Reduction of inflammation in a chronic periodontitis model in rats by TNF-α gene silencing with a topically applied siRNA-loaded calcium phosphate paste

Tailoring Biomaterials Ameliorate Inflammatory Bone Loss

Inflammatory diseases, such as rheumatoid arthritis, periodontitis, chronic obstructive pulmonary disease, and celiac disease, disrupt the delicate balance between bone resorption and formation, leading to inflammatory bone loss. Conventional approaches to tackle this issue encompass pharmaceutical interventions and surgical procedures. Nevertheless, pharmaceutical interventions exhibit limited efficacy, while surgical treatments impose trauma and significant financial burden upon patients. Biomaterials show outstanding spatiotemporal controllability, possess a remarkable specific surface area, and demonstrate exceptional reactivity. In the present era, the advancement of emerging biomaterials has bestowed upon more efficacious solutions for combatting the detrimental consequences of inflammatory bone loss. In this review, the advances of biomaterials for ameliorating inflammatory bone loss are listed. Additionally, the advantages and disadvantages of various biomaterials-mediated strategies are summarized. Finally, the challenges and perspectives of biomaterials are analyzed. This review aims to provide new possibilities for developing more advanced biomaterials toward inflammatory bone loss.

Potential of oligonucleotide- and protein/peptide-based therapeutics in the management of toxicant/stressor-induced diseases

Exposure to toxicants/stressors has been linked to the development of many human diseases. They could affect various cellular components, such as DNA, proteins, lipids, and non-coding RNAs (ncRNA), thereby triggering various cellular pathways, particularly oxidative stress, inflammatory responses, and apoptosis, which can contribute to pathophysiological states. Accordingly, modulation of these pathways has been the focus of numerous investigations for managing related diseases. The involvement of various ncRNAs, such as small interfering RNA (siRNA), microRNAs (miRNA), and long non-coding RNAs (lncRNA), as well as various proteins and peptides in mediating these pathways, provides many target sites for pharmaceutical intervention. In this regard, various oligonucleotide- and protein/peptide-based therapies have been developed to treat toxicity-induced diseases, which have shown promising results in vitro and in vivo. This comprehensive review provides information about various aspects of toxicity-related diseases including their causing factors, main underlying mechanisms and intermediates, and their roles in pathophysiological states. Particularly, it highlights the principles and mechanisms of oligonucleotide- and protein/peptide-based therapies in the treatment of toxicity-related diseases. Furthermore, various issues of oligonucleotides and proteins/peptides for clinical usage and potential solutions are discussed.

Dual siRNA-Loaded Cell Membrane Functionalized Matrix Facilitates Bone Regeneration with Angiogenesis and Neurogenesis

Vascularization and innervation play irreplaceable roles in bone regeneration and bone defect repair. However, the reconstruction of blood vessels and neural networks is often neglected in material design. This study aims to design a genetically functionalized matrix (GFM) and enable it to regulate angiogenesis and neurogenesis to accelerate the process of bone defect repair. The dual small interfering RNA (siRNA)-polyvinylimide (PEI) (siRP) complexes that locally knocked down soluble vascular endothelial growth factor receptor 1 (sFlt-1) and p75 neurotrophic factor receptor (p75NTR ) are prepared. The hybrid cell membrane (MM) loaded siRP is synthesized as siRNA@MMs to coat on polylactone (PCL) electrospun fibers for mimicking the natural bone matrix. The results indicates that siRNA@MMs could regulate the expression of vascular-related and neuro-related cytokines secreted by mesenchymal stem cells (MSCs). GFMs promote the expression of osteogenic differentiation through paracrine function in vitro. GFMs attenuates inflammation and promotes osseointegration by regulating the coupling of vascularization and innervation in vivo. This study uses the natural hybrid cell membrane to carry genetic material and assist in the vascularization and innervation function of two siRNA. The results present the significance of neuro-vascularized organoid bone and may provide a promising choice for the design of bone tissue engineering scaffold.

