Construction of Wogonin Nanoparticle-Containing Strontium-Doped Nanoporous Structure on Titanium Surface to Promote Osteoporosis Fracture Repair

From hard tissues to beyond: Progress and challenges of strontium-containing biomaterials in regenerative medicine applications

Tissue engineering and regenerative medicine have emerged as crucial disciplines focused on the development of new tissues and organs to overcome the limitations of traditional treatments for tissue damage caused by accidents, diseases, or aging. Strontium ion (Sr2+) has garnered significant attention for its multifaceted role in promoting regeneration medicine and therapy, especially in bone tissue regeneration. Recently, numerous studies further confirm that Sr2+ also plays a critical in soft tissue regeneration. This review firstly summarizes the influence of Sr2+ on critical biological processes such as osteogenesis, angiogenesis, immune modulation, matrix synthesis, mineralization, and antioxidative defence mechanisms. Then details the classification, properties, advantages, and limitations of Sr-containing biomaterials (SrBMs). Additionally, this review extends to the current applications of SrBMs in regenerative medicine for diverse tissues, including bone, cartilage, skeletal muscle, dental pulp, cardiac tissue, skin, hair follicles, etc. Moreover, the review addresses the challenges associated with current SrBMs and provides insights for their future designing and applications in regenerative medicine.

Finely controlled bioceramic granules and sonoporation for osteogenic bone defect repair and reconstruction

Osteoporotic fractures caused by imbalance in bone homeostasis like chemotherapy, loss of ovarian function，glucocorticoid use and aging require special surgical procedure to treat and restore anatomical function. However, due to escalating bone weakness and impairment, it remains a clinical challenge to treat these types of fracture defects through conventional means. Herein, we fabricated a novel calcium silicate‑strontium (CS-Sr35) bioceramic granules with high biological properties and combined it with ultrasound aided sonoporation (sono) in augmenting osteoporotic critical-sized bone defect. The use of sonoporation mediated by microbubble was to influence efficient response for tissue permeability and delivery of bioactive ions from the bioceramic scaffold. The graded robust granule with adjustable microstructure exhibited physiochemical and biointegration properties favorable for ion release in vitro and osteogenic related activities in vivo. Herein, we compared the treatment of bone defect repair using (i) no scaffold (ii) CS-Sr35 only and (iii) CS-Sr35 + sono. The gradual bone repair process was elucidated by X-ray, histology and micro-CT analyses. Overall, our results showed that the CS-Sr35 + sono exhibited a tailored biodissolution behavior with complete defect repair and reconstruction. Meanwhile, the group with only CS-Sr35 granules had less osteoblastic healing while the blank group showed inadequate critical-sized defect repair throughout the study. Our study suggests that, the synergistic technique of combining bioceramic granule with sonoporation significantly optimizes osteogenic activity and biomineralization ability of the bioceramic granule for new bone growth in osteoporotic pathology and also this tailored technique provides versatile approach for improving the biological effect for next generation reconstruction and repair of diseased bone defect.

Microwave-Sintered Nano-SiC Reinforced 8SiC/Ti-3Cu Composite: Fabrication, Wear Resistance, Antibacterial Function, and Biocompatibility

The significance of biomedical applications of Ti alloys is best emphasized by their widespread utilization as implantable materials, such as internal supports and bone replacements. Ti alloys are sensitive to fretting wear, which leads to the early failure of Ti implants. Improved wear resistance of such implants is essential to ensure a prolonged implant life. Based on the structure-function-integrated concept, this work unprecedentedly designs and fabricates an antibacterial 8SiC/Ti-3Cu composite with improved wear resistance using microwave sintering from pure Ti, Cu, and nano-SiC powders. For comparison, SiC-free Ti-3Cu composite is manufactured under the same conditions using microwave sintering. The addition of 8 vol.% SiC to Ti-3Cu significantly reduces the porosity and pore size of composites. The 8SiC/Ti-3Cu shows a Vickers hardness of 353 HV, compressive strength of 803 MPa, elastic modulus of 28.7 GPa, and a significantly increased wear resistance (wear rate decreased by 70% compared to Ti-3Cu). In addition, 8SiC/Ti-3Cu exhibits excellent electrochemical corrosion resistance, biocompatibility in relation to MC3T3-E1 cells, and a bacteriostatic rate over 99% against E. coli. The combination of the wear-resistant nano-reinforced SiC and antibacterial Ti2Cu in the 8SiC/Ti-3Cu composite renders it a highly promising implant material.

