Bisphosphonate-based hydrogel mediates biomimetic negative feedback regulation of osteoclastic activity to promote bone regeneration

Immune regulation enhances osteogenesis and angiogenesis using an injectable thiolated hyaluronic acid hydrogel with lithium-doped nano-hydroxyapatite (Li-nHA) delivery for osteonecrosis

Osteonecrosis is a devastating orthopedic disease in clinic that generally occurs in the femoral head associating with corticosteroid use up to 49 % in patients. In particular, glucocorticoids induced osteonecrosis of the femoral head is closely related to the local immune response that characterized by abnormal macrophage activation and inflammatory cell infiltration at the necrotic site, forming a pro-inflammatory microenvironment dominated by M1 macrophages, and thus leads to failure of bone repair and regeneration. Here, we report a bone regeneration strategy that constructs an immune regulatory biomaterial platform using an injectable thiolated hyaluronic acid hydrogel with lithium-doped nano-hydroxyapatite (Li-nHA@Gel) delivery for osteonecrosis treatment. Li-nHA@Gel achieved a sustain and longterm release of Li ions, which might enhance M2 macrophage polarization through the activation of the JAK1/STAT6/STAT3 signaling pathway, and the following induced pro-repair immune microenvironment mediated the enhancement of the osteogenic and angiogenic differentiation. Moreover, both in vitro and in vivo studies indicated that Li-nHA@Gel enhanced M2 macrophage polarization, osteogenesis, and angiogenesis, and thus promoted the bone and blood vessel formation. Taken together, this novel bone immunomodulatory biomaterial platform that promotes bone regeneration by enhancing M2 macrophage polarization, osteogenesis, and angiogenesis could be a promising strategy for osteonecrosis treatment.

Injectable Self-Healing Oxidized Starch/Gelatin Hybrid Hydrogel for Preventing Aseptic Loosening of Bone Tissue Engineering

Aseptic loosening presents a formidable challenge within the realm of bone tissue engineering, playing a pivotal role in the occurrence of joint replacement failures. The development of therapeutic materials characterized by an optimal combination of mechanical properties and biocompatibility is imperative to ensure the enduring functionality of bone implants over extended periods. In this context, this study introduced an injectable, temperature-sensitive irisin/oxidized starch/gelatin hybrid hydrogel (I-OG) system. The hierarchical cross-linked structure endows the I-OG hydrogel with controlled and adjustable physical and chemical properties, making it easy to adapt to different clinical environments. This hydrogel exhibits satisfactory injectable properties, excellent biocompatibility, and good temperature sensitivity. The sol-gel point of the I-OG hydrogel, close to the body temperature, allows it to cushion the shaking of the implant and maintain an intact state during compression of bone tissue. Significantly, the I-OG hydrogel effectively filled the gap between the implant and bone tissue, successfully inhibiting aseptic loosening induced by titanium particles, a result that confirmed the slow release of the irisin protein from the gel. Collectively, the findings from this study strongly support the proposition that functional hydrogels, typified by the I-OG system, hold substantial promise as an accessible and efficient treatment strategy for mitigating aseptic loosening.

[Bone/cartilage immunomodulating hydrogels: construction strategies and applications]

Objective

To review the research progress in the construction strategy and application of bone/cartilage immunomodulating hydrogels.

Methods

The literature related to bone/cartilage immunomodulating hydrogels at home and abroad in recent years was reviewed and summarized from the immune response mechanism of different immune cells, the construction strategy of immunomodulating hydrogels, and their practical applications.

Results

According to the immune response mechanism of different immune cells, the biological materials with immunoregulatory effect is designed, which can regulate the immune response of the body and thus promote the regeneration of bone/cartilage tissue. Immunomodulating hydrogels have good biocompatibility, adjustability, and multifunctionality. By regulating the physical and chemical properties of hydrogel and loading factors or cells, the immune system of the body can be purposively regulated, thus forming an immune microenvironment conducive to osteochondral regeneration.

Conclusion

Immunomodulating hydrogels can promote osteochondral repair by affecting the immunomodulation process of host organs or cells. It has shown a wide application prospect in the repair of osteochondral defects. However, more data support from basic and clinical experiments is needed for this material to further advance its clinical translation process.

