Biodegradable polymers: an update on drug delivery in bone and cartilage diseases

Effective strategies to enhance the diagnosis and treatment of RCC: The application of biocompatible materials

Renal cell carcinoma (RCC) is recognized as one of the three primary malignant tumors affecting the urinary system, posing a significant risk to human health and life. Despite advancements in understanding RCC, challenges persist in its diagnosis and treatment, particularly in early detection and diagnosis due to issues of low specificity and sensitivity. Consequently, there is an urgent need for the development of effective strategies to enhance diagnostic accuracy and treatment outcomes for RCC. In recent years, with the extensive research on materials for applications in the biomedical field, some materials have been identified as promising for clinical applications, e.g., in the diagnosis and treatment of many tumors, including RCC. Herein, we summarize the latest materials that are being studied and have been applied in the early diagnosis and treatment of RCC. While focusing on their adjuvant effects, we also discuss their technical principles and safety, thus highlighting the value and potential of their application. In addition, we also discuss the limitations of the application of these materials and possible future directions, providing new insights for improving RCC diagnosis and treatment.

Polygonatum sibiricum polysaccharides protect against knee osteoarthritis by inhibiting the TLR2/NF-κB signaling pathway in vivo and in vitro

Polygonatum sibiricum polysaccharides (PSP), the primary constituent of Polygonatum sibiricum, have been shown to exhibit a wide range of pharmacological effects, but their impact on osteoarthritis (OA) remains unclear. The objective of this study was to investigate the protective effects of PSP against OA and to elucidate its underlying molecular mechanism. In our in vitro experiments, PSP not only inhibited the IL-1β-induced inflammatory responses and the nuclear factor kappa-B (NF-κB) signaling pathway in chondrocytes but also regulated the cartilage matrix metabolism. In addition, we detected 394 significantly differentially expressed genes through RNA-seq analysis on PSP-intervened chondrocytes, and the toll-like receptor 2 (TLR2) was identified as the most important feature by functional network analysis and qRT-PCR. It was also revealed that PSP treatment significantly reversed the IL-1-induced up-regulation of TLR2 expression in chondrocytes, while TLR2 overexpression partially inhibited the regulatory effects of PSP on inflammation, NF-κB signaling pathway and matrix metabolism. In our in vivo experiments, PSP treatment alleviated the development of destabilization of medial meniscus (DMM)-induced OA in mouse knee joints, inhibited the DMM-induced activation of the TLR2/NF-κB signaling pathway in mouse knee joint cartilage, and reduced the serum levels of inflammatory cytokines. In conclusion, PSP exerts its anti-inflammatory, matrix synthesis-promoting and matrix catabolism-suppressing effects in knee OA by inhibiting the TLR2/NF-κB signaling pathway, suggesting that PSP may be potentially targeted as a novel all-natural, low-toxicity drug for OA prevention and treatment.

Prospects of Disease-Modifying Osteoarthritis Drugs

Osteoarthritis (OA) causes a massive disease burden with a global prevalence of nearly 23% in 2020 and an unmet need for adequate treatment, given a lack of disease-modifying drugs (DMOADs). The author reviews the prospects of active DMOAD candidates in the phase 2/3 clinical trials of drug development pipeline based on key OA pathogenetic mechanisms directed to inflammation-driven, bone-driven, and cartilage-driven endotypes. The challenges and possible research opportunities are stated in terms of the formulation of a research question known as the PICO approach: (1) population, (2) interventions, (3) comparison or placebo, and (4) outcomes.

Antibacterial and Osteogenic Dual-Functional Micronano Composite Scaffold Fabricated via Melt Electrowriting and Solution Electrospinning for Bone Tissue Engineering

The utilization of micronano composite scaffolds has been extensively demonstrated to confer the superior advantages in bone repair compared to single nano- or micron-sized scaffolds. Nevertheless, the enhancement of bioactivities within these composite scaffolds remains challenging. In this study, we propose a novel approach to combine melt electrowriting (MEW) and solution electrospinning (SES) techniques for the fabrication of a composite scaffold incorporating hydroxyapatite (HAP), an osteogenic component, and roxithromycin (ROX), an antibacterial active component. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) confirmed the hierarchical architecture of the nanofiber-microgrid within the scaffold, as well as the successful loading of HAP and ROX. The incorporation of HAP enhanced the water absorption capacity of the composite scaffold, thus promoting cell adhesion and proliferation, as well as osteogenic differentiation. Furthermore, ROX resulted in effective antibacterial capability without any observable cytotoxicity. Finally, the scaffolds were applied to a rat calvarial defect model, and the results demonstrated that the 20% HAP group exhibited superior new bone formation without causing adverse reactions. Therefore, our findings present a promising strategy for designing and fabricating bioactive scaffolds for bone regeneration.