Metal-Protein Hybrid Materials: Unlocking New Frontiers in Biomedical Applications

Metal-protein hybrid materials represent a novel class of functional materials that exhibit exceptional physicochemical properties and tunable structures, rendering them remarkable applications in diverse fields, including materials engineering, biocatalysis, biosensing, and biomedicine. The design and development of multifunctional and biocompatible metal-protein hybrid materials have been the subject of extensive research and a key aspiration for practical applications in clinical settings. This review provides a comprehensive analysis of the design strategies, intrinsic properties, and biomedical applications of these hybrid materials, with a specific emphasis on their potential in cancer therapy, drug and vaccine delivery, antibacterial treatments, and tissue regeneration. Through rational design, stable metal-protein hybrid materials can be synthesized using straightforward methods, enabling them with therapeutic, delivery, immunomodulatory, and other desired functionalities. Finally, the review outlines the existing limitations and challenges associated with metal-protein hybrid materials and evaluates their potential for clinical translation, providing insights into their practical implementation within biomedical applications.

Multiscale Hierarchical Micro- and Nano-Surface Induced by High-Repetition-Rate Femtosecond Laser Promote Peri-Implant Osseointegration

Micro- and nanomorphological modification and roughening of titanium implant surfaces can enhance osseointegration; however, the optimal morphology remains unclear. Laser processing of implant surfaces has demonstrated significant potential due to its precision, controllability, and environmental friendliness. Femtosecond lasers, through precise optimization of processing parameters, can modify the surface of any solid material to generate micro- and nanomorphologies of varying scales and roughness. Inspired by the multiscale micro- and nanostructures of natural bone tissue, this study employed a high-repetition-rate femtosecond laser to fabricate three distinct micro- and nanomorphologies on titanium implant surfaces, characterized by low (LTi), medium (MTi), and high (HTi) roughness, exhibiting multiscale coexistence. Comprehensive characterization of the modified surfaces included analysis of morphology, roughness, wettability, and elemental composition. Furthermore, in vitro and in vivo experiments were conducted to evaluate osteogenic differentiation and osseointegration capabilities. Results revealed that the HTi surface, exhibiting high roughness, presents a multiscale hierarchical micro- and nanostructure composed of micrometer-sized spheres, submicrometer-sized corrugations, and nanometer-sized particles. In vitro studies demonstrated that the HTi surface promoted earlier adhesion, spreading, and enhanced osteogenic differentiation of osteoblasts, while in vivo studies indicated improved bone formation and osseointegration. In conclusion, multiscale hierarchical micro- and nanosurfaces with high roughness generated by high-repetition-rate femtosecond laser processing hold considerable promise for titanium implant applications.

Compliant immune response of silk-based biomaterials broadens application in wound treatment

The unique properties of sericin and silk fibroin (SF) favor their widespread application in biopharmaceuticals, particularly in wound treatment and bone repair. The immune response directly influences wound healing cycle, and the extensive immunomodulatory functions of silk-based nanoparticles and hydrogels have attracted wide attention. However, different silk-processing methods may trigger intense immune system resistance after implantation into the body. In this review, we elaborate on the inflammation and immune responses caused by the implantation of sericin and SF and also explore their anti-inflammatory properties and immune regulatory functions. More importantly, we describe the latest research progress in enhancing the immunotherapeutic and anti-inflammatory effects of composite materials prepared from silk from a mechanistic perspective. This review will provide a useful reference for using the correct processes to exploit silk-based biomaterials in different wound treatments.