Recent advances in immunomodulatory hydrogels biomaterials for bone tissue regeneration

There is a high incidence of fractures in clinical practice and therapy. The repairment of critical size defects in the skeletal system remains a huge challenge for surgeons and researchers, which can be overcame by the application of bone tissue-engineered biomaterials. An increasing number of investigations have revealed that the immune system plays a vital role in the repair of bone defects, especially macrophages, which can modulate the integration of biomaterials and bone regeneration in multiple ways. Therefore, it has become increasingly important in regenerative medicine to regulate macrophage polarization to prevent inflammation caused by biomaterial implantation. Recent studies have stressed the importance of hydrogel-based modifications and the incorporation of various cellular and molecular signals for regulating immune responses to promote bone tissue regeneration and integrate biomaterials. In this review, we first elaborate briefly on the described the general physiological mechanism and process of bone tissue regeneration. Then, we summarized the immunomodulatory role macrophages play in bone repair. In addition, the role of hydrogel-based immune modification targeting macrophage modulation in accelerating and enhancing bone tissue regeneration was also discussed. Finally, we highlighted future directions and research strategies related to hydrogel optimization for the regulation of the immune response during bone regeneration and healing.

Seamlessly Adhesive Bionic Periosteum Patches Via Filling Microcracks for Defective Bone Healing

Current artificial designs of the periosteum focus on osteogenic or angiogenic properties, while ignoring the filling and integration with bone microcracks, which trigger a prolonged excessive inflammatory reaction and lead to failure of bone regeneration. In this study, seamless adhesive biomimetic periosteum patches (HABP/Sr-PLA) were prepared to fill microcracks in defective bone via interfacial self-assembly induced by Sr ions mediated metal-ligand interactions among pamidronate disodium-modified hyaluronic acid (HAPD), black phosphorus (BP), and hydrophilic polylactic acid (PLA). In vitro, HABP/Sr-PLA exhibited excellent self-healing properties, seamlessly filled bone microcracks, and significantly enhanced osteogenesis and angiogenesis. Furthermore, in a rat cranial defect model, HABP/Sr-PLA was demonstrated to significantly promote the formation of blood vessels and new bone under mild 808 nm photothermal stimulation (42.8 °C), and the highest protein expression of CD31 and OPN was five times higher than that of the control group and other groups. Therefore, the proposed seamless microcrack-filled bionic periosteum patch is a promising clinical strategy for promoting bone repair.

Microinjection Molded Biopolymeric Airway Stent with Antibacterial and Anti-Hyperplastic Properties

Central airway stenosis is a condition that the diameter of the trachea or main bronchus shrinkage is caused by external compression or internal tissue hyperplasia, which can cause difficulty breathing, asphyxia, and even death. Airway stenting is an easy way to restore the patency of the central airway, but airway stents commonly used in clinical practice can lead to complications such as mucus plugging, bacterial infection, and granulation tissue hyperplasia. Moreover, the non-degradable characteristic makes it requires a second operation to remove, which has the potential to cause tissue damage. In this study, a biodegradable airway stent is fabricated by microinjection molding using the bioelastomer of poly (L-lactide-co-ε-caprolactone) as the matrix material. The airway stent has excellent mechanical properties and an appropriate degradation rate. The hydrophilic surface of the airway stent can inhibit mucus plugging. The loading of silver nanoparticles and cisplatin endows the stent with antibacterial and anti-hyperplastic functions. In vitro and in vivo experiments demonstrate that this study provides an antibacterial and anti-hyperplastic biodegradable airway stent with elastic properties to avoid secondary removal operation and reduce complications associated with mucus plugging, bacterial infection, and granulation tissue hyperplasia.

3D Biomimetic Calcified Cartilaginous Callus that Induces Type H Vessels Formation and Osteoclastogenesis

The formation of a calcified cartilaginous callus (CACC) is crucial during bone repair. CACC can stimulate the invasion of type H vessels into the callus to couple angiogenesis and osteogenesis, induce osteoclastogenesis to resorb the calcified matrix, and promote osteoclast secretion of factors to enhance osteogenesis, ultimately achieving the replacement of cartilage with bone. In this study, a porous polycaprolactone/hydroxyapatite-iminodiacetic acid-deferoxamine (PCL/HA-SF-DFO) 3D biomimetic CACC is developed using 3D printing. The porous structure can mimic the pores formed by the matrix metalloproteinase degradation of the cartilaginous matrix, HA-containing PCL can mimic the calcified cartilaginous matrix, and SF anchors DFO onto HA for the slow release of DFO. The in vitro results show that the scaffold significantly enhances angiogenesis, promotes osteoclastogenesis and resorption by osteoclasts, and enhances the osteogenic differentiation of bone marrow stromal stem cells by promoting collagen triple helix repeat-containing 1 expression by osteoclasts. The in vivo results show that the scaffold significantly promotes type H vessels formation and the expression of coupling factors to promote osteogenesis, ultimately enhancing the regeneration of large-segment bone defects in rats and preventing dislodging of the internal fixation screw. In conclusion, the scaffold inspired by biological bone repair processes effectively promotes bone regeneration.

