas9 components into the complex three-dimensional (3D) architecture of the human retinal tissue. Intriguing findings in the field of nanoparticles (NPs) meet all the criteria required for CRISPR-Cas9 delivery and have made a great contribution toward its therapeutic applications. In addition, exploiting induced pluripotent stem cell (iPSC) technology and in vitro 3D retinal organoids paved the way for prospective clinical trials of the CRISPR-Cas9 system in treating IRDs. This review highlights important advances in NP-based gene therapy, the CRISPR-Cas9 system, and iPSC-derived retinal organoids with a focus on IRDs. Collectively, these studies establish a multidisciplinary approach by integrating nanomedicine and stem cell technologies and demonstrate the utility of retina organoids in developing effective therapies for IRDs.

A Lysosome-Activated Tetrahedral Nanobox for Encapsulated siRNA Delivery

Tetrahedral framework nucleic acids (tFNAs) have attracted extensive attention as drug nanocarriers because of their excellent cellular uptake. However, for oligonucleotide cargos, tFNA mainly acts as a static delivery platform generated via sticky-ended ligation. Here, inspired by the original stable space inside the tetrahedral scaffold, a dynamic lysosome-activated tFNA nanobox is fabricated for completely encapsulating a short interfering RNA (siRNA) of interest. The closed tetrahedral structure endows cargo siRNA with greater resistance against RNase and serum and enables solid integration with the vehicle during delivery. Moreover, the pH-responsive switch of nanobox allows the controlled release of siRNA upon entry into lysosomes at cell culture temperature. Based on protective loading and active unloading, an excellent silencing effect on the target tumor necrosis factor alpha (TNFα) gene is achieved in in vitro and in vivo experiments. Conclusively, the nanobox offers a dynamic pH-sensitive confinement delivery system for siRNA and can be an extendable strategy for other small RNA.

Advances in oral peptide drug nanoparticles for diabetes mellitus treatment

Peptide drugs play an important role in diabetes mellitus treatment. Oral administration of peptide drugs is a promising strategy for diabetes mellitus because of its convenience and high patient compliance compared to parenteral administration routes. However, there are a series of formidable unfavorable conditions present in the gastrointestinal (GI) tract after oral administration, which result in the low oral bioavailability of these peptide drugs. To overcome these challenges, various nanoparticles (NPs) have been developed to improve the oral absorption of peptide drugs due to their unique in vivo properties and high design flexibility. This review discusses the unfavorable conditions present in the GI tract and provides the corresponding strategies to overcome these challenges. The review provides a comprehensive overview on the NPs that have been constructed for oral peptide drug delivery in diabetes mellitus treatment. Finally, we will discuss the rational application and give some suggestions that can be utilized for the development of oral peptide drug NPs. Our aim is to provide a systemic and comprehensive review of oral peptide drug NPs that can overcome the challenges in GI tract for efficient treatment of diabetes mellitus.

•Oral administration of peptide drugs is a promising strategy for diabetes mellitus treatment

•A series of formidable unfavorable conditions in gastrointestinal tract result in the low oral bioavailability of peptide drugs

•Nanoparticles can improve the oral bioavailability of peptide drugs

Targeting the Gut Mucosal Immune System Using Nanomaterials

The gastrointestinal (GI) tract is one the biggest mucosal surface in the body and one of the primary targets for the delivery of therapeutics, including immunotherapies. GI diseases, including, e.g., inflammatory bowel disease and intestinal infections such as cholera, pose a significant public health burden and are on the rise. Many of these diseases involve inflammatory processes that can be targeted by immune modulatory therapeutics. However, nonspecific targeting of inflammation systemically can lead to significant side effects. This can be avoided by locally targeting therapeutics to the GI tract and its mucosal immune system. In this review, we discuss nanomaterial-based strategies targeting the GI mucosal immune system, including gut-associated lymphoid tissues, tissue resident immune cells, as well as GI lymph nodes, to modulate GI inflammation and disease outcomes, as well as take advantage of some of the primary mechanisms of GI immunity such as oral tolerance.

Polypeptide-based drug delivery systems for programmed release

Recent years have seen increasing interests in the use of ring-opening polymerization of α-amino acid N-carboxyanhydrides (NCAs) to prepare synthetic polypeptides, a class of biocompatible and versatile materials, for various biomedical applications. Because of their rich side-chain functionalities, diverse hydrophilicity/hydrophobicity profiles, and the capability of forming stable secondary structures, polypeptides can assemble into a variety of well-organized nano-structures that have unique advantages in drug delivery and controlled release. Herein, we review the design and use of polypeptide-based drug delivery system derived from NCA chemistry, and discuss the future perspectives of this exciting and important biomaterial area that may potentially change the landscape of next-generation therapeutics and diagnosis. Given the high significance of precise control over release for polypeptide-based systems, we specifically focus on the versatile designs of drug delivery systems capable of programmed release, through the changes in the chemical and physical properties controlled by the built-in molecular structures of polypeptides.

