Interpenetrating polymer network scaffold of sodium hyaluronate and sodium alginate combined with berberine for osteochondral defect regeneration

Degradable biomedical elastomers: paving the future of tissue repair and regenerative medicine

Degradable biomedical elastomers (DBE), characterized by controlled biodegradability, excellent biocompatibility, tailored elasticity, and favorable network design and processability, have become indispensable in tissue repair. This review critically examines the recent advances of biodegradable elastomers for tissue repair, focusing mainly on degradation mechanisms and evaluation, synthesis and crosslinking methods, microstructure design, processing techniques, and tissue repair applications. The review explores the material composition and cross-linking methods of elastomers used in tissue repair, addressing chemistry-related challenges and structural design considerations. In addition, this review focuses on the processing methods of two- and three-dimensional structures of elastomers, and systematically discusses the contribution of processing methods such as solvent casting, electrostatic spinning, and three-/four-dimensional printing of DBE. Furthermore, we describe recent advances in tissue repair using DBE, and include advances achieved in regenerating different tissues, including nerves, tendons, muscle, cardiac, and bone, highlighting their efficacy and versatility. The review concludes by discussing the current challenges in material selection, biodegradation, bioactivation, and manufacturing in tissue repair, and suggests future research directions. This concise yet comprehensive analysis aims to provide valuable insights and technical guidance for advances in DBE for tissue engineering.

A review of hyaluronic acid-based therapeutics for the treatment and management of arthritis

Hyaluronic acid (HA), a biodegradable, biocompatible and non-immunogenic therapeutic polymer is a key component of the cartilage extracellular matrix (ECM) and has been widely used to manage two major types of arthritis, osteoarthritis (OA) and rheumatoid arthritis (RA). OA joints are characterized by lower concentrations of depolymerized (low molecular weight) HA, resulting in reduced physiological viscoelasticity, while in RA, the associated immune cells are over-expressed with various cell surface receptors such as CD44. Due to HA's inherent viscoelastic property and its ability to target CD44, there has been a surge of interest in developing HA-based systems to deliver various bioactives (drugs and biologics) and manage arthritis. Considering therapeutic benefits of HA in arthritis management and potential advantages of novel delivery systems, bioactive delivery through HA-based systems is beginning to display improved outcomes over bioactive only treatment. The benefits include enhanced bioactive uptake due to receptor-mediated targeting, prolonged retention of bioactives in the synovium, reduced expressions of proinflammatory mediators, enhanced cartilage regeneration, reduced drug toxicity due to sustained release, and improved and cost-effective treatment. This review provides an underlying rationale to prepare and use HA-based bioactive delivery systems for arthritis applications. With special emphasis given to preclinical/clinical results, this article reviews various bioactive-loaded HA-based particulate carriers (organic and inorganic), gels, scaffolds and polymer-drug conjugates that have been reported to treat and manage OA and RA. Furthermore, the review identifies several key challenges and provides valuable suggestions to address them. Various developments, strategies and suggestions described in this review may guide the formulation scientists to optimize HA-based bioactive delivery systems as an effective approach to manage and treat arthritis effectively.

Towards superior biopolymer gels by enabling interpenetrating network structures: A review on types, applications, and gelation strategies

Gels derived from single networks of natural polymers (biopolymers) typically exhibit limited physical properties and thus have seen constrained applications in areas like food and medicine. In contrast, gels founded on a synergy of multiple biopolymers, specifically polysaccharides and proteins, with intricate interpenetrating polymer network (IPN) structures, represent a promising avenue for the creation of novel gel materials with significantly enhanced properties and combined advantages. This review begins with the scrutiny of newly devised IPN gels formed through a medley of polysaccharides and/or proteins, alongside an introduction of their practical applications in the realm of food, medicine, and environmentally friendly solutions. Finally, based on the fact that the IPN gelation process and mechanism are driven by different inducing factors entwined with a diverse amalgamation of polysaccharides and proteins, our survey underscores the potency of physical, chemical, and enzymatic triggers in orchestrating the construction of crosslinked networks within these biomacromolecules. In these mixed systems, each specific inducer aligns with distinct polysaccharides and proteins, culminating in the generation of semi-IPN or fully-IPN gels through the intricate interpenetration between single networks and polymer chains or between two networks, respectively. The resultant IPN gels stand as paragons of excellence, characterized by their homogeneity, dense network structures, superior textural properties (e.g., hardness, elasticity, adhesion, cohesion, and chewability), outstanding water-holding capacity, and heightened thermal stability, along with guaranteed biosafety (e.g., nontoxicity and biocompatibility) and biodegradability. Therefore, a judicious selection of polymer combinations allows for the development of IPN gels with customized functional properties, adept at meeting precise application requirements.

3D printed osteochondral scaffolds: design strategies, present applications and future perspectives

Articular osteochondral (OC) defects are a global clinical problem characterized by loss of full-thickness articular cartilage with underlying calcified cartilage through to the subchondral bone. While current surgical treatments can relieve pain, none of them can completely repair all components of the OC unit and restore its original function. With the rapid development of three-dimensional (3D) printing technology, admirable progress has been made in bone and cartilage reconstruction, providing new strategies for restoring joint function. 3D printing has the advantages of fast speed, high precision, and personalized customization to meet the requirements of irregular geometry, differentiated composition, and multi-layered boundary layer structures of joint OC scaffolds. This review captures the original published researches on the application of 3D printing technology to the repair of entire OC units and provides a comprehensive summary of the recent advances in 3D printed OC scaffolds. We first introduce the gradient structure and biological properties of articular OC tissue. The considerations for the development of 3D printed OC scaffolds are emphatically summarized, including material types, fabrication techniques, structural design and seed cells. Especially from the perspective of material composition and structural design, the classification, characteristics and latest research progress of discrete gradient scaffolds (biphasic, triphasic and multiphasic scaffolds) and continuous gradient scaffolds (gradient material and/or structure, and gradient interface) are summarized. Finally, we also describe the important progress and application prospect of 3D printing technology in OC interface regeneration. 3D printing technology for OC reconstruction should simulate the gradient structure of subchondral bone and cartilage. Therefore, we must not only strengthen the basic research on OC structure, but also continue to explore the role of 3D printing technology in OC tissue engineering. This will enable better structural and functional bionics of OC scaffolds, ultimately improving the repair of OC defects.