Sargassum polysaccharide attenuates osteoarthritis in rats and is associated with the up-regulation of the ITGβ1-PI3K-AKT signaling pathway

Background

Osteoarthritis (OA) presents a formidable challenge, characterized by as-yet-unclear mechanical intricacies within cartilage and the dysregulation of bone homeostasis. Our preliminary data revealed the encouraging potential of a Sargassum polysaccharide (SP), in promoting chondrogenesis. The aim of our study is to comprehensively assess the therapeutic effects of SP on OA models and further elucidate its potential mechanism.

Methods

The protective effects of SP were initially evaluated in an inflammation-induced human chondrocyte (C28) cell model. CCK-8 assays, Alcian blue staining, RT-qPCR and Western blotting were used to verify the chondrogenesis of SP in vitro. To assess the efficacy of SP in vivo, surgically induced medial meniscus destabilization (DMM) OA rats underwent an 8-week SP treatment. The therapeutic effects of SP in OA rats were comprehensively evaluated using X-ray imaging, micro-computed tomography (μ-CT), histopathological analysis, as well as immunohistochemical and immunofluorescent staining. Following these assessments, we delved into the potential signaling pathways of SP in inflammatory chondrocytes utilizing RNA-seq analysis. Validation of these findings was conducted through RT-qPCR and western blotting techniques.

Results

SP significantly enhance the viability of C28 chondrocytes, and increased the secretion of acidic glycoproteins. Moreover, SP stimulated the expression of chondrogenic genes (Aggrecan, Sox9, Col2a1) and facilitated the synthesis of Collagen II protein in C28 inflammatory chondrocytes. In vivo experiments revealed that SP markedly ameliorated knee joint stenosis, alleviated bone and cartilage injuries, and reduced the histopathological scores in the OA rats. μ-CT analysis confirmed that SP lessened bone impairments in the medial femoral condyle and the subchondral bone of the tibial plateau, significantly improving the microarchitectural parameters of the subchondral bone. Histopathological analyses indicated that SP notably enhanced cartilage quality on the surface of the tibial plateau, leading to increased cartilage thickness and area. Immunohistochemistry staining and immunofluorescence staining corroborated these findings by showing a significant promotion of Collagen II expression in OA joints treated with SP. RNA-seq analysis suggest that SP's effects were mediated through the regulation of the ITGβ1-PI3K-AKT signaling axis, thereby stimulating chondrogenesis. Verification through RT-qPCR and Western blot analyses confirmed that SP significantly upregulated the expression of ITGβ1, p110δ, AKT1, ACAN, and Col2a1. Notably, knock-down of ITGβ1 using siRNA in C28 chondrocytes inhibited the expression of ITGβ1, p110δ, AKT1, and ACAN. However, these inhibitory effects were not completely reversed by supplemental SP intervention.

Conclusions

In summary, our findings reveal that SP significantly enhances chondrogenesis both in vitro and in vivo, alleviating OA progression both in bone and cartilage. The observed beneficial effects are intricately linked to the activation of the ITGβ1-PI3K-AKT signaling axis.

The translational potential of this article

Our research marks the first instance unveiling the advantageous effects and underlying mechanisms of SP in OA treatment. With its clinical prospects, SP presents compelling new evidence for the advancement of a next-generation polysaccharide drug for OA therapy.