α-Amino acid N-carboxyanhydride (NCA)-derived synthetic polypeptides for nucleic acids delivery

In recent years, gene therapy has come into the spotlight for the prevention and treatment of a wide range of diseases. Polypeptides have been widely used in mediating nucleic acid delivery, due to their versatilities in chemical structures, desired biodegradability, and low cytotoxicity. Chemistry plays an essential role in the development of innovative polypeptides to address the challenges of producing efficient and safe gene vectors. In this Review, we mainly focused on the latest chemical advances in the design and preparation of polypeptide-based nucleic acid delivery vehicles. We first discussed the synthetic approach of polypeptides via ring-opening polymerization (ROP) of N-carboxyanhydrides (NCAs), and introduced the various types of polypeptide-based gene delivery systems. The extracellular and intracellular barriers against nucleic acid delivery were then outlined, followed by detailed review on the recent advances in polypeptide-based delivery systems that can overcome these barriers to enable in vitro and in vivo gene transfection. Finally, we concluded this review with perspectives in this field.

Biological applications of water-soluble polypeptides with ordered secondary structures

Water-soluble polypeptides are a class of synthetic polymers with peptide bond frameworks imitating natural proteins and have broad prospects in biological applications. The regulation and dynamic transition of the secondary structures of water-soluble polypeptides have a great impact on their physio-chemical properties and biological functions. In this review article, we briefly introduce the current strategies to synthesize polypeptides and modulate their secondary structures. We then discuss the factors affecting the conformational stability/transition of polypeptides and the potential impact of side-chain functionalization on the ordered secondary structures, such as α-helix and β-sheet. We then summarize the biological applications of water-soluble polypeptides such as cell penetration, gene delivery, and antimicrobial treatment, highlighting the important roles of ordered secondary structures therein.

Atomic Engineering of Clusterzyme for Relieving Acute Neuroinflammation through Lattice Expansion

Natural enzymes are efficient and versatile biocatalysts but suffer in their environmental tolerance and catalytic stability. As artificial enzymes, nanozymes can improve the catalytic stability, but it is still a challenge to achieve high catalytic activity. Here, we employed atomic engineering to build the artificial enzyme named Au₂₄Ag₁ clusterzyme that hosts an ultrahigh catalytic activity as well as strong physiological stability via atom manipulation. The designed Au₂₄Ag₁ clusterzyme activates the Ag-S active site via lattice expansion in the oligomer atom layer, showing an antioxidant property 72 times higher than that of natural antioxidant Trolox. Enzyme-mimicked studies find that Au₂₄Ag₁ clusterzyme exhibits high catalase-like (CAT-like) and glutathione peroxidase-like (GPx-like) activity with a maximum reaction rate of 68.9 and 17.8 μM/min, respectively. Meanwhile, the unique catalytic landscape exhibits distinctive reactions against inflammation by inhibiting the cytokines at an early stage in the brain. Atomic engineering of clusterzymes provides a powerful and attractive platform with satisfactory atomic dispersion for tailoring biocatalysts freely at the atomic level.

Supramolecular Assembled Programmable Nanomedicine As In Situ Cancer Vaccine for Cancer Immunotherapy

Using nanotechnology for improving the immunotherapy efficiency represents a major research interest in recent years. However, there are paradoxes and obstacles in using a single nanoparticle to fulfill all the requirements in the complicated immune activation processes. Herein, a supramolecular assembled programmable immune activation nanomedicine (PIAN) for sequentially finishing multiple steps after intravenous injection and eliciting robust antitumor immunity in situ is reported. The programmable nanomedicine is constructed by supramolecular assembly via host-guest interactions between poly-[(N-2-hydroxyethyl)-aspartamide]-Pt(IV)/β-cyclodextrin (PPCD), CpG/polyamidoamine-thioketal-adamantane (CpG/PAMAM-TK-Ad), and methoxy poly(ethylene glycol)-thioketal-adamantane (mPEG-TK-Ad). After intravenous injection and accumulation at the tumor site, the high level of reactive oxygen species in the tumor microenvironment promotes PIAN dissociation and the release of PPCD (mediating tumor cell killing and antigen release) and CpG/PAMAM (mediating antigen capturing and transferring to the tumor-draining lymph nodes). This results in antigen-presenting cell activation, antigen presentation, and robust antitumor immune responses. In combination with anti-PD-L1 antibody, the PIAN cures 40% of mice in a colorectal cancer model. This PIAN provides a new framework for designing programmable nanomedicine as in situ cancer vaccine for cancer immunotherapy.