Moxibustion Alleviates Inflammation via SIRT5-mediated Post-translational Modification and Macrophage Polarization

Macrophage polarisation is influenced by Sirtuin5 (SIRT5), which is crucial for regulating anti-inflammatory processes. Moxibustion, a traditional Chinese medicine therapy, exerts anti-inflammatory effects by altering the succinate/α-ketoglutarate (α-KG) ratio, an indicator of the M1 to M2 macrophage shift. Glutamate dehydrogenase 1 (GLUD1), a key enzyme involved in α-KG production, is desuccinylated by SIRT5. Currently, the potential influence of moxibustion on SIRT5-GLUD1-α-KG-mediated macrophage polarization in inflammatory diseases remains unexplored. C57BL/6 J and Sirt5 knockout mice were used as complete Freund's adjuvant (CFA)-induced adjuvant arthritis models. Moxibustion and acupoint injections of MC3482 were administered. Paw capacity asssays and ELISA were performed to quantify inflammatory effects and the expression of succinate, and α-KG expressions. Flow cytometry (FCM) and immunofluorescence were used to assesss the expression of M1- and M2-like macrophages. LC-MS/MS-based proteomic analysis was performed, and GLUD1 was identified desuccinylated protein associated with SIRT5. Western blotting and immunoprecipitation (IP) were used to detect SIRT5, GLUD1, and succinylated GLUD1expressions. Moxibustion and the SIRT5-mediated desuccinylation inhibitor MC3482 decreased inflammation by increasing the number of M2 macrophages and reducing the number of M1 macrophage in the CFA model. The potential mechanism may be related to the effects of moxibustion and SIRT5 inhibition, which inverted succinate and α-KG levels in the CFA group, resulting in low succinate, high α-KG, and increased GLUD1 succinylation after treatment. These findings suggest that the anti-inflammatory effects moxibustion are related to the impact of macrophage conversion after SIRT5-mediated post-translational modification.

Synergistic Enhancement of Antibacterial and Osteo-Immunomodulatory Activities of Titanium Implants via Dual-Responsive Multifunctional Surfaces

Bone implant-associated infections and inflammations, primarily caused by bacteria colonization, frequently result in unsuccessful procedures and pose significant health risks to patients. To mitigate these challenges, the development of engineered implants with spatiotemporal regulation capabilities, designed to inhibit bacterial survival and modulate immune responses in the early stage, while promoting bone defect healing in the late stage is proposed. The implants are functionalized with ε-poly-l-lysine-phenylboronic acid (PP) via dynamic boronic ester bonds, which facilitate its release through a reactive oxygen species (ROS) and pH-responsive strategy, thereby establishing an antibacterial microenvironment on and around the implants. Additionally, the dynamic metal coordination interaction facilitates the loading and sustained release of Sr2+ under an acidic environment, providing immunomodulatory and osteogenic effects. The ROS/pH-responsive feature, coupled with the implant-bone tissue integration process, affords precise spatiotemporal regulation of the Ti-TA-Sr-PP implants. This strategy represents a promising approach for the preparation of advanced bone implants.

Strontium-Alix interaction enhances exosomal miRNA selectively loading in synovial MSCs for temporomandibular joint osteoarthritis treatment

The ambiguity of etiology makes temporomandibular joint osteoarthritis (TMJOA) "difficult-to-treat". Emerging evidence underscores the therapeutic promise of exosomes in osteoarthritis management. Nonetheless, challenges such as low yields and insignificant efficacy of current exosome therapies necessitate significant advances. Addressing lower strontium (Sr) levels in arthritic synovial microenvironment, we studied the effect of Sr element on exosomes and miRNA selectively loading in synovial mesenchymal stem cells (SMSCs). Here, we developed an optimized system that boosts the yield of SMSC-derived exosomes (SMSC-EXOs) and improves their miRNA profiles with an elevated proportion of beneficial miRNAs, while reducing harmful ones by pretreating SMSCs with Sr. Compared to untreated SMSC-EXOs, Sr-pretreated SMSC-derived exosomes (Sr-SMSC-EXOs) demonstrated superior therapeutic efficacy by mitigating chondrocyte ferroptosis and reducing osteoclast-mediated joint pain in TMJOA. Our results illustrate Alix's crucial role in Sr-triggered miRNA loading, identifying miR-143-3p as a key anti-TMJOA exosomal component. Interestingly, this system is specifically oriented towards synovium-derived stem cells. The insight into trace element-driven, site-specific miRNA selectively loading in SMSC-EXOs proposes a promising therapeutic enhancement strategy for TMJOA.

