In Situ Gelling Liquid Crystalline System as Local siRNA Delivery System

Flavonoid extract from propolis alleviates periodontitis by boosting periodontium regeneration and inflammation resolution via regulating TLR4/MyD88/NF-κB and RANK/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, propolis has been used for treating oral diseases for centuries, widely. Flavonoid extract is the main active ingredient in propolis, which has attracted extensive attention in recent years.

AIM OF THE STUDY

The objective and novelty of the current study aims to identify the mechanism of total flavonoid extract of propolis (TFP) for the treatment of periodontitis, and evaluate the therapeutic effect of TFP-loaded liquid crystal hydrogel (TFP-LLC) in rats with periodontitis.

METHODS

In this study, we used lipopolysaccharide-stimulated periodontal ligament stem cells (PDLSCs) to construct in vitro inflammation model, and investigated the anti-inflammatory effect of TFP by expression levels of inflammatory factors. Osteogenic differentiation was assessed using alkaline phosphatase activity and alizarin red staining. Meanwhile, the expression of toll like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), nuclear factor-kappa B (NF-κB), receptor activator of NF-κB (RANK) etc, were quantitated to investigate the therapeutic mechanism of TFP. Finally, we constructed TFP-LLC using a self-emulsification method and administered it to rats with periodontitis via periodontal pocket injection to evaluate the therapeutic effects. The therapeutic index, microcomputed tomography (Micro-CT), H&E staining, TRAP staining, and Masson staining were used for this evaluation.

RESULTS

TFP reduced the expression of TLR4, MyD88, NF-κB and inflammatory factor in lipopolysaccharide-stimulated PDLSCs. Meanwhile, TFP simultaneously regulating alkaline phosphatase, RANK, runt-associated transcription factor-2 and matrix metalloproteinase production to accelerate osteogenic differentiation and collagen secretion. In addition, TFP-LLC can stably anchor to the periodontal lesion site and sustainably release TFP. After four weeks of treatment with TFP-LLC, we observed a decrease in the levels of NF-κB and interleukin-1β (IL-1β) in the periodontal tissues of rats, as well as a significant reduction in inflammation in HE staining. Similarly, Micro CT results showed that TFP-LLC could significantly inhibit alveolar bone resorption, increase bone mineral density (BMD) and reduce trabecular bone space (Tb.Sp) in rats with periodontitis.

CONCLUSION

Collectively, we have firstly verified the therapeutic effects and mechanisms of TFP in PDLSCs for periodontitis treatment. Our results indicate that TFP perform anti-inflammatory and tissue repair activities through TLR4/MyD88/NF-κB and RANK/NF-κB pathways in PDLSCs. Meanwhile, for the first time, we employed LLC delivery system to load TFP for periodontitis treatment. The results showed that TFP-LLC could be effectively retained in the periodontal pocket and exerted a crucial role in inflammation resolution and periodontal tissue regeneration.

Solid Lipid-Polymer Hybrid Nanoplatform for Topical Delivery of siRNA: In Vitro Biological Activity and Permeation Studies

Small interfering RNA (siRNA) molecules have limited transfection efficiency and stability, necessitating the use of delivery systems to be effective in gene knockdown therapies. In this regard, lipid-polymeric nanocarriers have emerged as a promising class of nanoparticles for siRNA delivery, particularly for topical applications. We proposed the use of solid lipid-polymer hybrid nanoparticles (SLPHNs) as topical delivery systems for siRNA. This approach was evaluated by assessing the ability of SLPHNs-siRNA complexes to internalize siRNA molecules and both to penetrate skin layers in vitro and induce gene knocking down in a skin cell line. The SLPHNs were formed by a specific composition of solid lipids, a surfactant polymer as a dispersive agent, and a cationic polymer as a complexing agent for siRNA. The optimized nanocarriers exhibited a spherical shape with a smooth surface. The average diameter of the nanoparticles was found to be 200 nm, and the zeta potential was measured to be +20 mV. Furthermore, these nanocarriers demonstrated excellent stability when stored at 4 °C over a period of 90 days. In vitro and in vivo permeation studies showed that SLPHNs increased the cutaneous penetration of fluorescent-labeled siRNA, which reached deeper skin layers. Efficacy studies were conducted on keratinocytes and fibroblasts, showing that SLPHNs maintained cell viability and high cellular uptake. Furthermore, SLPHNs complexed with siRNA against Firefly luciferase (siLuc) reduced luciferase expression, proving the efficacy of this nanocarrier in providing adequate intracellular release of siRNA for silencing specific genes. Based on these results, the developed carriers are promising siRNA delivery systems for skin disease therapy.