Tissue engineering at the dentin-pulp interface using human treated dentin scaffolds conditioned with DMP1 or BMP2 plasmid DNA-carrying calcium phosphate nanoparticles

Hard dental tissue pathologies, such as caries, are conventionally managed through replacement by tooth-colored inert biomaterials. Tissue engineering provides novel treatment approaches to regenerate lost dental tissues based on bioactive materials and/or signaling molecules. While regeneration in the form of reparative dentin (osteo-dentin) is feasible, the recapitulation of the tubular microstructure of ortho-dentin and its special features is sidelined. This study characterized in vitro, and in vivo human EDTA-treated, freeze-dried dentin matrices (HTFD scaffolds) conditioned with calcium phosphate nanoparticles (NPs) bearing plasmids encoding dentinogenesis-inducing factors (pBMP2/NPs or pDMP1/NPs). The uptake and transfection efficiency of the synthesized NPs on dental pulp stem cells (DPSCs) increased in a concentration- and time-dependent manner, as evaluated qualitatively by confocal laser microscopy and transmission electron microscopy, and quantitatively by flow cytometry, while, in parallel, cell viability decreased. HTFD scaffolds conditioned with the optimal transfectability-to-viability concentration at 4 µg Ca/mL of each of the pBMP2/NPs or pDMP1/NPs preserved high levels of cell viability, evidenced by live/dead staining in vitro and caused no adverse reactions after implantation on C57BL6 mice in vivo. HTFD/NPs constructs induced rapid and pronounced odontogenic shift of the DPSCs, as evidenced by relevant gene expression patterns of RunX2, ALP, BGLAP, BMP-2, DMP-1, DSPP by real-time PCR, and acquirement of polarized meta-mitotic phenotype with cellular protrusions entering the dentinal tubules as visualized by scanning electron microscopy. Taken together, HTFD/NPs constitute a promising tool for customized reconstruction of the ortho-dentin/odontoblastic layer barrier and preservation of pulp vitality. STATEMENT OF SIGNIFICANCE: In clinical dentistry, the most common therapeutic approach for the reconstruction of hard dental tissue defects is the replacement by resin-based restorative materials. Even modern bioactive materials focus on reparative dentinogenesis, leading to amorphous dentin-bridge formation in proximity to the pulp. Therefore, the natural microarchitecture of tubular ortho-dentin is not recapitulated, and the sensory and defensive role of odontoblasts is sidelined. This study approaches the reconstruction at the dentin-pulp interface using a construct of human treated dentin (HTFD) scaffold and plasmid-carrying nanoparticles (NPs) encoding dentinogenic factors (DMP-1 or BMP-2) with excellent in vitro and in vivo properties. As a future perspective, the HTFD/NPs constructs could act as bio-fillings for personalized reconstruction of the dentin-pulp interface.

Lactobacillus reuteri for chronic periodontitis: focus on underlying mechanisms and future perspectives

Chronic periodontitis is a common oral disorder caused by pathogenic bacteria. Despite the wide use of antibiotics as the conventional adjunctive treatment, the challenges of increased antibiotic resistance and limited therapeutic effect receive considerable attention and the developments of alternative treatments gain increasing consideration. Growing evidence showed that Lactobacillus reuteri (LR) may represent a promising alternative adjunct for chronic periodontitis. It can attenuate inflammation and reduce tissue disruption. LR-assisted treatment has been shown to be effective and relatively safe in multiple clinical trials, and accumulating evidence suggests its significant biological roles. In the current review, we focus on capturing the underlying mechanisms of LR involved in chronic periodontitis, thereby representing a scientific foundation for LR-assisted therapy. Furthermore, we point out the challenges and future directions for further clinical trials to improve the clinical applicability for LR.

Endothelial cell-targeting, ROS-ultrasensitive drug/siRNA co-delivery nanocomplexes mitigate early-stage neutrophil recruitment for the anti-inflammatory treatment of myocardial ischemia reperfusion injury