Synthetic multi-layer nanoparticles for CRISPR-Cas9 genome editing

The clustered regularly interspaced short palindromic repeat (CRISPR) has great potential to revolutionize biomedical research and disease therapy. The specific and efficient genome editing strongly depends on high efficiency of delivery of the CRISPR payloads. However, optimization of CRISPR delivery vehicles still remains a major obstacle. Recently, various non-viral vectors have been utilized to deliver CRISPR tools. Many of these vectors have multi-layer structures assembled. In this review, we will introduce the development of CRISPR-Cas9 systems and their general therapeutic applications by summarizing current CRISPR-Cas9 based clinical trials. We will highlight the multi-layer nanoparticles (NPs) that have been developed to deliver CRISPR cargos in vitro and in vivo for various purposes, as well the potential building blocks of multi-layer NPs. We will also discuss the challenges in making the CRISPR tools into viable pharmaceutical products and provide potential solutions on efficiency and biosafety issues.

Oral Delivery of Biologics for Precision Medicine

The emerging field of precision medicine is rapidly growing, fostered by the advances in genome mapping and molecular diagnosis. In general, the translation of these advances into precision treatments relies on the use of biological macromolecules, whose structure offers a high specificity and potency. Unfortunately, due to their complex structure and limited ability to overcome biological barriers, these macromolecules need to be administered via injection. The scientific community has devoted significant effort to making the oral administration of macromolecules plausible thanks to the implementation of drug delivery technologies. Here, an overview of the current situation and future prospects in the field of oral delivery of biologics is provided. Technologies in clinical trials, as well as recent and disruptive delivery systems proposed in the literature for local and systemic delivery of biologics including peptides, antibodies, and nucleic acids, are described. Strategies for the specific targeting of gastrointestinal regions-stomach, small bowel, and colon-cell populations, and internalization pathways, are analyzed. Finally, challenges associated with the clinical translation, future prospects, and identified opportunities for advancement in this field are also discussed.

Manipulating the helix–coil transition profile of synthetic polypeptides by leveraging side-chain molecular interactions

Based on the pH-sensitive, conformationally tunable triazole polypeptides, we reported the manipulation of helix–coil transition profile determined by the leveraging interactions of the triazole and other side-chain helix-influencing ligands.

TNFα gene silencing mediated by orally targeted nanoparticles combined with interleukin-22 for synergistic combination therapy of ulcerative colitis

Pro-resolving factors that are critical for colonic epithelial restitution were down-regulated during the treatment with inhibitor of pro-inflammatory cytokines (e.g., anti-TNFα antibody) in ulcerative colitis (UC) therapy. We hypothesized that increased amounts of factors such as interleukin-22 (IL-22) during the therapeutic inhibition of TNFα could facilitate the resolution of intestinal inflammation. As combination therapy is an emerging strategy for UC treatment, we attempt to treat established UC based on the combination of TNFα siRNA (siTNF) and IL-22. Initially, we loaded siTNF into galactosylated polymeric nanoparticles (NPs). The resultant Gal-siTNF-NPs had a desirable average diameter (~261 nm), a narrow size distribution and a slightly negative surface charge (~-6 mV). These NPs successfully mediated the targeted delivery of siTNF to macrophages and efficiently inhibited the expression of TNFα. Meanwhile, IL-22 could obviously accelerate mucosal healing. More importantly, oral administration of Gal-siTNF-NPs plus IL-22 embedded in a hydrogel (chitosan/alginate) showed much stronger capacities to down-regulate the expression of pro-inflammatory factors and promote mucosal healing. This formulation also yielded a much better therapeutic efficacy against UC in a mouse model compared to hydrogel loaded with Gal-siTNF-NPs or IL-22 alone. Our results strongly demonstrate that Gal-siTNF-NP/IL-22-embedded hydrogel can target to inflamed colon, and co-deliver siTNF and IL-22 to boost the effects of either monotherapy, which may become a promising oral drug formulation and enable targeted combination therapy of UC.

Systemic siRNA delivery to tumors by cell-penetrating α-helical polypeptide-based metastable nanoparticles

Systemic, non-viral siRNA delivery for cancer treatment is mainly achieved via condensation by cationic materials (e.g., lipids and cationic polymers), which nevertheless, suffers from poor serum stability, non-specific tissue interaction, and unsatisfactory membrane activity against efficient in vivo gene knockdown. Here, we report the design of a metastable, cancer-targeting siRNA delivery system based on two functional polymers, PVBLG-8, a cationic, helical cell-penetrating polypeptide, and poly(l-glutamic acid) (PLG), an anionic random-coiled polypeptide. PVBLG-8 with rigid, linear structure showed weak siRNA condensation capability, and PLG with flexible chains was incorporated as a stabilizer which provided sufficient molecular entanglement with PVBLG-8 to encapsulate the siRNA within the polymeric network. The obtained PVBLG-8/siRNA/PLG nanoparticles (PSP NPs) with positive charges were sequentially coated with additional amount of PLG, which reversed the surface charge from positive to negative to yield the metastable PVBLG-8/siRNA/PLG@PLG (PSPP) NPs. The PSPP NPs featured desired serum stability during circulation to enhance tumor accumulation via the enhanced permeability and retention (EPR) effect. Upon acidification in the tumor extracellular microenvironment and intracellular endosomes, the partial protonation of PLG on PSPP NPs surface would lead to dissociation of PLG coating from NPs, exposure of the highly membrane-active PVBLG-8, and surface charge reversal from negative to positive, which subsequently promoted tumor penetration, selective cancer cell internalization, and efficient endolysosomal escape. When siRNA against epidermal growth factor receptor (EGFR) was encapsulated, the PSPP NPs showed excellent tumor penetration capability, tumor cell uptake level, EGFR silencing efficiency, and tumor growth inhibition efficacy in U-87 MG glioblastoma tumor spheroids in vitro and in xenograft tumor-bearing mice in vivo, outperforming the PSP NPs and several commercial reagents such as Lipofectamine 2000 and poly(l-lysine) (PLL). This study therefore demonstrates a facile and unique design approach of metastable and charge reversal NPs, which overcomes multiple biological barriers against systemic siRNA delivery toward anti-cancer treatment.