Influence of hyaluronic acid and chitosan molecular weight on the adhesion of circulating tumor cell on multilayer films

CD44 is a cell receptor glycoprotein overexpressed in circulating tumor cells (CTCs), with levels linked to an increase in metastatic capacity of several tumors. Hyaluronic acid (HA), the natural ligand of CD44, has primarily been investigated for tumor cell interaction in self-assembled polyelectrolyte multilayer films, with little attention given to the complementary polycation. In this study, we screened sixteen different polyelectrolyte multilayer assemblies of HA and chitosan (CHI) to identify key assembly parameters and surface properties that control and govern CTCs adhesion. Statistics analysis revealed a major role of CHI molecular weight in the adhesion, followed by its combinatorial response either with HA ionization degree or ionic strength. PM-IRRAS analysis demonstrated a correlation between the orientation of HA carboxyl groups on the film surface and CTCs adhesion, directly impacted by CHI molecular weight. Overall, although CTCs binding onto the surface of multilayer films is primarily driven by HA-CD44 interaction, both chitosan properties and film assembly conditions modulate this interaction. These findings illustrate an alternative to modifying the performance of biomaterials with minimal changes in the composition of multilayer films.

Biomimetic Scaffolds Regulating the Iron Homeostasis for Remolding Infected Osteogenic Microenvironment

The treatment of infected bone defects (IBDs) needs simultaneous elimination of infection and acceleration of bone regeneration. One mechanism that hinders the regeneration of IBDs is the iron competition between pathogens and host cells, leading to an iron deficient microenvironment that impairs the innate immune responses. In this work, an in situ modification strategy is proposed for printing iron-active multifunctional scaffolds with iron homeostasis regulation ability for treating IBDs. As a proof-of-concept, ultralong hydroxyapatite (HA) nanowires are modified through in situ growth of a layer of iron gallate (FeGA) followed by incorporation in the poly(lactic-co-glycolic acid) (PLGA) matrix to print biomimetic PLGA based composite scaffolds containing FeGA modified HA nanowires (FeGA-HA@PLGA). The photothermal effect of FeGA endows the scaffolds with excellent antibacterial activity. The released iron ions from the FeGA-HA@PLGA help restore the iron homeostasis microenvironment, thereby promoting anti-inflammatory, angiogenesis and osteogenic differentiation. The transcriptomic analysis shows that FeGA-HA@PLGA scaffolds exert anti-inflammatory and pro-osteogenic differentiation by activating NF-κB, MAPK and PI3K-AKT signaling pathways. Animal experiments confirm the excellent bone repair performance of FeGA-HA@PLGA scaffolds for IBDs, suggesting the promising prospect of iron homeostasis regulation therapy in future clinical applications.

Application of advanced surface modification techniques in titanium-based implants: latest strategies for enhanced antibacterial properties and osseointegration

Titanium-based implants, renowned for their excellent mechanical properties, corrosion resistance, and biocompatibility, have found widespread application as premier implant materials in the medical field. However, as bioinert materials, they often face challenges such as implant failure caused by bacterial infections and inadequate osseointegration post-implantation. Thus, to address these issues, researchers have developed various surface modification techniques to enhance the surface properties and bioactivity of titanium-based implants. This review aims to outline several key surface modification methods for titanium-based implants, including acid etching, sol-gel method, chemical vapor deposition, electrochemical techniques, layer-by-layer self-assembly, and chemical grafting. It briefly summarizes the advantages, limitations, and potential applications of these technologies, presenting readers with a comprehensive perspective on the latest advances and trends in the surface modification of titanium-based implants.