In vitro and in vivo efficacy of naturally derived scaffolds for cartilage repair and regeneration

Intrinsically present bioactive cues allow naturally derived materials to mimic important characteristics of cartilage while also facilitating cellular recruitment, infiltration, and differentiation. Such traits are often what tissue engineers desire when they fabricate scaffolds, and yet, literature from the past decade is replete with examples of how most natural constructs with native biomolecules have only offered sub-optimal results in the treatment of cartilage defects. This paper provides an in-depth investigation of the performance of such scaffolds through a review of a collection of natural materials that have been used so far in repairing/regenerating articular cartilage. Although in vivo and clinical studies are the best indicators of scaffold efficacy, it was, however, observed that a large number of natural constructs had very promising scaffold characteristics to begin with, and would often show good in vitro/in vivo results. Finally, an examination of the biochemistry and biomechanics of repair tissues in studies that reported positive outcomes showed that these attributes often approached target cartilage values. The paper concludes with an outline of current trends as well as future directions for the field. STATEMENT OF SIGNIFICANCE: This review offers an exclusive focus on natural scaffold materials for cartilage repair and regeneration and provides a quantitative and qualitative analysis of their performance under a variety of in vitro and in vivo conditions. Readers can learn about environments where natural scaffolds have had the most success and tailor strategies to optimize their own work. Furthermore, given how the glycosaminoglycan (GAG) to hydroxyproline (HYP) ratio and moduli are fundamental attributes of hyaline cartilage, this paper adds to the body of knowledge by exploring how these characteristics reflect in preclinical outcomes. Such perspectives can greatly aid researchers better utilize natural materials for Cartilage Tissue Engineering (CTE).

Sodium alginate-sodium hyaluronate-hydrolyzed silk for microencapsulation and sustained release of kidney tea saponin: The regulation of human intestinal flora in vitro

Kidney tea saponin (KTS) exhibits considerable efficacy in lowering glucose levels; however, it does not have widespread applications owing to its low intestinal utilization. Therefore, in the present study, we prepared sodium alginate (SA)/sodium hyaluronate (HA)/hydrolyzed silk (SF) gel beads for the effective encapsulation and targeted intestinal release of KTS. The gel beads exhibited an encapsulation rate of 90.67 % ± 0.27 % and a loading capacity of 3.11 ± 0.21 mg/mL; furthermore, the release rate of KTS was 95.46 % ± 0.02 % after 8 h of simulated digestion. Fourier transform infrared spectroscopy revealed that the hydroxyl in SA/HA/SF-KTS was shifted toward the strong peak; this was related to KTS encapsulation. Furthermore, scanning electron microscopy revealed that the gel bead space network facilitates KTS encapsulation. In addition, the ability of KTS and the gel beads to inhibit α-amylase (IC50 = 0.93 and 1.37 mg/mL, respectively) and α-glucosidase enzymes (IC50 = 1.17 and 0.93 mg/mL, respectively) was investigated. In vitro colonic fermentation experiments revealed that KTS increased the abundance of Firmicutes/Bacteroidetes and butyric acid-producing bacteria. The study showed that the developed gel-loading system plays a vital role in delivering bioactive substances, achieving slow release, and increasing the abundance and diversity of intestinal flora.

Flavonoid-Loaded Biomaterials in Bone Defect Repair

Skeletons play an important role in the human body, and can form gaps of varying sizes once damaged. Bone defect healing involves a series of complex physiological processes and requires ideal bone defect implants to accelerate bone defect healing. Traditional grafts are often accompanied by issues such as insufficient donors and disease transmission, while some bone defect implants are made of natural and synthetic polymers, which have characteristics such as good porosity, mechanical properties, high drug loading efficiency, biocompatibility and biodegradability. However, their antibacterial, antioxidant, anti-inflammatory and bone repair promoting abilities are limited. Flavonoids are natural compounds with various biological activities, such as antitumor, anti-inflammatory and analgesic. Their good anti-inflammatory, antibacterial and antioxidant activities make them beneficial for the treatment of bone defects. Several researchers have designed different types of flavonoid-loaded polymer implants for bone defects. These implants have good biocompatibility, and they can effectively promote the expression of angiogenesis factors such as VEGF and CD31, promote angiogenesis, regulate signaling pathways such as Wnt, p38, AKT, Erk and increase the levels of osteogenesis-related factors such as Runx-2, OCN, OPN significantly to accelerate the process of bone defect healing. This article reviews the effectiveness and mechanism of biomaterials loaded with flavonoids in the treatment of bone defects. Flavonoid-loaded biomaterials can effectively promote bone defect repair, but we still need to improve the overall performance of flavonoid-loaded bone repair biomaterials to improve the bioavailability of flavonoids and provide more possibilities for bone defect repair.