Exploring the translational potential of PLGA nanoparticles for intra-articular rapamycin delivery in osteoarthritis therapy

Osteoarthritis (OA) is a prevalent joint disease that affects all the tissues within the joint and currently lacks disease-modifying treatments in clinical practice. Despite the potential of rapamycin for OA disease alleviation, its clinical application is hindered by the challenge of achieving therapeutic concentrations, which necessitates multiple injections per week. To address this issue, rapamycin was loaded into poly(lactic-co-glycolic acid) nanoparticles (RNPs), which are nontoxic, have a high encapsulation efficiency and exhibit sustained release properties for OA treatment. The RNPs were found to promote chondrogenic differentiation of ATDC5 cells and prevent senescence caused by oxidative stress in primary mouse articular chondrocytes. Moreover, RNPs were capable to alleviate metabolism homeostatic imbalance of primary mouse articular chondrocytes in both monolayer and 3D cultures under inflammatory or oxidative stress. In the mouse destabilization of the medial meniscus (DMM) model, intra-articular injection of RNPs effectively mitigated joint cartilage destruction, osteophyte formation, chondrocytes hypertrophy, synovial inflammation, and pain. Our study demonstrates the feasibility of using RNPs as a potential clinically translational therapy to prevent the progression of post-traumatic OA.

Drug Delivery and Therapy Strategies for Osteoporosis Intervention

With the advent of the aging society, osteoporosis (OP) risk increases yearly. Currently, the clinical usage of anti-OP drugs is challenged by recurrent side effects and poor patient compliance, regardless of oral, intravenous, or subcutaneous administration. Properly using a drug delivery system or formulation strategy can achieve targeted drug delivery to the bone, diminish side effects, improve bioavailability, and prolong the in vivo residence time, thus effectively curing osteoporosis. This review expounds on the pathogenesis of OP and the clinical medicaments used for OP intervention, proposes the design approach for anti-OP drug delivery, emphatically discusses emerging novel anti-OP drug delivery systems, and enumerates anti-OP preparations under clinical investigation. Our findings may contribute to engineering anti-OP drug delivery and OP-targeting therapy.

Size-Dependent Polymeric Nanoparticle Distribution in a Static versus Dynamic Microfluidic Blood Vessel Model: Implications for Nanoparticle-Based Drug Delivery

Nanoparticles (NPs) have been widely investigated in the nanomedicine field. One of the main challenges is to accurately predict the NP distribution and fate after administration. Microfluidic platforms acquired huge importance as tools to model the in vivo environment. In this study, we leveraged a microfluidic platform to produce FITC-labeled poly(lactide-co-glycolide)-block-poly(ethylene glycol) (PLGA-PEG) NPs with defined sizes of 30, 50, and 70 nm. The study aimed to compare the ability of NPs with differences of 20 nm in size to cross an endothelial barrier using static (Transwell inserts) and dynamic (microfluidic perfusion device) in vitro models. Our results evidence a size-dependent NP crossing in both models (30 > 50 > 70 nm) and highlight the bias deriving from the static model, which does not involve shear stresses. The permeation of each NP size was significantly higher in the static system than in the dynamic model at the earliest stages. However, it gradually decreased to levels comparable with those of the dynamic model. Overall, this work highlights clear differences in NP distribution over time in static versus dynamic conditions and distinct size-dependent patterns. These findings reinforce the need for accurate in vitro screening models that allow for more accurate predictions of in vivo performance.

Combinational System of Lipid-Based Nanocarriers and Biodegradable Polymers for Wound Healing: An Updated Review

Skin wounds have imposed serious socioeconomic burdens on healthcare providers and patients. There are just more than 25,000 burn injury-related deaths reported each year. Conventional treatments do not often allow the re-establishment of the function of affected regions and structures, resulting in dehydration and wound infections. Many nanocarriers, such as lipid-based systems or biobased and biodegradable polymers and their associated platforms, are favorable in wound healing due to their ability to promote cell adhesion and migration, thus improving wound healing and reducing scarring. Hence, many researchers have focused on developing new wound dressings based on such compounds with desirable effects. However, when applied in wound healing, some problems occur, such as the high cost of public health, novel treatments emphasizing reduced healthcare costs, and increasing quality of treatment outcomes. The integrated hybrid systems of lipid-based nanocarriers (LNCs) and polymer-based systems can be promising as the solution for the above problems in the wound healing process. Furthermore, novel drug delivery systems showed more effective release of therapeutic agents, suitable mimicking of the physiological environment, and improvement in the function of the single system. This review highlights recent advances in lipid-based systems and the role of lipid-based carriers and biodegradable polymers in wound healing.