Polyphenol-Poloxamer Self-Assembled Supramolecular Nanoparticles for Tumor NIRF/PET Imaging

Self-assembled supramolecular nanoparticles have remarkable benefits in bioimaging and drug delivery. Here it is first reported that polyphenol and poloxamer self-assemble supramolecular nanoparticles (PPNPs). PPNPs are fabricated by multivalent hydrogen bonding between tannic acid and Pluronic F-127 together with hydrophobic interactions of poly(propylene oxide) chains, to be applied in tumor near-infrared fluorescence (NIRF) imaging and positron emission tomography (PET) imaging. With near-infrared fluorescent dyes such as IR780 encapsulated via hydrophobic interactions, PPNPs are used in NIRF imaging. PPNPs with excess phenolic hydroxyl groups chelating positron emitting radionuclide ⁸⁹ Zr function as a PET contrast agent. The in vivo results show surprisingly higher fluorescence intensity in tumors than in other tissues. In addition, PPNPs exhibit good biocompatibility in various cell lines and do not induce hemolysis in vitro. In this study, it is demonstrated that biodegradable and biocompatible PPNPs are an excellent bimodal contrast agent for in vivo tumor imaging.

Nanocapsule-mediated cytosolic siRNA delivery for anti-inflammatory treatment

The use of nanoparticle-stabilized nanocapsules for cytosolic siRNA delivery for immunomodulation in vitro and in vivo is reported. These NPSCs deliver siRNA directly to the cytosol of macrophages in vitro with concomitant knockdown of gene expression. In vivo studies showed directed delivery of NPSCs to the spleen, enabling gene silencing of macrophages, with preliminary studies showing 70% gene knockdown at a siRNA dose of 0.28 mg/kg. Significantly, the delivery of siRNA targeting tumor necrosis factor-α efficiently silenced TNF-α expression in LPS-challenged mice, demonstrating efficacy in modulating immune response in an organ-selective manner. This research highlights the potential of the NPSC platform for targeted immunotherapy and further manipulation of the immune system.

Knockdown of TNF‑α alleviates acute lung injury in rats with intestinal ischemia and reperfusion injury by upregulating IL‑10 expression

Intestinal ischemia and reperfusion (II/R) injury often triggers severe injury in remote organs, with the lungs being considered the main target. Excessive elevation of proinflammatory cytokines is a major contributor in the occurrence and development of II/R-induced acute lung injury (ALI). Therefore, the present study aimed to investigate whether blocking tumor necrosis factor-α (TNF-α) expression could protect the lungs from injury following II/R, and to explore the possible underlying mechanism involving interleukin-10 (IL-10). Briefly, II/R was induced in rats by 40 min occlusion of the superior mesenteric artery and celiac artery, followed by 8, 16 or 24 h of reperfusion. Subsequently, lentiviral vectors containing TNF-α short hairpin (sh)RNA were injected into the right lung tissues, in order to induce TNF-α knockdown. The severity of ALI was determined according to lung injury scores and lung edema (lung wet/dry weight ratio). The expression levels of TNF-α were analyzed by quantitative polymerase chain reaction (qPCR), western blotting and immunofluorescence (IF) staining. IL-10 expression, in response to TNF-α knockdown, was detected in lung tissues by qPCR and IF. The results detected marked inflammatory responses, and increased levels of lung wet/dry weight ratio and TNF-α expression, in the lungs of II/R rats. Conversely, treatment with TNF-α shRNA significantly alleviated the severity of ALI and upregulated the expression levels of IL-10 in lung tissues. These findings suggested that TNF-α RNA interference may exert a protective effect on II/R-induced ALI via the upregulation of IL-10. Therefore, TNF-α knockdown may be considered a potential strategy for the prevention or treatment of ALI induced by II/R in future clinical trials.