Evaluation of biocomposite putty with strontium and zinc co-doped 45S5 bioactive glass and sodium hyaluronate

The application of powder or granule formed bioactive glasses in the defect area with the help of a liquid carrier to fill the defects is a subject of interest and is still open to development. In this study, it was aimed to prepare biocomposites of bioactive glasses incorporating different co-dopants with a carrier biopolymer and to create a fluidic material (Sr and Zn co-doped 45S5 bioactive glasses‑sodium hyaluronate). All biocomposite samples were pseudoplastic fluid type, which may be suitable for defect filling and had excellent bioactivity behaviors confirmed by FTIR, SEM-EDS and XRD. Biocomposites with Sr and Zn co-doped bioactive glass had higher bioactivity considering the crystallinity of hydroxyapatite formations compared to biocomposite with undoped bioactive glasses. Biocomposites with high bioactive glass content had hydroxyapatite formations with higher crystallinity compared to biocomposites with low bioactive glass. Furthermore, all biocomposite samples showed non-cytotoxic effect on the L929 cells up to a certain concentration. However, biocomposites with undoped bioactive glass showed cytotoxic effects at lower concentrations compared to biocomposites with co-doped bioactive glass. Thus, biocomposite putties utilizing Sr and Zn co-doped bioactive glasses may be advantageous for orthopedic applications due to their specified rheological, bioactivity, and biocompatibility properties.

From crosslinking strategies to biomedical applications of hyaluronic acid-based hydrogels: A review

Hyaluronic acid (HA) is not only a natural anionic polysaccharide with excellent biocompatibility, biodegradability, and moisturizing effect, but also an essential factor that can affect angiogenesis, inflammation, cell behavior, which has a wide range of applications in the biomedical field. Among them, HA-based hydrogels formed by various physical or chemical crosslinking strategies are particularly striking. They not only retain the physiological function of HA, but also have the skeleton function of hydrogel, which further expands the application of HA. However, HA-based natural hydrogels generally have problems such as insufficient mechanical strength and susceptibility to degradation by hyaluronidase, which limits their application to a certain extent. To solve such problems, researchers have prepared a variety of HA-based multifunctional hydrogels with remarkable properties in recent years by adopting various structural modification methods or novel crosslinking strategies, as well as introducing functionally reactive molecules or moieties, which have extended the application scope. This manuscript systematically introduced common crosslinking strategies of HA-based hydrogels and highlighted the development of novel HA-based hydrogels in anticancer drug delivery, cartilage repair, three-dimensional cell culture, skin dressing and other fields. We hope to provide some references for the subsequent development of HA-based hydrogels in the biomedical field.

Preparation and Characterization of Biomimetic Functional Scaffold with Gradient Structure for Osteochondral Defect Repair

Osteochondral (OC) defects cannot adequately repair themselves due to their sophisticated layered structure and lack of blood supply in cartilage. Although therapeutic interventions are reaching an advanced stage, current clinical therapies to repair defects are in their infancy. Among the possible therapies, OC tissue engineering has shown considerable promise, and multiple approaches utilizing scaffolds, cells, and bioactive factors have been pursued. The most recent trend in OC tissue engineering has been to design gradient scaffolds using different materials and construction strategies (such as bi-layered, multi-layered, and continuous gradient structures) to mimic the physiological and mechanical properties of OC tissues while further enabling OC repair. This review focuses specifically on design and construction strategies for gradient scaffolds and their role in the successful engineering of OC tissues. The current dilemmas in the field of OC defect repair and the efforts of tissue engineering to address these challenges were reviewed. In addition, the advantages and limitations of the typical fabrication techniques for gradient scaffolds were discussed, with examples of recent studies summarizing the future prospects for integrated gradient scaffold construction. This updated and enlightening review could provide insights into our current understanding of gradient scaffolds in OC tissue engineering.

Integrated gradient tissue-engineered osteochondral scaffolds: Challenges, current efforts and future perspectives

The osteochondral defect repair has been most extensively studied due to the rising demand for new therapies to diseases such as osteoarthritis. Tissue engineering has been proposed as a promising strategy to meet the demand of simultaneous regeneration of both cartilage and subchondral bone by constructing integrated gradient tissue-engineered osteochondral scaffold (IGTEOS). This review brought forward the main challenges of establishing a satisfactory IGTEOS from the perspectives of the complexity of physiology and microenvironment of osteochondral tissue, and the limitations of obtaining the desired and required scaffold. Then, we comprehensively discussed and summarized the current tissue-engineered efforts to resolve the above challenges, including architecture strategies, fabrication techniques and in vitro/in vivo evaluation methods of the IGTEOS. Especially, we highlighted the advantages and limitations of various fabrication techniques of IGTEOS, and common cases of IGTEOS application. Finally, based on the above challenges and current research progress, we analyzed in details the future perspectives of tissue-engineered osteochondral construct, so as to achieve the perfect reconstruction of the cartilaginous and osseous layers of osteochondral tissue simultaneously. This comprehensive and instructive review could provide deep insights into our current understanding of IGTEOS.

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Providing main challenges to establish integrated gradient osteochondral scaffold.

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Discussing the current tissue-engineered efforts to resolve the above challenges.

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Highlighting construct techniques, and evaluation index and methods of IGTEOS.

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Discussing the future perspectives to achieve perfect osteochondral reconstruction.