Lyophilized Platelet-Rich Fibrin Exudate-Loaded Carboxymethyl Chitosan/GelMA Hydrogel for Efficient Bone Defect Repair

Platelet-rich fibrin (PRF) is an autologous growth factor carrier that promotes bone tissue regeneration, but its effectiveness is restrained by poor storage capabilities, uncontrollable concentration of growth factors, unstable shape, etc. Herein, we developed a photocrosslinkable composite hydrogel by incorporating lyophilized PRF exudate (LPRFe) into the carboxymethyl chitosan methacryloyl (CMCSMA)/gelatin methacryloyl (GelMA) hydrogel to effectively solve the dilemma of PRF. The hydrogel possessed suitable physical properties and sustainable release ability of growth factors in LPRFe. The LPRFe-loaded hydrogel could improve the adhesion, proliferation, migration, and osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs). Furthermore, the animal experiments demonstrated that the hydrogel possessed excellent biocompatibility and biodegradability, and the introduction of LPRFe in the hydrogel can effectively accelerate the bone healing process. Conclusively, the combination of LPRFe with CMCSMA/GelMA hydrogel may be a promising therapeutic approach for bone defects.

Targeting Endogenous Reactive Oxygen Species Removal and Regulating Regenerative Microenvironment at Annulus Fibrosus Defects Promote Tissue Repair

The excessive reactive oxygen species (ROS) level, inflammation, and weak tissue regeneration ability after annulus fibrosus (AF) injury constitute an unfavorable microenvironment for AF repair. AF integrity is crucial for preventing disc herniation after discectomy; however, there is no effective way to repair the AF. Herein, a composite hydrogel integrating properties of antioxidant, anti-inflammation, and recruitment of AF cells is developed through adding mesoporous silica nanoparticles modified by ceria and transforming growth factor β3 (TGF-β3) to the hydrogels. The nanoparticle loaded gelatin methacrylate/hyaluronic acid methacrylate composite hydrogels eliminate ROS and induce anti-inflammatory M2 type macrophage polarization. The released TGF-β3 not only plays a role in recruiting AF cells but is also responsible for promoting extracellular matrix secretion. The composite hydrogels can be solidified in situ in the defect area to effectively repair AF in rats. The strategies targeting endogenous ROS removal and improving the regenerative microenvironment by the nanoparticle-loaded composite hydrogels have potential applications in AF repair and intervertebral disc herniation prevention.

Antisenescence ZIF-8/Resveratrol Nanoformulation with Potential for Enhancement of Bone Fracture Healing in the Elderly

Accumulation of senescent cells in the elderly impairs bone homeostasis. It is important to alleviate cell senescence and scavenge excessive oxidative stress for enhanced bone fracture healing in elderly patients. In this study, resveratrol (RSV), an antioxidant drug, was encapsulated in a biocompatible zeolitic imidazolate framework-8 (ZIF-8) nanoparticle to protect it from oxidation and improve its bioavailability. Cells responsible for bone healing, including osteoblasts, bone marrow-derived mesenchymal stem cells (BMSCs), macrophages, and endothelial cells, were used to evaluate the regulatory role of the nanoformulation in the alleviation of cellular senescence and promotion of cell functions. It was proved that the nanoformulation sustainably released RSV with well-preserved bioactivity and improved bioavailability. Cell experiments confirmed that ZIF-8/RSV was capable of alleviating the senescence of cells [human osteoblasts (HOBs), BMSCs, H₂O₂-induced senescent vascular endothelial cells (HUVECs)] and scavenging excessive intracellular reactive oxygen species (ROS). Excitingly, the ZIF-8/RSV improved the osteogenic ability of senescent osteoblasts and promoted macrophage M2 polarization. In addition, the ZIF-8/RSV also enhanced the angiogenic function of senescent HUVECs. More importantly, the ZIF-8/RSV nanoformulation outperformed the REV alone, indicating the critical role of encapsulation using ZIF-8. These findings suggest that the ZIF-8/RSV nanoformulation exhibits potential for bone fracture treatment in elderly patients.