Therapeutic approaches for the delivery of TNF-α siRNA

Immune-mediated diseases are emerging as a major healthcare concern in the present era. TNF-α, a proinflammatory cytokine, plays a major role in the manifestation of these diseases by mediating different pathways and inducing the expression of other cytokines. In last decades, monoclonal antibodies and extracellular portion of human TNF-α receptors are explored in this area; however, the risk of immunological response and undesired effects urge a need to develop more effective therapies to control TNF-α levels. siRNA therapeutic strategies are emerging for the treatment of myriad of diseases, but the delivery challenges associated with siRNA require the development of suitable delivery vectors. For delivery of TNF-α siRNA, both viral and nonviral vectors are explored. This review attempts to describe different delivery approaches for TNF-α siRNA with special focus on nonviral delivery vectors.

Nonviral gene editing via CRISPR/Cas9 delivery by membrane-disruptive and endosomolytic helical polypeptide

Effective and safe delivery of the CRISPR/Cas9 gene-editing elements remains a challenge. Here we report the development of PEGylated nanoparticles (named P-HNPs) based on the cationic α-helical polypeptide poly(γ-4-((2-(piperidin-1-yl)ethyl)aminomethyl)benzyl-l-glutamate) for the delivery of Cas9 expression plasmid and sgRNA to various cell types and gene-editing scenarios. The cell-penetrating α-helical polypeptide enhanced cellular uptake and promoted escape of pCas9 and/or sgRNA from the endosome and transport into the nucleus. The colloidally stable P-HNPs achieved a Cas9 transfection efficiency up to 60% and sgRNA uptake efficiency of 67.4%, representing an improvement over existing polycation-based gene delivery systems. After performing single or multiplex gene editing with an efficiency up to 47.3% in vitro, we demonstrated that P-HNPs delivering Cas9 plasmid/sgRNA targeting the polo-like kinase 1 (Plk1) gene achieved 35% gene deletion in HeLa tumor tissue to reduce the Plk1 protein level by 66.7%, thereby suppressing the tumor growth by >71% and prolonging the animal survival rate to 60% within 60 days. Capable of delivering Cas9 plasmids to various cell types to achieve multiplex gene knock-out, gene knock-in, and gene activation in vitro and in vivo, the P-HNP system offers a versatile gene-editing platform for biological research and therapeutic applications.

Oral delivery of siRNA lipid nanoparticles: Fate in the GI tract

Oral delivery, a patient-friendly means of drug delivery, is preferred for local administration of intestinal therapeutics. Lipidoid nanoparticles, which have been previously shown to deliver siRNA to intestinal epithelial cells, have potential to treat intestinal disease. It is unknown, however, whether the oral delivery of these particles is possible. To better understand the fate of lipid nanoparticles in the gastrointestinal (GI) tract, we studied delivery under deconstructed stomach and intestinal conditions in vitro. Lipid nanoparticles remained potent and stable following exposure to solutions with pH values as low as 1.2. Efficacy decreased following exposure to “fed”, but not “fasting” concentrations of pepsin and bile salts. The presence of mucin on Caco-2 cells also reduced potency, although this effect was mitigated slightly by increasing the percentage of PEG in the lipid nanoparticle. Mouse biodistribution studies indicated that siRNA-loaded nanoparticles were retained in the GI tract for at least 8 hours. Although gene silencing was not initially observed following oral LNP delivery, confocal microscopy confirmed that nanoparticles entered the epithelial cells of the mouse small intestine and colon. Together, these data suggest that orally-delivered LNPs should be protected in the stomach and upper intestine to promote siRNA delivery to intestinal epithelial cells.

Secondary structures in synthetic polypeptides from N-carboxyanhydrides: design, modulation, association, and material applications

This article highlights the conformation-specific properties and functions of synthetic polypeptides derived from N-carboxyanhydrides.

Macrophage-targeting and reactive oxygen species (ROS)-responsive nanopolyplexes mediate anti-inflammatory siRNA delivery against acute liver failure (ALF)

Macrophage-targeting and ROS-degradable nanopolyplexes were developed to realize efficient TNF-α siRNA delivery toward the treatment of acute liver failure.

Virus-Mimicking Chimaeric Polymersomes Boost Targeted Cancer siRNA Therapy In Vivo

Small interfering RNA (siRNA) offers a highly selective and effective pharmaceutical for various life-threatening diseases, including cancers. The clinical translation of siRNA is, however, challenged by its short plasma life, poor cell uptake, and cumbersome intracellular trafficking. Here, cNGQGEQc peptide-functionalized reversibly crosslinked chimaeric polymersomes (cNGQ/RCCPs) is shown to mediate high-efficiency targeted delivery of Polo-like kinase1 specific siRNA (siPLK1) to orthotopic human lung cancer in nude mice. Strikingly, siRNA is completely and tightly loaded into the aqueous lumen of the polymersomes at an unprecedentedly low N/P ratio of 0.45. cNGQ/RCCPs loaded with firefly luciferase specific siRNA (siGL3) or siPLK1 are efficiently taken up by α₃ β₁ -integrin-overexpressing A549 lung cancer cells and quickly release the payloads to the cytoplasm, inducing highly potent and sequence-specific gene silencing in vitro. The in vivo studies using nude mice bearing orthotopic A549 human lung tumors reveal that siPLK1-loaded cNGQ/RCCPs boost long circulation, superb tumor accumulation and selectivity, effective suppression of tumor growth, and significantly improved survival time. These virus-mimicking chimaeric polymersomes provide a robust and potent platform for targeted cancer siRNA therapy.