Lithium-Containing Biomaterials Stimulate Cartilage Repair through Bone Marrow Stromal Cells-Derived Exosomal miR-455-3p and Histone H3 Acetylation

The repair of damaged cartilage still remains a great challenge in clinic. It is demonstrated that bone marrow stromal cells (BMSCs)-chondrocytes communication is of great significance for cartilage repair. Moreover, BMSCs have been confirmed to enhance biological function of chondrocytes via exosome-mediated paracrine pathway. Lithium-containing scaffolds have been reported to effectively promote cartilage regeneration; however, whether lithium-containing biomaterial could facilitate cartilage regeneration through regulating BMSCs-derived exosomes has not been illustrated. In the study, the model lithium-substituted bioglass ceramic (Li-BGC) is selected and regulatory effects of BMSCs-derived exosomes after Li-BGC treatment (Li-BGC-Exo) are systemically evaluated. The data reveal that Li-BGC-Exo notably promotes chondrogenesis, which attributes to the upregulated exosomal miR-455-3p transfer, consequently leads to suppression of histone deacetylase 2 (HDAC2) and enhanced histone H3 acetylation in chondrocytes. Notably, BMSCs-derived exosomes after LiCl treatment (LiCl-Exo) exhibits the similar regulatory effect with Li-BGC-Exo, indicating that the pro-chondrogenesis capability of them is mainly owing to the lithium ions. Furthermore, the in vivo study proves that LiCl-Exo remarkably facilitates cartilage regeneration. The research may provide novel possibility for the intrinsic mechanism of chondrogenesis trigged by lithium-containing biomaterials, and suggests that application of lithium-containing scaffolds may be a promising strategy for cartilage regeneration.

An all-silk-derived bilayer hydrogel for osteochondral tissue engineering

Osteochondral repair remains a challenge in clinical practice nowadays despite extensive advances in tissue engineering. The insufficient recruitment of endogenous cells in the early stage and incomplete cell differentiation in the later stage constitute the major difficulty of osteochondral repair. Here, a novel all-silk-derived multifunctional biomaterial platform for osteochondral engineering is reported. The bilayer methacrylated silk fibroin (SilMA) hydrogel was fabricated through stratified photocuring as the basic provisional matrix for tissue regeneration. Platelet-rich plasma (PRP) incorporation promoted the migration and pre-differentiation of the bone marrow mesenchymal stem cells (BMSCs) in the early stage of implantation. The long-term regulation of BMSCs chondrogenesis and osteogenesis was realized by the stratified anchoring of the silk fibroin (SF) microspheres respectively loaded with Kartogenin (KGN) and berberine (BBR) in the hydrogel. The composite hydrogels were further demonstrated to promote BMSCs chondrogenic and osteogenic differentiation under an inflammatory microenvironment and to achieve satisfying cartilage and subchondral bone regeneration with great biocompatibility after 8 weeks of implantation. Since all the components used are readily available and biocompatible and can be efficiently integrated via a simple process, this composite hydrogel scaffold has tremendous potential for clinical use in osteochondral regeneration.

Porous biomaterials for tissue engineering: a review

The field of biomaterials has grown rapidly over the past decades. Within this field, porous biomaterials have played a remarkable role in: (i) enabling the manufacture of complex three-dimensional structures; (ii) recreating mechanical properties close to those of the host tissues; (iii) facilitating interconnected structures for the transport of macromolecules and cells; and (iv) behaving as biocompatible inserts, tailored to either interact or not with the host body. This review outlines a brief history of the development of biomaterials, before discussing current materials proposed for use as porous biomaterials and exploring the state-of-the-art in their manufacture. The wide clinical applications of these materials are extensively discussed, drawing on specific examples of how the porous features of such biomaterials impact their behaviours, as well as the advantages and challenges faced, for each class of the materials.

Knee Osteoarthritis Therapy: Recent Advances in Intra-Articular Drug Delivery Systems

Drug delivery for osteoarthritis (OA) treatment is a continuous challenge because of their poor bioavailability and rapid clearance in joints. Intra-articular (IA) drug delivery is a common strategy and its therapeutic effects depend mainly on the efficacy of the drug-delivery system used for OA therapy. Different types of IA drug-delivery systems, such as microspheres, nanoparticles, and hydrogels, have been rapidly developed over the past decade to improve their therapeutic effects. With the continuous advancement in OA mechanism research, new drugs targeting specific cell/signaling pathways in OA are rapidly evolving and effective drug delivery is critical for treating OA. In this review, recent advances in various IA drug-delivery systems for OA treatment, OA targeted strategies, and related signaling pathways in OA treatment are summarized and analyzed based on current publications.

The chitosan/carboxymethyl cellulose/montmorillonite scaffolds incorporated with epigallocatechin-3-gallate-loaded chitosan microspheres for promoting osteogenesis of human umbilical cord-derived mesenchymal stem cell

Epigallocatechin-3-gallate (EGCG) is a plant-derived flavonoid compound with the ability to promote the differentiation of human bone marrow-derived mesenchymal stem cells (MSCs) into osteoblasts. However, the effect of EGCG on the osteogenic differentiation of the human umbilical cord-derived mesenchymal stem cells (HUMSCs) is rarely studied. Therefore, in this study, the osteogenic effects of EGCG are studied in the HUMSCs by detecting cell proliferation, alkaline phosphatase (ALP) activity, calcium deposition and the expression of relevant osteogenic markers. The results showed that EGCG can promote the proliferation and osteogenic differentiation of the HUMSCs in vitro at a concentration of 2.5-5.0 μM. Unfortunately, the EGCG is easily metabolized by cells during cell culture, which reduces its bioavailability. Therefore, in this paper, EGCG-loaded microspheres (ECM) were prepared and embedded in chitosan/carboxymethyl cellulose/montmorillonite (CS/CMC/MMT) scaffolds to form CS/CMC/MMT-ECM scaffolds for improving the bioavailability of EGCG. The HUMSCs were cultured on CS/CMC/MMT-ECM scaffolds to induce osteogenic differentiation. The results showed that the CS/CMC/MMT-ECM scaffold continuously released EGCG for up to 22 days. In addition, CS/CMC/MMT-ECM scaffolds can promote osteoblast differentiation. Taken together, the present study suggested that entrainment of ECM into CS/CMC/MMT scaffolds was a prospective scheme for promotion osteogenic differentiation of the HUMSCs.