Recent development and applications of electrodeposition biocoatings on medical titanium for bone repair

Bioactive coatings play a crucial role in enhancing the osseointegration of titanium implants for bone repair. Electrodeposition offers a versatile and efficient technique to deposit uniform coatings onto titanium surfaces, endowing implants with antibacterial properties, controlled drug release, enhanced osteoblast adhesion, and even smart responsiveness. This review summarizes the recent advancements in bioactive coatings for titanium implants used in bone repair, focusing on various electrodeposition strategies based on material-structure synergy. Firstly, it outlines different titanium implant materials and bioactive coating materials suitable for bone repair. Then, it introduces various electrodeposition methods, including electrophoretic deposition, anodization, micro-arc oxidation, electrochemical etching, electrochemical polymerization, and electrochemical deposition, discussing their applications in antibacterial, osteogenic, drug delivery, and smart responsiveness. Finally, it discusses the challenges encountered in the electrodeposition of coatings for titanium implants in bone repair and potential solutions.

Intelligent Supramolecular Modification for Implants: Endogenous Regulation of Bone Defect Repair in Osteoporosis

Addressing osteoporosis-related bone defects, a supramolecular strategy is innovated for modifying carbon fiber reinforced polyether ether ketone (CF/PEEK) composites. By covalently attaching intelligent macromolecules via in situ RAFT polymerization, leveraging the unique pathological microenvironment in patients with iron-overloaded osteoporosis, intelligent supramolecular modified implant surface possesses multiple endogenous modulation capabilities. After implantation, surface brush-like macromolecules initially resist macrophage adhesion, thereby reducing the level of immune inflammation. Over time, the molecular chains undergo conformational changes due to Fe (III) mediated supramolecular self-assembly, transforming into mechanistic signals. These signals are then specifically transmitted to pre-osteoblast cell through the binding capacity of the KRSR short peptide at the molecular terminus, induced their osteogenic differentiation via the YAP/β-catenin signaling axis. Furthermore, osteoblasts secrete alkaline phosphatase (ALP), which significantly hydrolyzes phosphate ester bonds in surface macromolecular side groups, resulting in the release of alendronate (ALN). This process further improves the local osteoporotic microenvironment. This intelligent surface modification tailors bone repair to individual conditions, automatically realize multiple endogenous regulation once implanted, and truly realize spontaneous activation of a series of responses conducive to bone repair in vivo. It is evidenced by improved bone regeneration in iron-overloaded osteoporotic rabbits and supported by in vitro validations.

The Effect of Antibacterial-Osteogenic Surface Modification on the Osseointegration of Titanium Implants: A Static and Dynamic Strategy

Titanium (Ti) and its alloys are widely used biomaterials in bone repair. Although these biomaterials possess stable properties and good biocompatibility, the high elastic modulus and low surface activity of Ti implants have often been associated with infection, inflammation, and poor osteogenesis. Therefore, there is an urgent need to modify the surface of Ti implants, where changes in surface morphology or coatings loading can confer specific functions to help them adapt to the osseointegration formation phase and resist bacterial infection. This can further ensure a healthy microenvironment for bone regeneration as well as the promotion of immunomodulation, angiogenesis, and osteogenesis. Therefore, in this review, we evaluated various functional Ti implants after surface modification, both in terms of static modifications and dynamic response strategies, mainly focusing on the synergistic effects of antimicrobial activities and functionalized osteogenic. Finally, the current challenges and future perspectives are summarized to provide innovative and effective solutions for osseointegration and bone defect repair.