Synthetic polypeptides: from polymer design to supramolecular assembly and biomedical application

Synthetic polypeptides from the ring-opening polymerization of N-carboxyanhydrides (NCAs) are one of the most important biomaterials. The unique features of these synthetic polypeptides, including their chemical diversity of side chains and their ability to form secondary structures, enable their broad applications in the field of gene delivery, drug delivery, bio-imaging, tissue engineering, and antimicrobials. In this review article, we summarize the recent advances in the design of polypeptide-based supramolecular structures, including complexes with nucleic acids, micelles, vesicles, hybrid nanoparticles, and hydrogels. We also highlight the progress in the chemical design of functional polypeptides, which plays a crucial role to manipulate their assembly behaviours and optimize their biomedical performances. Finally, we conclude the review by discussing the future opportunities in this field, including further studies on the secondary structures and cost-effective synthesis of polypeptide materials.

Engineering the Aromaticity of Cationic Helical Polypeptides toward "Self-Activated" DNA/siRNA Delivery

The development of potent yet nontoxic membrane-penetrating materials is in high demand for effective intracellular gene delivery. We have recently developed α-helical polypeptides which afford potent membrane activities to facilitate intracellular DNA delivery via both endocytosis and the nonendocytic "pore formation" mechanism. Endocytosis will cause endosomal entrapment of the DNA cargo, while excessive "pore formation" would cause appreciable cytotoxicity. Additionally, helical polypeptides with stiff, rodlike structure suffer from low siRNA binding affinity. To address such critical issues, we herein incorporated various aromatic domains (benzyl, naphthyl, biphenyl, anthryl, and pyrenyl) into the side-chain terminals of guanidine-rich, helical polypeptides, wherein the flat-rigid shape, π-electronic structures of aromatic motifs "self-activated" the membrane-penetrating capabilities of polypeptides to promote intracellular gene delivery. Benzyl (Bn)- and naphthyl (Naph)-modified polypeptides demonstrated the highest DNA uptake level that outperformed the unmodified polypeptide, P2, by ∼4 fold. More importantly, compared with P2, Bn- and Naph-modified polypeptides allowed more DNA cargos to be internalized via the nonendocytic pathway, which significantly bypassed the endosomal entrapment and accordingly enhanced the transfection efficiency by up to 42 fold, outperforming PEI 25k as the commercial reagent by 3-4 orders of magnitude. The aromatic modification also improved the siRNA condensation capability of polypeptides, achieving notably enhanced gene-silencing efficiency against tumor necrosis factor-α to treat acute hepatic inflammation. Furthermore, we revealed that aromaticity-augmented membrane activity was accompanied by comparable or even significantly reduced "pore formation" capability, thus leading to diminished cytotoxicity at high concentrations. This study therefore provides a promising approach to manipulate the membrane activities and penetration mechanisms of polycations, which overcomes the multiple critical barriers preventing effective and safe gene delivery.

pH-controllable cell-penetrating polypeptide that exhibits cancer targeting

Helical peptides were naturally-occurring ordered conformations that mediated various biological functions essential for biotechnology. However, it was difficult for natural helical polypeptides to be applied in biomedical fields due to low bioavailability. To avoid these problems, synthetic alpha-helical polypeptides have recently been introduced by further modifying pendants in the side chain. In spite of an attractive biomimetic helical motif, these systems could not be tailored for targeted delivery mainly due to nonspecific binding events. To address these issues, we created a conformation-transformable polypeptide capable of eliciting a pH-activated cell-penetrating property solely at the cancer region. The developed novel polypeptide showed that the bare helical conformation had a function at physiological conditions while the pH-induced helical motif provided an active cell-penetrating characteristic at a tumor extracellular matrix pH. The unusual conformation-transformable system can elicit bioactive properties exclusively at mild acidic pH.

STATEMENT OF SIGNIFICANCE

We developed pH-controllable cell-penetrating polypeptides (PCCPs) undergoing pH-induced conformational transitions. Unlike natural cell-penetrating peptides, PCCPs was capable of penetrating the plasma membranes dominantly at tumor pH, driven by pH-controlled helicity. The conformation of PCCPs at neutral pH showed low helical propensity because of dominant electrostatic attractions within the side chains. However, the helicity of PCCPs was considerably augmented by the balance of electrostatic interactions, thereby inducing selective cellular penetration. Three polypeptides undergoing different conformational transitions were prepared to verify the selective cellular uptake influenced by their structures. The PCCP undergoing low-to-high helical conformation provided the tumor specificity and enhanced uptake efficiency. pH-induced conformation-transformable polypeptide might provide a novel platform for stimuli-triggered targeting systems.