Recent Developments and Current Applications of Hydrogels in Osteoarthritis

Osteoarthritis (OA) is a common degenerative joint disease that causes disability if left untreated. The treatment of OA currently requires a proper delivery system that avoids the loss of therapeutic ingredients. Hydrogels are widely used in tissue engineering as a platform for carrying drugs and stem cells, and the anatomical environment of the limited joint cavity is suitable for hydrogel therapy. This review begins with a brief introduction to OA and hydrogels and illustrates the effects, including the analgesic effects, of hydrogel viscosupplementation on OA. Then, considering recent studies of hydrogels and OA, three main aspects, including drug delivery systems, mesenchymal stem cell entrapment, and cartilage regeneration, are described. Hydrogel delivery improves drug retention in the joint cavity, making it possible to deliver some drugs that are not suitable for traditional injection; hydrogels with characteristics similar to those of the extracellular matrix facilitate cell loading, proliferation, and migration; hydrogels can promote bone regeneration, depending on their own biochemical properties or on loaded proregenerative factors. These applications are interlinked and are often researched together.

3D Printing for Bone-Cartilage Interface Regeneration

Due to the vasculature defects and/or the avascular nature of cartilage, as well as the complex gradients for bone-cartilage interface regeneration and the layered zonal architecture, self-repair of cartilage and subchondral bone is challenging. Currently, the primary osteochondral defect treatment strategies, including artificial joint replacement and autologous and allogeneic bone graft, are limited by their ability to simply repair, rather than induce regeneration of tissues. Meanwhile, over the past two decades, three-dimension (3D) printing technology has achieved admirable advancements in bone and cartilage reconstruction, providing a new strategy for restoring joint function. The advantages of 3D printing hybrid materials include rapid and accurate molding, as well as personalized therapy. However, certain challenges also exist. For instance, 3D printing technology for osteochondral reconstruction must simulate the histological structure of cartilage and subchondral bone, thus, it is necessary to determine the optimal bioink concentrations to maintain mechanical strength and cell viability, while also identifying biomaterials with dual bioactivities capable of simultaneously regenerating cartilage. The study showed that the regeneration of bone-cartilage interface is crucial for the repair of osteochondral defect. In this review, we focus on the significant progress and application of 3D printing technology for bone-cartilage interface regeneration, while also expounding the potential prospects for 3D printing technology and highlighting some of the most significant challenges currently facing this field.

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.

A review of the berberine natural polysaccharide nanostructures as potential anticancer and antibacterial agents

Despite the promising medicinal properties, berberine (BBR), due to its relatively poor solubility in plasma, low bio-stability and limited bioavailability is not used broadly in clinical stages. Due to these drawbacks, drug delivery systems (DDSs) based on nanoscale natural polysaccharides, are applied to address these concerns. Natural polymers are biodegradable, non-immunogenic, biocompatible, and non-toxic agents that are capable of trapping large amounts of hydrophobic compounds in relatively small volumes. The use of nanoscale natural polysaccharide improves the stability and pharmacokinetics of the small molecules and, consequently, increases the therapeutic effects and reduces the side effects of the small molecules. Therefore, this paper presents an overview of the different methods used for increasing the BBR solubility and bioavailability. Afterwards, the pharmacodynamic and pharmacokinetic of BBR nanostructures were discussed followed by the introduction of natural polysaccharides of plant (cyclodextrines, glucomannan), the shells of crustaceans (chitosan), and the cell wall of brown marine algae (alginate)-based origins used to improve the dissolution rate of poorly soluble BBR and their anticancer and antibacterial properties. Finally, the anticancer and antibacterial mechanisms of free BBR and BBR nanostructures were surveyed. In conclusion, this review may pave the way for providing some useful data in the development of BBR-based platforms for clinical applications.

Reticulocalbin 1 is required for proliferation and migration of non-small cell lung cancer cells regulated by osteoblast-conditioned medium

Reticulocalbin1 (RCN1) is implicated in tumorigenesis and tumour progression. However, whether RCN1‐mediated bone metastasis of non‐small cell lung cancer (NSCLC) cells was elusive. Here, we assessed the effect of osteoblast‐conditioned medium (CM) on proliferation and migration of NSCLC cell line, NCI‐H1299 and NCI‐H460 cells, and identified the soluble mediators in CMs from osteoblasts and NSCLC cells using MTT, Clonogenicity, Transwell, wound healing, RT‐PCR, and Western blotting assays, and LC‐MS/MS analysis, respectively. Furthermore, the role of RCN1 was investigated in NSCLC cells cultured with or without osteoblast‐CM. Tumour growth and bone resorption were measured in a nude mouse model bearing NCI‐H1299 cells transduced with shRNA/RCN1 vector using in vivo imaging technique and micro‐CT. The results showed that RCN1 with a higher abundance in osteoblast‐CM, which was present in extracellular vesicles (EVs), enhanced RCN1 expression in NSCLC cells. Osteoblast‐CM partially offset the inhibitory effect of RCN1 depletion on proliferation and migration of NSCLC cells. RCN1 depletion‐induced endoplasmic reticulum (ER) stress caused by increasing GRP78, CHOP, IRE1α, p‐IRE1α, p‐PERK and p‐JNK, which was positively regulated by self‐induced autophagy, contributed to suppression of proliferation and migration in NCI‐H1299 cells. Therefore, osteoblasts produced RCN1 to transfer into NSCLC cells partially through EVs, facilitating proliferation and migration of NSCLC cells via blocking ER stress. RCN1 could be required for proliferation and migration of NSCLC cells regulated by osteoblast‐CM.