Multifunctional Prosthesis Surface: Modification of Titanium with Cinnamaldehyde-Loaded Hierarchical Titanium Dioxide Nanotubes

Orthopedic prostheses are the ultimate therapeutic solution for various end-stage orthopedic conditions. However, aseptic loosening and pyogenic infections remain as primary complications associated with these devices. In this study, a hierarchical titanium dioxide (TiO2) nanotube drug delivery system loaded with cinnamaldehyde for the surface modification of titanium implants, is constructed. These specially designed dual-layer TiO2 nanotubes enhance material reactivity and provide an extensive drug-loading platform within a short time. The introduction of cinnamaldehyde enhances the bone integration performance of the scaffold (simultaneously promoting bone formation and inhibiting bone resorption), anti-inflammatory capacity, and antibacterial properties. In vitro experiments have demonstrated that this system promoted osteogenesis by upregulating both Wnt/β-catenin and MAPK signaling pathways. Furthermore, it inhibits osteoclast formation, suppresses macrophage-mediated inflammatory responses, and impedes the proliferation of Staphylococcus aureus and Escherichia coli. In vivo experiments shows that this material enhances bone integration in a rat model of femoral defects. In addition, it effectively enhances the antibacterial and anti-inflammatory properties in a subcutaneous implant in a rat model. This study provides a straightforward and highly effective surface modification strategy for orthopedic Ti implants.

Construction of Magnesium Phosphate Chemical Conversion Coatings with Different Microstructures on Titanium to Enhance Osteogenesis and Angiogenesis

Titanium (Ti) and its alloys are widely used as hard tissue substitutes in dentistry and orthopedics, but their low bioactivity leads to undesirable osseointegration defects in the early osteogenic phase. Surface modification is an important approach to overcome these problems. In the present study, novel magnesium phosphate (MgP) coatings with controllable structures were fabricated on the surface of Ti using the phosphate chemical conversion (PCC) method. The effects of the microstructure on the physicochemical and biological properties of the coatings on Ti were researched. The results indicated that accelerators in PCC solution were important factors affecting the microstructure and properties of the MgP coatings. In addition, the coated Ti exhibited excellent hydrophilicity, high bonding strength, and good corrosion resistance. Moreover, the biological results showed that the MgP coatings could improve the spread, proliferation, and osteogenic differentiation of mouse osteoblast cells (MC3T3-E1) and vascular differentiation of human umbilical vein endothelial cells (HUVECs), indicating that the coated Ti samples had a great effect on promoting osteogenesis and angiogenesis. Overall, this study provided a new research idea for the surface modification of conventional Ti to enhance osteogenesis and angiogenesis in different bone types for potential biomedical applications.

Immunomodulatory nanomedicine for osteoporosis: Current practices and emerging prospects

Osteoporosis results from the disruption of the balance between bone resorption and bone formation. However, classical anti-osteoporosis drugs exhibit several limitations in clinical applications, such as multiple adverse reactions and poor therapeutic effects. Therefore, there is an urgent need for alternative treatment strategies. With the evolution of immunomodulatory nanomedicine, a variety of nanomaterials have been designed for anti-osteoporosis treatment, offering prospects of minimal adverse reactions, enhanced bone induction, and high osteogenic activity. This review initially provides a brief overview of the fundamental principles of bone reconstruction, current osteogenic clinical methods in osteoporosis treatment, and the significance of osteogenic-angiogenic coupling, laying the groundwork for understanding the pathophysiology and therapeutics of osteoporosis. Subsequently, the article emphasizes the relationship between bone immunity and osteogenesis-angiogenesis coupling and provides a detailed analysis of the application of immunomodulatory nanomedicines in the treatment of osteoporosis, including various types of nanomaterials and their integration with carrier biomaterials. Importantly, we discuss the potential of some emerging strategies in immunomodulatory nanomedicine for osteoporosis treatment. This review introduces the innovative applications of immunomodulatory nanomedicine in the treatment of osteoporosis, aiming to serve as a reference for the application of immunomodulatory nanomedicine strategies in osteoporosis treatment. STATEMENT OF SIGNIFICANCE: Osteoporosis, as one of the most prevalent skeletal disorders, poses a significant threat to public health. To date, conventional anti-osteoporosis strategies have been limited in efficacy and plagued with numerous side effects. Fortunately, with the advancement of research in osteoimmunology and nanomedicine, strategies integrating these two fields show great promise in combating osteoporosis. Nanomedicine with immunomodulatory properties exhibits enhanced efficiency, prolonged effectiveness, and increased safety. However, as of now, there exists no comprehensive review amalgamating immunomodulation with nanomedicine to delineate the progress of immunomodulatory nanomedicine in osteoporosis treatment, as well as the future direction of this strategy.