Oral nucleic acid therapy using multicompartmental delivery systems

Nucleic acid-based therapeutics has the potential for treating numerous diseases by correcting abnormal expression of specific genes. Lack of safe and efficacious delivery strategies poses a major obstacle limiting clinical advancement of nucleic acid therapeutics. Oral route of drug administration has greater delivery challenges, because the administered genes or oligonucleotides have to bypass degrading environment of the gastrointestinal (GI) tract in addition to overcoming other cellular barriers preventing nucleic acid delivery. For efficient oral nucleic acid delivery, vector should be such that it can protect encapsulated material during transit through the GI tract, facilitate efficient uptake and intracellular trafficking at desired target sites, along with being safe and well tolerated. In this review, we have discussed multicompartmental systems for overcoming extracellular and intracellular barriers to oral delivery of nucleic acids. A nanoparticles-in-microsphere oral system-based multicompartmental system was developed and tested for in vivo gene and small interfering RNA delivery for treating colitis in mice. This system has shown efficient transgene expression or gene silencing when delivered orally along with favorable downstream anti-inflammatory effects, when tested in a mouse model of intestinal bowel disease. WIREs Nanomed Nanobiotechnol 2018, 10:e1478. doi: 10.1002/wnan.1478 This article is categorized under: Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Evaluation of Maltose-Based Cationic Liposomes with Different Hydrophobic Tails for Plasmid DNA Delivery

In this paper, three cationic glycolipids with different hydrophobic chains Malt-DiC12MA (IX a), Malt-DiC14MA (IX b) and Malt-DiC16MA (IX c) were constructed by using maltose as starting material via peracetylation, selective 1-O-deacetylation, trichloroacetimidation, glycosylation, azidation, deacetylation, Staudinger reaction, tertiary amination and quaternization. Target compounds and some intermediates were characterized by ¹H-NMR, ¹³C-NMR, ¹H-¹H COSY and ¹H-¹³C HSQC. The results of gel electrophoresis assay, atomic force microscopy images (AFM) and dynamic light scattering (DLS) demonstrate that all the liposomes could efficiently bind and compact DNA (N/P ratio less than 2) into nanoparticles with proper size (88 nm–146 nm, PDI < 0.4) and zeta potential (+15 mV–+26 mV). The transfection efficiency and cellular uptake of glycolipids in HEK293 cell were evaluated through the enhanced green fluorescent protein (EGFP) expression and Cy3-labeled pEGFP-C1 (Enhanced Green Fluorescent Protein plasmid) images, respectively. Importantly, it indicated that Malt-DiC14MA exhibited high gene transfer efficiency and better uptake capability at N/P ratios of 8:1. Additionally, the result of cell viability showed glycolipids exhibited low biotoxicity and good biocompatibility by thiazolyl blue tetrazolium bromide (MTT) assay.

SiRNA Crosslinked Nanoparticles for the Treatment of Inflammation-induced Liver Injury

RNA interference mediated by small interfering RNA (siRNA) provides a powerful tool for gene regulation, and has a broad potential as a promising therapeutic strategy. However, therapeutics based on siRNA have had limited clinical success due to their undesirable pharmacokinetic properties. This study presents pH-sensitive nanoparticles-based siRNA delivery systems (PNSDS), which are positive-charge-free nanocarriers, composed of siRNA chemically crosslinked with multi-armed poly(ethylene glycol) carriers via acid-labile acetal linkers. The unique siRNA crosslinked structure of PNSDS allows it to have minimal cytotoxicity, high siRNA loading efficiency, and a stimulus-responsive property that enables the selective intracellular release of siRNA in response to pH conditions. This study demonstrates that PNSDS can deliver tumor necrosis factor alpha (TNF-α) siRNA into macrophages and induce the efficient down regulation of the targeted gene in complete cell culture media. Moreover, PNSDS with mannose targeting moieties can selectively accumulate in mice liver, induce specific inhibition of macrophage TNF-α expression in vivo, and consequently protect mice from inflammation-induced liver damages. Therefore, this novel siRNA delivering platform would greatly improve the therapeutic potential of RNAi based therapies.

Peptides, polypeptides and peptide–polymer hybrids as nucleic acid carriers

Peptide, polypeptide and polymer–peptide hybrid based nucleic acid therapeutics (NAT).

Serum-resistant, reactive oxygen species (ROS)-potentiated gene delivery in cancer cells mediated by fluorinated, diselenide-crosslinked polyplexes

Fluorinated, diselenide-crosslinked polyplexes were developed to enable ROS-responsive and serum-resistant gene delivery in cancer cells.