Berberine for bone regeneration: Therapeutic potential and molecular mechanisms

ETHNOPHARMACOLOGICAL RELEVANCE

Berberine is a quaternary ammonium isoquinoline alkaloid, mainly extracted from plants berberaceae, papaveraceae, ranunculaceae and rutaceae such as coptis chinensis Franch, Phellodendron chinense, and berberis pruinosa. The plants are extensively used in traditional medicine for treating infection, diabetes, arrhythmia, tumor, osteoporosis et al. Pharmacological studies showed berberine has effects of anti-inflammation, anti-tumor, lower blood lipid, lower blood glucose, anti-osteoporosis, anti-osteoarthritis et al. AIM OF THE STUDY: This review aims to summarize the application of natural herbs that contain berberine, the further use and development of berberine, the effects as well as mechanism of berberine on osteoblasts and osteoclasts, the recent advances of in vivo studies, in order to provide a scientific basis for its traditional uses and to prospect of the potential applications of berberine in clinics.

METHOD

The research was achieved by retrieving from the online electronic database, including PubMed, Web of Science, Google Scholar and China national knowledge infrastructure (CNKI). Patents, doctoral dissertations and master dissertations are also searched.

RESULTS

Berberine has a long history of medicinal use to treat various diseases including bone disease in China. Recent studies have defined its function in promoting bone regeneration and great potential in developing new drugs. But the systemic mechanism of berberine on bone regeneration still needs more research to clarify.

CONCLUSION

This review has systematically summarized the application, pharmacological effects, mechanism as well as in vivo studies of berberine and herbs which contain berberine. Berberine has a definite effect in promoting the proliferation and differentiation of osteoblasts as well as inhibiting the production of osteoclasts to promote bone regeneration. However, the present studies about the system mechanisms and pharmacological activity of berberine were incomplete. Applying berberine for new drug development remains an exciting and promising alternative to bone regeneration engineering, with broad potential for therapeutic and clinical practice.

Osteochondral Tissue Engineering: The Potential of Electrospinning and Additive Manufacturing

The socioeconomic impact of osteochondral (OC) damage has been increasing steadily over time in the global population, and the promise of tissue engineering in generating biomimetic tissues replicating the physiological OC environment and architecture has been falling short of its projected potential. The most recent advances in OC tissue engineering are summarised in this work, with a focus on electrospun and 3D printed biomaterials combined with stem cells and biochemical stimuli, to identify what is causing this pitfall between the bench and the patients' bedside. Even though significant progress has been achieved in electrospinning, 3D-(bio)printing, and induced pluripotent stem cell (iPSC) technologies, it is still challenging to artificially emulate the OC interface and achieve complete regeneration of bone and cartilage tissues. Their intricate architecture and the need for tight spatiotemporal control of cellular and biochemical cues hinder the attainment of long-term functional integration of tissue-engineered constructs. Moreover, this complexity and the high variability in experimental conditions used in different studies undermine the scalability and reproducibility of prospective regenerative medicine solutions. It is clear that further development of standardised, integrative, and economically viable methods regarding scaffold production, cell selection, and additional biochemical and biomechanical stimulation is likely to be the key to accelerate the clinical translation and fill the gap in OC treatment.

The development of natural polymer scaffold-based therapeutics for osteochondral repair

Due to the limited regenerative capacity of cartilage, untreated joint defects can advance to more extensive degenerative conditions such as osteoarthritis. While some biomaterial-based tissue-engineered scaffolds have shown promise in treating such defects, no scaffold has been widely accepted by clinicians to date. Multi-layered natural polymer scaffolds that mimic native osteochondral tissue and facilitate the regeneration of both articular cartilage (AC) and subchondral bone (SCB) in spatially distinct regions have recently entered clinical use, while the transient localized delivery of growth factors and even therapeutic genes has also been proposed to better regulate and promote new tissue formation. Furthermore, new manufacturing methods such as 3D bioprinting have made it possible to precisely tailor scaffold micro-architectures and/or to control the spatial deposition of cells in requisite layers of an implant. In this way, natural and synthetic polymers can be combined to yield bioactive, yet mechanically robust, cell-laden scaffolds suitable for the osteochondral environment. This mini-review discusses recent advances in scaffolds for osteochondral repair, with particular focus on the role of natural polymers in providing regenerative templates for treatment of both AC and SCB in articular joint defects.

Berberine carried gelatin/sodium alginate hydrogels with antibacterial and EDTA-induced detachment performances

Most existing hydrogel wound dressings lack gentle detachment property. In this work, novel hydrogels with anti-bacterial and induced detachment properties were prepared. Both gelatin (G) and sodium alginate (SA) are natural polymer materials. The G/SA hydrogels were prepared by dual cross-linking. The addition of SA significantly improves the mechanical properties of composite hydrogels. The tensile modulus and elongation at break of the G/SA hydrogels with 2.0% SA could reach 99.23 ± 2.18 kPa and 85.47 ± 5.01%, respectively. In addition, the interconnected porous network and high swelling ratio (over 9.99 ± 0.33) are beneficial to the transmission of oxygen and absorption of exudates to accelerate the healing of wound. Subsequently, berberine (BBR) was loaded into the G/SA hydrogels. The BBR/G/SA hydrogels show sustained drug release for 168 h and exhibit anti-bacterial effect against Staphylococcus aureus. The results of L929 cells cultured with the hydrogel extracts indicate good biocompatibility. Finally, results of EDTA-induced detachment performances demonstrate that the hydrogels could be removed from the wound as the internal structure destroyed. All illustrated results above demonstrated the BBR carried G/SA hydrogels have potential used as wound dressing materials in future.