Neutrophils serve as a key contributor to the pathophysiology of myocardial ischemia reperfusion injury (MIRI), because the unregulated activation and infiltration of neutrophils lead to overwhelming inflammation in the myocardium to cause tissue damage. Herein, endothelial cell-targeting and  reactive oxygen species (ROS)-ultrasensitive nanocomplexes (NCs) were developed to mediate efficient co-delivery of VCAM-1 siRNA (siVCAM-1) and dexamethasone (DXM), which cooperatively inhibited neutrophil recruitment by impeding neutrophil migration and adhesion. RPPT was first synthesized via crosslinking of PEI 600 with ditellurium followed by modification with PEG and the endothelial cell-targeting peptide cRGD. RPPT was allowed to envelope the DXM-loaded PLGA nanoparticles and condense the siVCAM-1. After systemic administration in rats experiencing MIRI, the cRGD-modified NCs efficiently targeted and entered the inflamed endothelial cells, wherein RPPT was sensitively degraded by over-produced ROS to trigger intracellular siVCAM-1 release and potentiate the VCAM-1 silencing efficiency. As a consequence of the complementary function of DXM and siVCAM-1, the NCs notably mitigated neutrophil infiltration into ischemic myocardium, provoking potent anti-inflammatory efficacy to reduce MIRI and recover cardiac function. The present study offers an effective approach for the controlled co-delivery of siRNA and drug cargoes, and it also highlights the importance of multi-dimensional manipulation of neutrophils in anti-inflammatory treatment. STATEMENT OF SIGNIFICANCE: The unregulated activation and infiltration of neutrophils lead to overwhelming inflammation in the myocardium after myocardial ischemia reperfusion injury (MIRI). Here, endothelial cell-targeting and ROS-ultrasensitive nanocomplexes (NCs), comprised of PLGA NPs decorated with cRGD-poly(ethylene glycol) (PEG)-modified, ditellurium-crosslinked PEI (RPPT), were developed to mediate efficient co-delivery of VCAM-1 siRNA (siVCAM-1) and dexamethasone (DXM). DXM and siVCAM-1 with complementary functions inhibited both the migration and adhesion of neutrophils, efficiently interventing the neutrophil recruitment and interrupting the self-amplified inflammation cascade in the injured myocardium. The molecular design of RPPT renders an effective example for constructing polymeric materials with high ROS sensitivity, and it resolves the critical dilemma related to polycation-mediated siRNA delivery, such as siRNA encapsulation versus release, and transfection efficiency versus toxicity.

Designing electrospun fiber platforms for efficient delivery of genetic material and genome editing tools

Electrospun fibers are versatile biomaterial platforms with great potential to support regeneration. Electrospun fiber characteristics such as fiber diameter, degree of alignment, rate of degradation, and surface chemistry enable the creation of unique, tunable scaffolds for various drug or gene delivery applications. The delivery of genetic material and genome editing tools via viral and non-viral vectors are approaches to control cellular protein production. However, immunogenicity, off-target effects, and low delivery efficiencies slow the progression of gene delivery strategies to clinical settings. The delivery of genetic material from electrospun fibers overcomes such limitations by allowing for localized, tunable delivery of genetic material. However, the process of electrospinning is harsh, and care must be taken to retain genetic material bioactivity. This review presents an up-to-date summary of strategies to incorporate genetic material onto or within electrospun fiber platforms to improve delivery efficiency and enhance the regenerative potential of electrospun fibers for various tissue engineering applications.

The pathogenic mechanism of oral bacteria and treatment with inhibitors

OBJECTIVES

The objective of this study was to introduce the evidence obtained through extensive research that periodontitis increases risk of many systemic diseases.

METHOD

Analysis of some oral bacteria (P. gingivalis, T. denticola, T. forsythia, A. actinomycetemcomitans, and F. nucleatum) and its related treatments and mediators by the specific methods (western blot, ELISA, etc).

RESULTS

This article reviews in detail the evidence obtained through extensive research that periodontitis increases risk of many systemic diseases, including cardiovascular disease, rheumatoid arthritis, and Alzheimer's disease. These diseases are known to be associated with some certain specific gram-negative bacteria as periodontal pathogens, which induce inflammation and related diseases through TLR receptors, kinases, transcriptional factors and other cytokines. We also reviewed the latest research for inhibitors against inflammation and related diseases that have potential to be further applied clinically. In addition, based on a large amount of research evidence, we draw two tables about the mechanism of disease caused by periodontal bacteria, so that readers can easily search and analyze these research results.

DISCUSSION

This review details how the periodontal bacteria and their virulence factors can trigger host immune defense and induce many systemic diseases via inflammation and invasion. This Review also addressed the latest research around inhibitors against inflammation.