Intranasal in situ gelling liquid crystal for delivery of resveratrol ameliorates memory and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is an illness that affects people aged 65 or older and affects around 6.5 million in the United States. Resveratrol is a chemical obtained from natural products and it exhibits biological activity based on inhibiting the formation, depolymerization of the amyloid, and decreasing neuroinflammation. Due to the insolubility of this compound; its incorporation in surfactant-based systems was proposed to design an intranasal formulation. A range of systems has been produced by mixing oleic acid, CETETH-20 and water. Polarised light microscopy (PLM), small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm the initial liquid formulation (F) presented as microemulsion (ME). After dilution, the gelled systems were characterized as hexagonal mesophase and they showed feasibility proprieties. Pharmacological assays performed after intranasal administration showed the ability to improve learning and memory in animals, as well as remission of neuroinflammation via inhibition of interleukin.

Lipidic lyotropic liquid crystals: Insights on biomedical applications

Liquid crystals (LCs) possess unique physicochemical properties, translatable into a wide range of applications. To date, lipidic lyotropic LCs (LLCs) have been extensively explored in drug delivery and imaging owing to the capability to encapsulate and release payloads with different characteristics. The current landscape of lipidic LLCs in biomedical applications is provided in this review. Initially, the main properties, types, methods of fabrication and applications of LCs are showcased. Then, a comprehensive discussion of the main biomedical applications of lipidic LLCs accordingly to the application (drug and biomacromolecule delivery, tissue engineering and molecular imaging) and route of administration is examined. Further discussion of the main limitations and perspectives of lipidic LLCs in biomedical applications are also provided. STATEMENT OF SIGNIFICANCE: Liquid crystals (LCs) are those systems between a solid and liquid state that possess unique morphological and physicochemical properties, translatable into a wide range of biomedical applications. A short description of the properties of LCs, their types and manufacturing procedures is given to serve as a background to the topic. Then, the latest and most innovative research in the field of biomedicine is examined, specifically the areas of drug and biomacromolecule delivery, tissue engineering and molecular imaging. Finally, prospects of LCs in biomedicine are discussed to show future trends and perspectives that might be utilized. This article is an ampliation, improvement and actualization of our previous short forum article "Bringing lipidic lyotropic liquid crystal technology into biomedicine" published in TIPS.

Lyotropic liquid crystals for parenteral drug delivery

The necessity for long-term treatments of chronic diseases has encouraged the development of novel long-acting parenteral formulations intending to improve drug pharmacokinetics and therapeutic efficacy. Lately, one of the novel approaches has been developed based on lipid-based liquid crystals. The lyotropic liquid crystal (LLC) systems consist of amphiphilic molecules and are formed in presence of solvents with the most common types being cubic, hexagonal and lamellar mesophases. LC injectables have been recently developed based on polar lipids that spontaneously form liquid crystal nanoparticles in aqueous tissue environments to create the in-situ long-acting sustained-release depot to provide treatment efficacy over extended periods. In this manuscript, we have consolidated and summarized the various type of liquid crystals, recent formulation advancements, analytical evaluation, and therapeutic application of lyotropic liquid crystals in the field of parenteral sustained release drug delivery.

TNFα siRNA delivery by nanoparticles and photochemical internalization for psoriasis topical therapy

Psoriasis is a chronic inflammatory skin disease that presents increased expression of tumor necrosis factor α (TNFα), a proinflammatory cytokine. The discovery of RNA interference (RNAi), mediated by short interfering RNA (siRNA), made it possible for the expression of some genes to be eliminated. However, for its application, it is necessary to use carriers that can protect siRNA and release it in the target cells. Herein, we developed a delivery system for siRNA based on hybrid polymer-lipid nanoparticles (PLNs) and combined this system with photochemical internalization (PCI), photoactivating the photosensitizer TPPS2a, to optimize the endosomal escape of TNFα siRNA in the cytoplasm, aiming to use the system as a topical formulation to treat psoriasis. The PLNs composed of 2.0% of Compritol® 888 ATO (lipid), 1.5% of poloxamer 188 and 0.1% of the cationic polymer poly(allylamine hydrochloride) showed an average nanoparticle size of 142 nm, a zeta potential of +25 mV, and the ability to efficiently coencapsulate TPPS2a and complexed siRNA. In addition, these materials did not present cellular toxicity and showed high cellular uptake. In vitro delivery studies using porcine skin model revealed that the PLNs delivered siRNA and TPPS2a into the skin. The efficacy was verified using an in vivo psoriasis animal (hairless mouse) model induced by imiquimod (IMQ) cream. The results revealed that PLN-TPPS2a-TNFα siRNA combined with PCI resulted in a decrease in the levels of TNFα, showing the efficiency of the treatment to silence this cytokine in psoriatic lesions, which was accompanied by a reduction in the redness and scaling of the mouse skin. The results showed the potential of the developed PLNs in combined silencing gene therapy and PCI for topical treatment of psoriasis.