Berberine-releasing electrospun scaffold induces osteogenic differentiation of DPSCs and accelerates bone repair

The repair of skeletal defects in maxillofacial region remains an intractable problem, the rising technology of bone tissue engineering provides a new strategy to solve it. Scaffolds, a crucial element of tissue engineering, must have favorable biocompatibility as well as osteoinductivity. In this study, we prepared berberine/polycaprolactone/collagen (BBR/PCL/COL) scaffolds with different concentrations of berberine (BBR) (25, 50, 75 and 100 μg/mL) through electrospinning. The influence of dosage on scaffold morphology, cell behavior and in vivo bone defect repair were systematically studied. The results indicated that scaffolds could release BBR stably for up to 27 days. Experiments in vitro showed that BBR/PCL/COL scaffolds had appropriate biocompatibility in the concentration of 25-75 μg/mL, and 50 and 75 μg/mL scaffolds could significantly promote osteogenic differentiation of dental pulp stem cells. Scaffold with 50 μg/mL BBR was implanted into the critical bone defect of rats to evaluate the ability of bone repair in vivo. It was found that BBR/PCL/COL scaffold performed more favorable than polycaprolactone/collagen (PCL/COL) scaffold. Overall, our study is the first to evaluate the capability of in vivo bone repair of BBR/PCL/COL electrospun scaffold. The results indicate that BBR/PCL/COL scaffold has prospective potential for tissue engineering applications in bone regeneration therapy.

Evaluation of Glycerylphytate Crosslinked Semi- and Interpenetrated Polymer Membranes of Hyaluronic Acid and Chitosan for Tissue Engineering

In the present study, semi- and interpenetrated polymer network (IPN) systems based on hyaluronic acid (HA) and chitosan using ionic crosslinking of chitosan with a bioactive crosslinker, glycerylphytate (G1Phy), and UV irradiation of methacrylate were developed, characterized and evaluated as potential supports for tissue engineering. Semi- and IPN systems showed significant differences between them regarding composition, morphology, and mechanical properties after physicochemical characterization. Dual crosslinking process of IPN systems enhanced HA retention and mechanical properties, providing also flatter and denser surfaces in comparison to semi-IPN membranes. The biological performance was evaluated on primary human mesenchymal stem cells (hMSCs) and the systems revealed no cytotoxic effect. The excellent biocompatibility of the systems was demonstrated by large spreading areas of hMSCs on hydrogel membrane surfaces. Cell proliferation increased over time for all the systems, being significantly enhanced in the semi-IPN, which suggested that these polymeric membranes could be proposed as an effective promoter system of tissue repair. In this sense, the developed crosslinked biomimetic and biodegradable membranes can provide a stable and amenable environment for hMSCs support and growth with potential applications in the biomedical field.

Suppressing PLCγ1 enhances osteogenic and chondrogenic potential of BMSCs

Phosphatidylcholine-specific phospholipase Cγ1 (PLCγ1) is involved in regulating cell metabolism. However, little is known how PLCγ1 directs BMSC differentiation. Here, we investigated the role of PLCγ1 in rat BMSC differentiation into osteoblasts and chondrocytes. The results of Alizarin red and Alcian blue staining showed that PLCγ1 inhibitor U73122 significantly enhanced the mineralization capacity and proteoglycan deposition of BMSCs. The results of qPCR technique and Western blot analysis showed that long-term treatment of U73122 enhanced COL1A1 and OPG mRNA levels and Collagen 1A1, BMP2, and p-Smad1/5/9 protein levels and that short-term treatment of U73122 enhanced COL2A1 and SOX9 mRNA levels and Collagen 2, SOX9, Aggrecan, TGF-β3, and p-Smad2/3 protein levels. Decreased p-mTOR and p-P38 contributed to enhanced osteogenic potentials of BMSCs and increased p-P38 contributed to enhanced chondrogenic potentials of BMSCs. The scaffold transplantation with U73122+BMSC was more efficacious than BMSC alone for osteochondral defect repair in a rat model. Therefore, suppressing PLCγ1 could improve the capacity to effectively use BMSCs for cell therapy of osteochondral defect.

High-Performance Cyanate Ester Resins with Interpenetration Networks for 3D Printing

As the 3D printing technology is getting more and more popular and useful, demands for materials for 3D printing have increased significantly. Cyanate ester (CE) resin possesses the characteristics of high heat distortion temperature and high glass transition temperature, outstanding mechanical properties, low dielectric constant, and excellent water uptake. However, CE resin has not been widely used in 3D printing of UV curing because it is difficult for photopolymerizable groups to graft onto the chains of CE resin. On the other hand, the glass transition temperature (T_g) of the homopolymer of the tris(2-hydroxyethyl)isocyanurate triacrylate (THEICTA) outclasses that of other acrylates. Although THEICTA is particularly advantageous to prepare a UV-curing prepolymer with high glass transition temperature, it also cannot be directly used for fabricating heat-resistant 3D-printed parts because it is solid and adding diluents will reduce the thermal stability of printed objects. This study is unique in producing 3D-printed materials, in which the THEICTA tactfully dissolves in low viscosity (about 100 mPa·s under 25 °C) bisphenol E cyanate (BECy) without sacrificing two kinds of bulk material properties. In the process of 3D printing, the carbon-carbon double bonds from THEICTA are cured by radical polymerization. Postprinting thermal treatment transforms three cyanate groups to a triazine ring structure. Additionally, the two kinds of structures are interpenetrating. The high-performance 3D-printing material has potential in fields ranging from space flight and aviation to the automotive and electronic industry.