Enhancing immune modulation and bone regeneration on titanium implants by alleviating the hypoxic microenvironment and releasing bioactive ions

Bone implantation inevitably causes damage to surrounding vasculature, resulting in a hypoxic microenvironment that hinders bone regeneration. Although titanium (Ti)-based devices are widely used as bone implants, their inherent bioinert surface leads to poor osteointegration. Herein, a strontium peroxide (SrO2)-decorated Ti implant, Ti_P@SrO2, was constructed through coating with poly-L-lactic acid (PLLA) to alleviate the hypoxic microenvironment and transform the bioinert surface of the implant into a bioactive surface. PLLA degradation resulted in an acidic microenvironment and the release of SrO2 nanoparticles. The acidic microenvironment then accelerated the decomposition of SrO2, resulting in the release of O2 and Sr ions. O2 released from Ti_P@SrO2 can alleviate the hypoxic microenvironment, thus enhancing cell proliferation in an O2-insufficient microenvironment. Furthermore, under hypoxic and normal microenvironments, Ti_P@SrO2 enhanced alkaline phosphatase activity and bone-related gene expression in C3H10T1/2 cells with the continuous release of Sr ions. Meanwhile, Ti_P@SrO2 suppressed M1 polarization and promoted M2 polarization of bone marrow-derived monocytes under hypoxic and normal conditions. Furthermore, in a rat implantation model, the implant enhanced new bone formation and improved osteointegration after modification with SrO2. In summary, the newly designed O2- and Sr ion-releasing Ti implants are promising for applications in bone defects.

Metal mixture and osteoporosis risk: Insights from plasma metabolite profiling

The pathophysiology of osteoporosis (OP) is influenced by exposure to nonessential harmful metals and insufficient or excessive intake of necessary metals. Investigating multiple plasma metals, metabolites, and OP risk among older adults may reveal novel clues of underlying mechanisms for metal toxicity on bone mass. A total of 294 adults ≥ 55 years from Wuhan communities were included. Plasma concentrations of 23 metals and metabolites were measured via inductively coupled plasma-mass spectrometry and global metabolite detection. To investigate the relationships between plasma metals, OP risk, and OP-related metabolites, three different statistical techniques were used: generalized linear regression model, two-way orthogonal partial least-squares analysis (O2PLS), and weighted quantile sum (WQS). The mean ages were 66.82 and 66.21 years in OP (n = 115) and non-OP (n = 179) groups, respectively. Of all 2999 metabolites detected, 111 differential between-group members were observed. The OP risk decreased by 58.5% (OR=0.415, 95% CI: 0.237, 0.727) per quartile increment in the WQS index indicative of metal mixture exposure. Consistency remained for bone mineral density (BMD) measurements. The O2PLS model identified the top five OP-related metabolites, namely, DG(18:2_22:6), 3-phenoxybenzoic acid, TG(16:1_16:1_22:6), TG(16:0_16:0_20:4), and TG(14:1_18:2_18:3), contributing most to the joint covariation between the metal mixture and metabolites. Significant correlations between each of them and the metal mixture were found using WQS regression. Furthermore, the five metabolites mediated the associations of the metal mixtures, BMD, and OP risk. Our findings shed additional light on the mediation functions of plasma metabolites in the connection between multiple metal co-exposure and OP pathogenesis and offer new insights into the probable mechanisms underpinning the bone effects of the metal mixture.