A review focusing on the benefits of plant-derived polysaccharides for osteoarthritis

Osteoarthritis (OA) is a chronic joint disease characterized by progressive cartilage degeneration, which imposes a heavy physical and financial burden on the middle-aged and elderly population. As the pathogenesis of OA has not been fully elucidated, it is of great importance to develop targeted therapeutic or preventive medications. Traditional therapeutic drugs, such as non-steroidal anti-inflammatory drugs, steroids and opioids, have significant side effects, making the exploration for safe and effective alternative therapeutic drugs urgent. In recent years, many studies have reported the role of plant-derived polysaccharides in anti-inflammation, anti-oxidation, regulation of chondrocyte metabolism and proliferation, and cartilage protection, and have demonstrated their great potential in the treatment of OA. Therefore, by focusing on studies related to the intervention of plant-derived polysaccharides in OA, including in vivo and in vitro experiments, this review aimed to classify and summarize the existing research findings according to different mechanisms of action. In addition, reports on plant-derived polysaccharides as nanoparticles were also explored. Then, candidate monomers and theoretical bases were provided for the further development and application of novel drugs in the treatment of OA.

Injectable Drug Delivery Systems for Osteoarthritis and Rheumatoid Arthritis

Joint diseases are one of the most common causes of morbidity and disability worldwide. The main diseases that affect joint cartilage are osteoarthritis and rheumatoid arthritis, which require chronic treatment focused on symptomatic relief. Conventional drugs administered through systemic or intra-articular routes have low accumulation and/or retention in articular cartilage, causing dose-limiting toxicities and reduced efficacy. Therefore, there is an urgent need to develop improved strategies for drug delivery, in particular, the use of micro- and nanotechnology-based methods. Encapsulation of therapeutic agents in delivery systems reduces drug efflux from the joint and protects against rapid cellular and enzymatic clearance following intra-articular injection. Consequently, the use of drug delivery systems decreases side effects and increases therapeutic efficacy due to enhanced drug retention in the intra-articular space. Additionally, the frequency of intra-articular administration is reduced, as delivery systems enable sustained drug release. This review summarizes various advanced drug delivery systems, such as nano- and microcarriers, developed for articular cartilage diseases.

Role of Nanomaterials in COVID-19 Prevention, Diagnostics, Therapeutics, and Vaccine Development

Facing the deadly pandemic caused by the SARS-CoV-2 virus all over the globe, it is crucial to devote efforts to fighting and preventing this infectious virus. Nanomaterials have gained much attention after the approval of lipid nanoparticle-based COVID-19 vaccines by the United States Food and Drug Administration (USFDA). In light of increasing demands for utilizing nanomaterials in the management of COVID-19, this comprehensive review focuses on the role of nanomaterials in the prevention, diagnostics, therapeutics, and vaccine development of COVID-19. First, we highlight the variety of nanomaterials usage in the prevention of COVID-19. We discuss the advantages of nanomaterials as well as their uses in the production of diagnostic tools and treatment methods. Finally, we review the role of nanomaterials in COVID-19 vaccine development. This review offers direction for creating products based on nanomaterials to combat COVID-19.

Botanical Drug Extracts Combined With Biomaterial Carriers for Osteoarthritis Cartilage Degeneration Treatment: A Review of 10 Years of Research

Osteoarthritis (OA) is a long-term chronic arthrosis disease which is usually characterized by pain, swelling, joint stiffness, reduced range of motion, and other clinical manifestations and even results in disability in severe cases. The main pathological manifestation of OA is the degeneration of cartilage. However, due to the special physiological structure of the cartilage, once damaged, it is unable to repair itself, which is one of the challenges of treating OA clinically. Abundant studies have reported the application of cartilage tissue engineering in OA cartilage repair. Among them, cell combined with biological carrier implantation has unique advantages. However, cell senescence, death and dedifferentiation are some problems when cultured in vitro. Botanical drug remedies for OA have a long history in many countries in Asia. In fact, botanical drug extracts (BDEs) have great potential in anti-inflammatory, antioxidant, antiaging, and other properties, and many studies have confirmed their effects. BDEs combined with cartilage tissue engineering has attracted increasing attention in recent years. In this review, we will explain in detail how cartilage tissue engineering materials and BDEs play a role in cartilage repair, as well as the current research status.