Efficient Targeting of Adipose Tissue Macrophages in Obesity with Polysaccharide Nanocarriers

Obesity leads to an increased risk for type 2 diabetes, heart disease, stroke, and cancer. The causal link between obesity and these pathologies has recently been identified as chronic low-grade systemic inflammation initiated by pro-inflammatory macrophages in visceral adipose tissue. Current medications based on small-molecule drugs yield significant off-target side effects with long-term use, and therefore there is a major need for targeted therapies. Here we report that nanoscale polysaccharides based on biocompatible glucose polymers can efficiently target adipose macrophages in obese mice. We synthesized a series of dextran conjugates with tunable size linked to contrast agents for positron emission tomography, fluorophores for optical microscopy, and anti-inflammatory drugs for therapeutic modulation of macrophage phenotype. We observed that larger conjugates efficiently distribute to visceral adipose tissue and selectively associate with macrophages after regional peritoneal administration. Up to 63% of the injected dose remained in visceral adipose tissue 24 h after administration, resulting in >2-fold higher local concentration compared to liver, the dominant site of uptake for most nanomedicines. Furthermore, a single-dose treatment of anti-inflammatory conjugates significantly reduced pro-inflammatory markers in adipose tissue of obese mice. Importantly, all components of these therapeutic agents are approved for clinical use. This work provides a promising nanomaterials-based delivery strategy to inhibit critical factors leading to obesity comorbidities and demonstrates a unique transport mechanism for drug delivery to visceral tissues. This approach may be further applied for high-efficiency targeting of other inflammatory diseases of visceral organs.

Multifunctional Environmental Smart Fertilizer Based on l-Aspartic Acid for Sustained Nutrient Release

Fertilizer is one of the most important elements of modern agriculture. However, conventional fertilizer, when applied to crops, is vulnerable to losses through volatilization, leaching, nitrification, or other means. Such a loss limits crop yields and pollutes the environment. In an effort to enhance nutrient use efficiency and reduce environmental pollution, an environmental smart fertilizer was reported in the current study. Poly(aspartic acid) and a degradable macro-cross-linker based on l-aspartic acid were synthesized and introduced into the fertilizer as a superabsorbent to improve the fertilizer degradability and soil moisture-retention capacity. Sustained release behavior of the fertilizer was achieved in soil. Cumulative release of nitrogen and phosphorus was 79.8% and 64.4% after 30 days, respectively. The water-holding and water-retention capacities of soil with the superabsorbent are obviously higher than those of the control soil without superabsorbent. For the sample of 200 g of soil with 1.5 g of superabsorbent, the water-holding capacity is 81.8%, and the water-retention capacity remains 22.6% after 23 days. All of the current results in this study indicated that the as-prepared fertilizer has a promising application in sustainable modern agriculture.

Bilirubin Nanoparticles as a Nanomedicine for Anti-inflammation Therapy

Despite the high potency of bilirubin as an endogenous anti-inflammatory compound, its clinical translation has been hampered because of its insolubility in water. Bilirubin-based nanoparticles that may overcome this critical issue are presented. A polyethylene glycol compound (PEG) was covalently attached to bilirubin, yielding PEGylated bilirubin (PEG-BR). The PEG-BR self-assembled into nanoscale particles with a size of approximately 110 nm, termed bilirubin nanoparticles (BRNPs). BRNPs are highly efficient hydrogen peroxide scavengers, thereby protecting cells from H2 O2 -induced cytotoxicity. In a murine model of ulcerative colitis, intravenous injection of BRNPs showed preferential accumulation of nanoparticles at the sites of inflammation and significantly inhibited the progression of acute inflammation in the colon. Taken together, BRNPs show potential for use as a therapeutic nanomedicine in various inflammatory diseases.

CD44 Mediated Nonviral Gene Delivery into Human Embryonic Stem Cells via Hyaluronic-Acid-Coated Nanoparticles

Gene delivery is an important tool to study and manipulate human pluripotent stem cells for regenerative medicine purposes. Yet current methods of transient gene delivery to stem cells are still inefficient. Through the combination of biologically based concepts and material design, we aim to develop new methods to enhance the efficiency of gene delivery to stem cells. Specifically, we use poly(γ-4-(((2-(piperidin-1-yl)ethyl)amino)methyl)benzyl-l-glutamate) (PVBLG-8), a membrane-active helical, cationic polypeptide, to condense plasmid DNA to form stable nanocomplexes, which are further coated with hyaluronic acid (HA). HA not only shields the positive charges of PVBLG-8 to reduce toxicity, but also acts as a targeting moiety for cell surface receptor CD44, which binds HA and facilitates the internalization of the nanocomplexes. Upon entering cells, HA is degraded by hyaluronidase in endosomes and PVBLG-8 is exposed, facilitating the endosomal escape of DNA/polypeptide complex. Our studies show that the coating of HA significantly increases gene transfection efficiency of DNA/PVBLG-8 nanocomplexes from about 28 to 36% with largely reduced toxicity.