Progress in Surface Modification of Titanium Implants by Hydrogel Coatings

Although titanium and titanium alloys have become the preferred materials for various medical implants, surface modification technology still needs to be strengthened in order to adapt to the complex physiological environment of the human body. Compared with physical or chemical modification methods, biochemical modification, such as the introduction of functional hydrogel coating on implants, can fix biomolecules such as proteins, peptides, growth factors, polysaccharides, or nucleotides on the surface of the implants, so that they can directly participate in biological processes; regulate cell adhesion, proliferation, migration, and differentiation; and improve the biological activity on the surface of the implants. This review begins with a look at common substrate materials for hydrogel coatings on implant surfaces, including natural polymers such as collagen, gelatin, chitosan, and alginate, and synthetic materials such as polyvinyl alcohol, polyacrylamide, polyethylene glycol, and polyacrylic acid. Then, the common construction methods of hydrogel coating (electrochemical method, sol-gel method and layer-by-layer self-assembly method) are introduced. Finally, five aspects of the enhancement effect of hydrogel coating on the surface bioactivity of titanium and titanium alloy implants are described: osseointegration, angiogenesis, macrophage polarization, antibacterial effects, and drug delivery. In this paper, we also summarize the latest research progress and point out the future research direction. After searching, no previous relevant literature reporting this information was found.

Recent Advance of Strontium Functionalized in Biomaterials for Bone Regeneration

Bone defect disease causes damage to people’s lives and property, and how to effectively promote bone regeneration is still a big clinical challenge. Most of the current repair methods focus on filling the defects, which has a poor effect on bone regeneration. Therefore, how to effectively promote bone regeneration while repairing the defects at the same time has become a challenge for clinicians and researchers. Strontium (Sr) is a trace element required by the human body, which mainly exists in human bones. Due to its unique dual properties of promoting the proliferation and differentiation of osteoblasts and inhibiting osteoclast activity, it has attracted extensive research on bone defect repair in recent years. With the deep development of research, the mechanisms of Sr in the process of bone regeneration in the human body have been clarified, and the effects of Sr on osteoblasts, osteoclasts, mesenchymal stem cells (MSCs), and the inflammatory microenvironment in the process of bone regeneration have been widely recognized. Based on the development of technology such as bioengineering, it is possible that Sr can be better loaded onto biomaterials. Even though the clinical application of Sr is currently limited and relevant clinical research still needs to be developed, Sr-composited bone tissue engineering biomaterials have achieved satisfactory results in vitro and in vivo studies. The Sr compound together with biomaterials to promote bone regeneration will be a development direction in the future. This review will present a brief overview of the relevant mechanisms of Sr in the process of bone regeneration and the related latest studies of Sr combined with biomaterials. The aim of this paper is to highlight the potential prospects of Sr functionalized in biomaterials.

Wogonin induces ferroptosis in pancreatic cancer cells by inhibiting the Nrf2/GPX4 axis

Pancreatic cancer is a common gastrointestinal tract malignancy. Currently, the therapeutic strategies for pancreatic cancers include surgery, radiotherapy, and chemotherapy; however, the surgical procedure is invasive, and the overall curative outcomes are poor. Furthermore, pancreatic cancers are usually asymptomatic during early stages and have a high degree of malignancy, along with a high rate of recurrence and metastasis, thereby increasing the risk of mortality. Studies have shown that ferroptosis regulates cell proliferation and tumour growth and reduces drug resistance. Hence, ferroptosis could play a role in preventing and treating cancers. Wogonin is a flavonoid with anticancer activity against various cancers, including pancreatic cancer. It is extracted from the root of Scutellaria baicalensis Georgi. In this study, we show that wogonin inhibits the survival and proliferation of human pancreatic cancer cell lines and induces cell death. We performed RNA-sequencing and analysed the differentially expressed gene and potential molecular mechanism to determine if wogonin reduced cell survival via ferroptosis. Our results showed that wogonin upregulates the levels of Fe²⁺, lipid peroxidation and superoxide and decreases the protein expression levels of ferroptosis suppressor genes, and downregulates level of glutathione in pancreatic cancer cells. In addition, ferroptosis inhibitors rescue the ferroptosis-related events induced by wogonin, thereby confirming the role of ferroptosis. A significant increase in ferroptosis-related events was observed after treatment with both wogonin and ferroptosis inducer. These results show that wogonin could significantly reduces pancreatic cancer cell proliferation and induce ferroptosis via the Nrf2/GPX4 axis. Therefore, wogonin could be potentially used for treating patients with pancreatic cancer.