Non-viral nanoparticles for RNA interference: Principles of design and practical guidelines

Ribonucleic acid interference (RNAi) is an innovative treatment strategy for a myriad of indications. Non-viral synthetic nanoparticles (NPs) have drawn extensive attention as vectors for RNAi due to their potential advantages, including improved safety, high delivery efficiency and economic feasibility. However, the complex natural process of RNAi and the susceptible nature of oligonucleotides render the NPs subject to particular design principles and requirements for practical fabrication. Here, we summarize the requirements and obstacles for fabricating non-viral nano-vectors for efficient RNAi. To address the delivery challenges, we discuss practical guidelines for materials selection and NP synthesis in order to maximize RNA encapsulation efficiency and protection against degradation, and to facilitate the cytosolic release of oligonucleotides. The current status of clinical translation of RNAi-based therapies and further perspectives for reducing the potential side effects are also reviewed.

Biological and Medical Applications of Calcium Phosphate Nanoparticles

Calcium phosphate nanoparticles have a high biocompatibility and biodegradability due to their chemical similarity to human hard tissue, for example, bone and teeth. They can be used as efficient carriers for different kinds of biomolecules such as nucleic acids, proteins, peptides, antibodies, or drugs, which alone are not able to enter cells where their biological effect is required. They can be loaded with cargo molecules by incorporating them, unlike solid nanoparticles, and also by surface functionalization. This offers protection, for example, against nucleases, and the possibility for cell targeting. If such nanoparticles are functionalized with fluorescing dyes, they can be applied for imaging in vitro and in vivo. Synthesis, functionalization and cell uptake mechanisms of calcium phosphate nanoparticles are discussed together with applications in transfection, gene silencing, imaging, immunization, and bone substitution. Biodistribution data of calcium phosphate nanoparticles in vivo are reviewed.

Gene transfection achieved by utilizing antibacterial calcium phosphate nanoparticles for enhanced regenerative therapy

Protamine-coated multi-shell calcium phosphate (CaP) was developed as a non-viral vector for tissue regeneration therapy. CaP nanoparticles loaded with different amounts of plasmid DNA encoding bone morphogenetic protein 2 (BMP-2) and insulin-like growth factor 1 (IGF-1) were used to treat MC3T3E1 cells, and the yield of the released BMP-2 or IGF-1 was measured using ELISA 3 days later. Collagen scaffolds containing CaP nanoparticles were implanted into rat cranial bone defects, and BMP-2 and IGF-1 yields, bone formation, and bone mineral density enhancement were evaluated 28 days after gene transfer. The antibacterial effects of CaP nanoparticles against Streptococcus mutans and Aggregatibacter actinomycetemcomitans increased with an increase in the protamine dose, while they were lower for Staphylococcus aureus and Porphyromonas gingivalis. In the combination treatment with BMP-2 and IGF-1, the concentration ratio of BMP-2 and IGF-1 is an important factor affecting bone formation activity. The calcification activity and OCN mRNA of MC3T3E1 cells subjected to a BMP-2:IGF-1 concentration ratio of 1:4 was higher at 14 days. During gene transfection treatment, BMP-2 and IGF-1 were released simultaneously after gene transfer; the loaded dose of the plasmid DNA encoding IGF-1 did not impact the BMP-2 or IGF-1 yield or new bone formation ratio in vitro and in vivo. In conclusion, two growth factor-releasing systems were developed using an antibacterial gene transfer vector, and the relationship between the loaded plasmid DNA dose and resultant growth factor yield was determined in vitro and in vivo.

Synthesis and characterization of PLGA/HAP scaffolds with DNA-functionalised calcium phosphate nanoparticles for bone tissue engineering

Porous scaffolds of poly(lactide-co-glycolide) (PLGA; 85:15) and nano-hydroxyapatite (nHAP) were prepared by an emulsion-precipitation procedure from uniform PLGA-nHAP spheres (150-250 µm diameter). These spheres were then thermally sintered at 83 °C to porous scaffolds that can serve for bone tissue engineering or for bone substitution. The base materials PLGA and nHAP and the PLGA-nHAP scaffolds were extensively characterized by X-ray powder diffraction, infrared spectroscopy, thermogravimetry, differential scanning calorimetry, and scanning electron microscopy. The scaffold porosity was about 50 vol% as determined by relating mass and volume of the scaffolds, together with the computed density of the solid phase (PLGA-nHAP). The cultivation of HeLa cells demonstrated their high cytocompatibility. In combination with DNA-loaded calcium phosphate nanoparticles, they showed a good activity of gene transfection with enhanced green fluorescent protein (EGFP) as model protein. This is expected enhance bone growth around an implanted scaffold or inside a scaffold for tissue engineering.