An overview of PLGA in-situ forming implants based on solvent exchange technique: effect of formulation components and characterization

As a result of the low oral bioavailability of several drugs, there is a renewed interest for parenteral administration to target their absorption directly into the blood bypassing the long gastrointestinal route and hepatic metabolism. In order to address the potential side effects of frequent injections, sustained release systems are the most popular approaches for achieving controlled long-acting drug delivery. Injectable in-situ forming implants (ISFIs) have gained greater popularity in comparison to other sustained systems. Their significant positive aspects are attributed to easier production, acceptable administration route, reduced dosing frequency and patient compliance achievement. ISFI systems, comprising biodegradable polymers such as poly (lactide-co-glycolide) (PLGA) based on solvent exchange mechanisms, are emerged as liquid formulations that develop solid or semisolid depots after injection and deliver drugs over extended periods. The drug release from ISFI systems is generally characterized by an initial burst during the matrix solidification, followed by diffusion processes and finally polymeric degradation and erosion. The choice of suitable solvent with satisfactory viscosity, miscibility and biocompatibility along with considerable PLGA hydrophobicity and molecular weights is fundamental for optimizing the drug release. This overview gives a particular emphasis on evaluations and the wide ranges of requirements needed to achieve reasonable physicochemical characteristics of ISFIs.

In situ monitoring of the formation of lipidic non-lamellar liquid crystalline depot formulations in synovial fluid

Administration of parenteral liquid crystalline phases, forming in-vivo with tunable nanostructural features and sustained release properties, offers an attractive approach for treatment of infections and local drug delivery. It has also a potential use for postoperative pain management after arthroscopic knee surgery. However, the optimal use of this drug delivery principle requires an improved understanding of the involved dynamic structural transitions after administration of low-viscous stimulus-responsive lipid precursors and their fate after direct contact with the biological environment. These precursors (preformulations) are typically based on a single biologically relevant lipid (or a lipid combination) with non-lamellar liquid crystalline phase forming propensity. In relation to liquid crystalline depot design for intra-articular drug delivery, it was our interest in the present study to shed light on such dynamic structural transitions by combining synchrotron SAXS with a remote controlled addition of synovial fluid (or buffer containing 2% (w/v) albumin). This combination allowed for monitoring in real-time the hydration-triggered dynamic structural events on exposure of the lipid precursor (organic stock solution consisting of the binary lipid mixture of monoolein and castor oil) to excess synovial fluid (or excess buffer). The synchrotron SAXS findings indicate a fast generation of inverse bicontinuous cubic phases within few seconds. The effects of (i) the organic solvent N-methyl-2-pyrolidone (NMP), (ii) the lipid composition, and (iii) the albumin content on modulating the structures of the self-assembled lipid aggregates and the implications of the experimental findings in the design of liquid crystalline depots for intra-articular drug delivery are discussed.

Nanotechnology approaches in the current therapy of skin cancer

Skin cancer is a high burden disease with a high impact on global health. Conventional therapies have several drawbacks; thus, the development of effective therapies is required. In this context, nanotechnology approaches are an attractive strategy for cancer therapy because they enable the efficient delivery of drugs and other bioactive molecules to target tissues with low toxic effects. In this review, nanotechnological tools for skin cancer will be summarized and discussed. First, pathology and conventional therapies will be presented, followed by the challenges of skin cancer therapy. Then, the main features of developing efficient nanosystems will be discussed, and next, the most commonly used nanoparticles (NPs) described in the literature for skin cancer therapy will be presented. Subsequently, the use of NPs to deliver chemotherapeutics, immune and vaccine molecules and nucleic acids will be reviewed and discussed as will the combination of physical methods and NPs. Finally, multifunctional delivery systems to codeliver anticancer therapeutic agents containing or not surface functionalization will be summarized.

Improved Nucleic Acid Therapy with Advanced Nanoscale Biotechnology

Due to a series of systemic and intracellular obstacles in nucleic acid (NA) therapy, including fast degradation in blood, renal clearance, poor cellular uptake, and inefficient endosomal escape, NAs may need delivery methods to transport to the cell nucleus or cytosol to be effective. Advanced nanoscale biotechnology-associated strategies, such as controlling the particle size, charge, drug loading, response to environmental signals, or other physical/chemical properties of delivery carriers, have provided great help for the in vivo and in vitro delivery of NA therapeutics. In this review, we introduce the characteristics of different NA modalities and illustrate how advanced nanoscale biotechnology assists NA therapy. The specific features and challenges of various nanocarriers in clinical and preclinical studies are summarized and discussed. With the help of advanced nanoscale biotechnology, some of the major barriers to the development of NA therapy will eventually be overcome in the near future.

The current state and future directions of RNAi-based therapeutics

The RNA interference (RNAi) pathway regulates mRNA stability and translation in nearly all human cells. Small double-stranded RNA molecules can efficiently trigger RNAi silencing of specific genes, but their therapeutic use has faced numerous challenges involving safety and potency. However, August 2018 marked a new era for the field, with the US Food and Drug Administration approving patisiran, the first RNAi-based drug. In this Review, we discuss key advances in the design and development of RNAi drugs leading up to this landmark achievement, the state of the current clinical pipeline and prospects for future advances, including novel RNAi pathway agents utilizing mechanisms beyond post-translational RNAi silencing.