[The role of Wnt signaling pathway in osteoarthritis via the dual-targeted regulation of cartilage and subchondral bone]

Objective

To summarize the active changes of Wnt signaling pathway in osteoarthritis (OA) as well as the influence and mechanism of dual-targeted regulation on cartilage and subchondral bone and the role of crosstalk between them on OA process.

Methods

The relevant literature concerning the articular cartilage, subchondral bone, and crosstalk between them in OA and non-OA states by Wnt signaling pathway in vivo and vitro experimental studies and clinical studies in recent years was reviewed, and the mechanism was analyzed and summarized.

Results

Wnt signaling can regulate the differentiation and function of chondrocytes and osteoblasts through the classic β-catenin-dependent or non-classical β-catenin-independent Wnt signaling pathway and its cross-linking with other signaling pathways, thereby affecting the cartilage and bone metabolism. Moreover, Wnt signaling pathway can activate the downstream protein Wnt1-inducible-signaling pathway protein 1 to regulate the progress of OA and it also can be established gap junctions between different cells in cartilage and subchondral bone to communicate molecules directly to regulate OA occurrence and development. Intra-articular injection of Wnt signaling inhibitor SM04690 can inhibit the progress of OA, and overexpression of Wnt signaling pathway inhibitor Dickkopf in osteoblasts can antagonize the role of vascular endothelial growth factor work on chondrocytes and inhibit the catabolism of its matrix.

Conclusion

The regulation of metabolism and function of cartilage and subchondral bone and crosstalk between them is through interactions among Wnt signaling pathway and molecules of other signaling. Therefore, it plays an vital role in the occurrence and development of OA and is expected to become a new target of OA treatment through intervention and regulation of Wnt signaling pathway.

Ice-templating of chitosan/agarose porous composite hydrogel with adjustable water-sensitive shape memory property and multi-staged degradation performance

Water-induced shape memory polymers (SMPs) may have important applications in the fields of tissue engineering and biomedicine. However, most of the ideal candidates often suffer from non-biodegradation, weak mechanical strength and random macro-porous structure, which do limit the creativity and dynamism of water-sensitive SPMs. To address above issue, in this study, by incorporating the pH-responsive chitosan (CHIT) into a thermoplastic elastomer agarose (Agar) matrix and ice-templating, a novel dual-responsive interpenetrating polymer network hydrogel with highly porous structure was facilely prepared, which has a ultra-high porosity (>95 %) and water-induced shape recovery ratio (>90 %, response time <1 min). Results showed that such shape memory property is erasable and pH-dependent which achieves a great shape memory property at high pH and then can be erased in acidic condition. In vitro dissolution test indicates the great possibility of programming the multi-staged degradation of such composites in response to sequential pH or thermal stimuli. Based on the porous internal structure, we also demonstrate some potential applications of the hydrogels for assembly of nanomaterials, such as Au nanorods for remote sensing system and model protein of insulin for drug controlled release. Moreover, the process proved to be versatile, allowing the use of most natural polymer including gelatin, alginate, and so on. Thus, coupling of such straightforward fabrication approach, multifunctionality and biodegradable prerequisite feature indicates great potential for use in the minimally invasive surgery.

Advances of injectable hydrogel-based scaffolds for cartilage regeneration

Articular cartilage is an important load-bearing tissue distributed on the surface of diarthrodial joints. Due to its avascular, aneural and non-lymphatic features, cartilage has limited self-regenerative properties. To date, the utilization of biomaterials to aid in cartilage regeneration, especially through the use of injectable scaffolds, has attracted considerable attention. Various materials, therapeutics and fabrication approaches have emerged with a focus on manipulating the cartilage microenvironment to induce the formation of cartilaginous structures that have similar properties to the native tissues. In particular, the design and fabrication of injectable hydrogel-based scaffolds have advanced in recent years with the aim of enhancing its therapeutic efficacy and improving its ease of administration. This review summarizes recent progress in these efforts, including the structural improvement of scaffolds, network cross-linking techniques and strategies for controlled release, which present new opportunities for the development of injectable scaffolds for cartilage regeneration.

A Col I and BCP ceramic bi-layer scaffold implant promotes regeneration in osteochondral defects

Osteochondral defects occur in the superficial cartilage region, intermediate calcified cartilage, and subchondral bone. Due to the limited regenerative capacity and complex zonal structure, it is critically difficult to develop strategies for osteochondral defect repair that could meet clinical requirements. In this study, type I collagen (Col I) and BCP ceramics were used to fabricate a new bi-layer scaffold for regeneration in osteochondral defects. The in vitro studies showed that the bi-layer scaffold provided special functions for cell migration, proliferation and secretion due to the layered scaffold structure. The in vivo results demonstrated that the bi-layered scaffold could effectively promote the regeneration of both the cartilage and the subchondral bone, and the newly formed cartilage layer, with a similar structure and thickness to the natural cartilaginous layer, could seamlessly integrate with the surrounding natural cartilage and regenerate an interface layer to mimic the native osteochondral structure.

A new bi-layer scaffold composed of Col I and BCP ceramic was prepared to regenerate osteochondral defect. The result demonstrated the bi-layer scaffold could effectively promote the regeneration of both the cartilage and the subchondral bone layer.