A pH-sensitive fluorescent protein sensor to follow the pathway of calcium phosphate nanoparticles into cells

Calcium phosphate nanoparticles (100 nm) were fluorescently labelled with poly(ethyleneimine) (PEI_ATTO490LS; red fluorescence). They were loaded with a Tandem fusion protein consisting of mRFP1-eGFP (red and green fluorescence in the same molecule)that acts as smart biological pH sensor to trace nanoparticles inside cells. Its fluorescence is also coupled to the structural integrity of the protein, i.e. it is also a label for a successful delivery of a functional protein into the cell. At pH 7.4, the fluorescence of both proteins (red and green) is detectable. At a pH of 4.5-5 inside the lysosomes, the green fluorescence is quenched due to the protonation of the eGFP chromophore, but the pH-independent red fluorescence of mRFP1 remains. The nanoparticles were taken up by cells (cell lines: HeLa, Caco-2 and A549) via endocytic pathways and then directed to lysosomes. Time-resolved confocal laser scanning microscopy confirmed mRFP1 and nanoparticles co-localizing with lysosomes. The fluorescence of eGFP was only detectable outside lysosomes, i.e. most likely inside early endosomes or at the cell membrane during the uptake, indicating the neutral pH at these locations. The Tandem fusion protein provides a versatile platform to follow the intracellular pathway of bioactive nanocarriers, e.g. therapeutic proteins. The transfection with a Tandem-encoding plasmid by calcium phosphate nanoparticles led to an even intracellular protein distribution in cytosol and nucleoplasm, i.e. very different from direct protein uptake. Neither dissolved protein nor dissolved plasmid DNA were taken up by the cells, underscoring the necessity for a suitable carrier like a nanoparticle. STATEMENT OF SIGNIFICANCE: A pH-sensitive protein ("tandem") was used to follow the pathway of calcium phosphate nanoparticles. This protein consists of a pH-sensitive fluorophore (eGFP; green) and a pH-independent fluorophore (mRFP1; red). This permits to follow the pathway of a nanoparticle inside a cell. At a low pH inside an endolysosome, the green fluorescence vanishes but the red fluorescence persists. This is also a very useful model for the delivery of therapeutic proteins into cells. The delivery by nanoparticles was compared with the protein expression after cell transfection with plasmid DNA encoding for the tandem protein. High-resolution image analysis gave quantitative data on the intracellular protein distribution.

Involvement of Cathepsins in Innate and Adaptive Immune Responses in Periodontitis

Periodontitis is an infectious disease whereby the chronic inflammatory process of the periodontium stimulated by bacterial products induces specific host cell responses. The activation of the host cell immune system upregulates the production of inflammatory mediators, comprising cytokines and proteolytic enzymes, which contribute to inflammation and bone destruction. It has been well known that periodontitis is related to systemic inflammation which links to numerous systemic diseases, including diabetes and arteriosclerosis. Furthermore, periodontitis has been reported in association with neurodegenerative diseases such as Alzheimer's disease (AD) in the brain. Regarding immune responses and inflammation, cathepsin B (CatB) plays pivotal role for the induction of IL-1β, cathepsin K- (CatK-) dependent active toll-like receptor 9 (TLR9) signaling, and cathepsin S (CatS) which involves in regulating both TLR signaling and maturation of the MHC class II complex. Notably, both the production and proteolytic activities of cathepsins are upregulated in chronic inflammatory diseases, including periodontitis. In the present review, we focus on the roles of cathepsins in the innate and adaptive immune responses within periodontitis. We believe that understanding the roles of cathepsins in the immune responses in periodontitis would help to elucidate the therapeutic strategies of periodontitis, thus benefit for reduction of systemic diseases as well as neurodegenerative diseases in the global aging society.