Rapamycin-loaded Poly(lactic-co-glycolic) acid nanoparticles: Preparation, characterization, and in vitro toxicity study for potential intra-articular injection

Osteoarthritis (OA) is the most common degenerative joint disease. Rapamycin is a potential candidate for OA treatment by increasing the autophagy process implicated in its physiopathology. To optimize Rapamycin profit and avoid systemic side effects, intra-articular (i.a.) administration appeared helpful. However, Rapamycin's highly hydrophobic nature and low bioavailability made it challenging to develop purpose-made drug delivery systems to overcome these limitations. We developed Rapamycin-loaded nanoparticles (NPs) using poly (lactic-co-glycolic acid) by emulsion/evaporation method. We evaluated these NPs' cytocompatibility towards cartilage (chondrocytes) and synovial membrane cells (synoviocytes) for a potential i.a. administration. The in vitro characterization of Rapamycin-loaded NPs had shown a suitable profile for an i.a. administration. In vitro biocompatibility of NPs was highlighted to 10 µM of Rapamycin for both synoviocytes and chondrocytes, but significant toxicity was observed with higher concentrations. Besides, synoviocytes are more sensitive to Rapamycin-loaded NPs than chondrocytes. Finally, we observed in vitro that an adapted formulated Rapamycin-loaded NPs could be safe at suitable i.a. injection concentrations. The toxic effect of Rapamycin encapsulated in these NPs on both articular cells was dose-dependent. After Rapamycin-loaded NPs i.a. administration, local retention, in situ safety, and systemic release should be evaluated with experimental in vivo models.

The optimized drug delivery systems of treating cancer bone metastatic osteolysis with nanomaterials

Some cancers such as human breast cancer, prostate cancer, and lung cancer easily metastasize to bone, leading to osteolysis and bone destruction accompanied by a complicated microenvironment. Systemic administration of bisphosphonates (BP) or denosumab is the routine therapy for osteolysis but with non-negligible side effects such as mandibular osteonecrosis and hypocalcemia. Thus, it is imperative to exploit optimized drug delivery systems, and some novel nanotechnology and nanomaterials have opened new horizons for scientists. Targeted and local drug delivery systems can optimize biodistribution depending on nanoparticles (NPs) or microspheres (MS) and implantable biomaterials with the controllable property. Drug delivery kinetics can be optimized by smart and sustained/local drug delivery systems for responsive delivery and sustained delivery. These delicately fabricated drug delivery systems with special matrix, structure, morphology, and modification can minimize unexpected toxicity caused by systemic delivery and achieve desired effects through integrating multiple drugs or multiple functions. This review summarized recent studies about optimized drug delivery systems for the treatment of cancer metastatic osteolysis, aimed at giving some inspiration in designing efficient multifunctional drug delivery systems.

Cellular Uptake of Three Different Nanoparticles in an Inflammatory Arthritis Scenario versus Normal Conditions

Nanoparticles (NPs) have wide potential applications in the biomedical field. To promote targeted and controlled delivery of encapsulated drugs, it is fundamentally important to understand the factors regulating NP uptake by different cells. Thus, the goal of the present study is to assess the internalization rates of different NPs under normal and proinflammatory states in primary human articular chondrocytes (hACs), human umbilical vein endothelial cells (EA), and human monocytes (THP-1). Here, we compared chitosan-hyaluronic acid (Ch-HA) polymeric NPs, methoxypolyethylene glycol amine-glutathione-palmitic acid (mPEG-GSH_n-PA) micelles, and cholesterol/l-α-phosphatidylcholine/DSPE-PEG-Mal (Chol/EPC/DSPE-PEG-Mal) unilamellar liposomes (LUVs). Our results reveal the importance of surface charge and chemistry in determining the levels of NP internalization. Under normal conditions, the cellular uptake was ≈30% for Ch-HA NPs and ≈100% for mPEG-GSH_n-PA micelles and Chol/EPC/DSPE-PEG-Mal LUVs. A proinflammatory cell state promoted a higher uptake of the Ch-HA NPs by EA cells (93% after 24 h). Since the therapeutic efficacy of the NP-loaded cargo is dependent on trafficking routes after cellular internalization, we tested their internalization pathways. Accordingly, caveolae-mediated endocytosis or energy-independent non-endocytic pathways, which circumvent lysosomal degradation, were accomplished in hACs and EA by LUVs and in M1 polarized macrophages by micelles. The present outcomes highlight the importance of considering cellular uptake and internalization pathways by the target cell when designing functional NPs for therapeutic applications.

Biomimetic and cell-based nanocarriers - New strategies for brain tumor targeting

In the last two decades no significant advances were achieved in the treatment of the most frequent and malignant types of brain tumors. The main difficulties in achieving progress are related to the incapacity to deliver drugs in therapeutic amounts into the central nervous system and the associated severe side effects. Indeed, to obtain effective treatments, the drugs should be able to cross the intended biological barriers and not being inactivated before reaching the specific therapeutic target. To overcome these challenges the development of synthetic nanocarriers has been widely explored for brain tumor treatment but unfortunately with no clinical translation until date. The use of cell-derived nanocarriers or biomimetic nanocarriers has been studied in the last few years, considering their innate bio-interfacing properties. The ability to carry therapeutic agents and a higher selectivity towards brain tumors would bring new hope for the development of safe and effective treatments. In this review, we explore the biological barriers that need to be crossed for effective delivery in brain tumors, and the types and properties of cell-based nanocarriers (extracellular vesicles and cell-membrane coated nanocarriers) currently under investigation.

Glutathione Reductase-Sensitive Polymeric Micelles for Controlled Drug Delivery on Arthritic Diseases

Inflammation plays an essential role in arthritis development and progression. Despite the advances in the pharmaceutical field, current treatments still present low efficacy and severe side effects. Considering the high activity of the glutathione reductase (GR) enzyme in inflamed joints, a distinctive drug delivery system sensitive to the GR enzyme was designed for efficient drug delivery on arthritic diseases. A linear amphiphilic polymer composed of methoxypolyethylene glycol amine-glutathione-palmitic acid (mPEG-GSH_n-PA) was synthesized and the intermolecular oxidation of the thiol groups from GSHs retain the drug inside the resulting micelles. Stable polymeric micelles of 100 nm of size presented a loading capacity of dexamethasone (Dex) up to 65%. Although in physiological conditions the Dex release presented slow and sustained kinetics, in the presence of the GR enzyme, there was a burst release (stimuli-responsive properties). Biological assays demonstrated their cytocompatibility in contact with human articular chondrocytes, macrophages, and endothelial cells as well as their hemocompatibility. Importantly, in an in vitro model of inflammation, the polymeric micelles promoted a controlled drug release in the presence of GR, exhibiting a higher efficacy than the free Dex while reducing the negative effects of the drug into normal cells. In conclusion, this formulation is a promising approach to treat arthritic diseases and other inflammatory conditions.

Modulating inflammation through the neutralization of Interleukin-6 and tumor necrosis factor-α by biofunctionalized nanoparticles

Biological agents that neutralize the activity of pro-inflammatory cytokines are revolutionizing the treatment of inflammatory conditions. However, the antibodies (Abs) short half-life and off-target distribution critically limit their efficacy and safety. Therefore, this work proposes the immobilization of anti-TNF-α and anti-IL-6 Abs at the surface of polymeric nanoparticles (NPs) in order to extend and increase the Abs therapeutic efficacy, owing to the protection from degradation that the NPs provide, and to avoid off-target side effects through local administration. In an in vitro model of inflammation, biofunctionalized NPs were able to reduce the harmful effects on human chondrocytes provided by inflammatory macrophages, being demonstrated the additive effects of the dual neutralization. Significantly, biofunctionalized NPs ameliorated inflammation more efficiently than soluble Abs in an in vivo experimental model of inflammation, exhibiting a safe profile, a prolonged action, and a stronger efficacy. Hence, as this strategy is able to increase the therapeutic efficacy of the currently available treatments, it is a promising potential therapeutic option for inflammatory conditions.

Chronic Inflammatory Diseases, Anti-Inflammatory Agents and Their Delivery Nanosystems

Inflammatory diseases, whether caused by excessive stress on certain tissues/parts of the body or arising from infections accompanying autoimmune or secondary diseases, have become a problem, especially in the Western world today. Whether these are inflammations of visceral organs, joints, bones, or the like, they are always a physiological reaction of the body, which always tries to eradicate noxious agents and restore tissue homeostasis. Unfortunately, this often results in damage, often irreversible, to the affected tissues. Nevertheless, these inflammatory reactions of the body are the results of excessive stress, strain, and the generally unhealthy environment, in which the people of Western civilization live. The pathophysiology and pathobiochemistry of inflammatory/autoimmune processes are being studied in deep detail, and pharmaceutical companies are constantly developing new drugs that modulate/suppress inflammatory responses and endogenous pro-inflammatory agents. In addition to new specifically targeted drugs for a variety of pro-inflammatory agents, a strategy can be found for the use of older drugs, which are formulated into special nanodrug delivery systems with targeted distribution and often modified release. This contribution summarizes the current state of research and development of nanoformulated anti-inflammatory agents from both conventional drug classes and experimental drugs or dietary supplements used to alleviate inflammatory reactions.

Adjuvant Drug-Assisted Bone Healing: Advances and Challenges in Drug Delivery Approaches

Bone defects of critical size after compound fractures, infections, or tumor resections are a challenge in treatment. Particularly, this applies to bone defects in patients with impaired bone healing due to frequently occurring metabolic diseases (above all diabetes mellitus and osteoporosis), chronic inflammation, and cancer. Adjuvant therapeutic agents such as recombinant growth factors, lipid mediators, antibiotics, antiphlogistics, and proangiogenics as well as other promising anti-resorptive and anabolic molecules contribute to improving bone healing in these disorders, especially when they are released in a targeted and controlled manner during crucial bone healing phases. In this regard, the development of smart biocompatible and biostable polymers such as implant coatings, scaffolds, or particle-based materials for drug release is crucial. Innovative chemical, physico- and biochemical approaches for controlled tailor-made degradation or the stimulus-responsive release of substances from these materials, and more, are advantageous. In this review, we discuss current developments, progress, but also pitfalls and setbacks of such approaches in supporting or controlling bone healing. The focus is on the critical evaluation of recent preclinical studies investigating different carrier systems, dual- or co-delivery systems as well as triggered- or targeted delivery systems for release of a panoply of drugs.

The Role of Marine Organic Extract in Bone Regeneration: A Pilot Study

Novel biomaterials capable of accelerating the healing process of skeletal tissues are urgently needed in dentistry. The present in vivo study assessed the osteoconductive and osteoinductive properties of experimental biphasic bioceramics (HA-TCP) modified or not by a nacre extract (marine organic extract, MOE) in a sheep model. Fabrication of MOE involved mixing ground nacre (0.05 g, particle sizes < 0.1 mm) with glacial ethanoic acid (5 mL, pH 7) for 72 hours using external magnetic stirring (25°C). Nonreactive carriers (sterile polythene tubes; 3/animal, radius: 2.5 mm, length: 10.0 mm) pertaining to the control (empty) or experimental groups (HA-TCP or MOE-modified HA-TCP) were implanted intramuscularly into the abdominal segment of the torso in sheep (n = 8, age: 2 years, weight: 45 kg). Euthanization of animals was performed at 3 and 6 months after surgery. Tissues harvested were subjected to macroscopic and radiographic assessments. Specimens were then stained for histological analysis. Both control and experimental animals were capable of inducing the neoformation of fibrous connective tissue at both time points where superior amounts of tissue formation and mineralization were detected for experimental groups (unaltered (at 3 and 6 mos) and MOE-modified HA-TCP (at 3 mos)). Histological results, however, revealed that mature bone formation was only observed for specimens fabricated with MOE-modified HA-TCP in a time-dependent manner. The present study has successfully demonstrated the in vivo utility of experimental biphasic bioceramics modified by MOE in an ectopic grafting sheep model. Promising osteoconductive and osteoinductive properties must be further developed and confirmed by subsequent research.

Scaffold-Based Gene Therapeutics for Osteochondral Tissue Engineering

Significant progress in osteochondral tissue engineering has been made for biomaterials designed to deliver growth factors that promote tissue regeneration. However, due to diffusion characteristics of hydrogels, the accurate delivery of signaling molecules remains a challenge. In comparison to the direct delivery of growth factors, gene therapy can overcome these challenges by allowing the simultaneous delivery of growth factors and transcription factors, thereby enhancing the multifactorial processes of tissue formation. Scaffold-based gene therapy provides a promising approach for tissue engineering through transfecting cells to enhance the sustained expression of the protein of interest or through silencing target genes associated with bone and joint disease. Reports of the efficacy of gene therapy to regenerate bone/cartilage tissue regeneration are widespread, but reviews on osteochondral tissue engineering using scaffold-based gene therapy are sparse. Herein, we review the recent advances in gene therapy with a focus on tissue engineering scaffolds for osteochondral regeneration.

Natural protein bioinspired materials for regeneration of hard tissues

This review describes the protein bioinspired materials for the repair of hard tissues such as enamel, dentin and bone.