Smart Orthopedic Biomaterials and Implants

Musculoskeletal injuries including bone defects continue to present a significant challenge in orthopedic surgery due to suboptimal healing. Bone reconstruction strategies focused on the use of biological grafts and bone graft substitutes in the form of biomaterials-based 3D structures in fracture repair. Recent advances in biomaterials science and engineering have resulted in the creation of intricate 3D bone-mimicking structures that are mechanically stable, biodegradable, and bioactive to support bone regeneration. Current efforts are focused on improving the biomaterial and implant physicochemical properties to promote interactions with the host tissue and osteogenesis. The "smart" biomaterials and their 3D structures are designed to actively interact with stem/progenitor cells and the extracellular matrix (ECM) to influence the local environment towards osteogenesis and de novo tissue formation. This article will summarize such smart biomaterials and the methodologies to apply either internal or external stimuli to control the tissue healing microenvironment. A particular emphasis is also made on the use of smart biomaterials and strategies to create functional bioactive implants for bone defect repair and regeneration.

Phosphine chalcogenides and their derivatives from red phosphorus and functionalized pyridines, imidazoles, pyrazoles and their antimicrobial and cytostatic activity

Tertiary phosphine oxides, phosphine sulfides, and phosphine selenides containing pyridine, imidazole, and pyrazole groups have been synthesized via the reaction of elemental phosphorus or secondary phosphine oxides with functional pyridines, imidazoles, and pyrazoles. Alkyl tris(2-pyridylethyl)phosphonium iodide and bromide are also obtained by quaternization of the corresponding phosphine. Antimicrobial activity of the synthesized compounds, including nitrogen-containing heterocycles, phosphorus, selenium, and sulfur, with respect to Enterococcus durans, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa microorganisms is evaluated. It is found that phosphine chalcogenides bearing imidazole (14, 19), pyrazole (13), and pyridine fragments (5, 9) and phosphonium salts (11, 12) can be considered as new promising antibacterial agents. For some synthesized compounds, LC₅₀ is determined. Phosphine oxide with methylpyrazole fragments (13) and phosphonium salts (11, 12) show strong profile of antimicrobial activity, and cytotoxic effect of phosphonium bromide having a long chain radical (12) is by order of magnitude higher than that of cisplatin. We believe that the results obtained may contribute to the development of highly effective agents for the treatment and prevention of bacterial infections and cancers.

Advances in materials-based therapeutic strategies against osteoporosis

Osteoporosis is caused by the disruption in homeostasis between bone formation and bone resorption. Conventional management of osteoporosis involves systematic drug administration and hormonal therapy. These treatment strategies have limited curative efficacy and multiple adverse effects. Biomaterials-based therapeutic strategies have recently emerged as promising alternatives for the treatment of osteoporosis. The present review summarizes the current status of biomaterials designed for managing osteoporosis. The advantages of biomaterials-based strategies over conventional systematic drug treatment are presented. Different anti-osteoporotic delivery systems are concisely addressed. These materials include injectable hydrogels and nanoparticles, as well as anti-osteoporotic bone tissue engineering materials. Fabrication techniques such as 3D printing, electrostatic spinning and artificial intelligence are appraised in the context of how the use of these adjunctive techniques may improve treatment efficacy. The limitations of existing biomaterials are critically analyzed, together with deliberation of the future directions in biomaterials-based therapies. The latter include discussion on the use of combination strategies to enhance therapeutic efficacy in the osteoporosis niche.

Baicalin Nanocomplexes with an In Situ-Forming Biomimetic Gel Implant for Repair of Calvarial Bone Defects via Localized Sclerostin Inhibition

In situ-forming hydrogels are highly effective in covering complex and irregular tissue defects. Herein, a biomimetic gel implant (CS-GEL) consisting of methacrylated chondroitin sulfate and gelatin is obtained via visible light irradiation, which displays rapid gelation (∼30 s), suitable mechanical properties, and biological features to support osteoblast attachment and proliferation. Sclerostin is proven to be a viable target to promote osteogenesis. Hence, baicalin, a natural flavonoid with a high affinity to sclerostin, is selected as the therapeutic compound to achieve localized neutralization of sclerostin. To overcome its poor solubility and permeability, a baicalin nanocomplex (BNP) is synthesized using Solutol HS15, which is then dispersed in the CS-GEL to afford a nanocomposite delivery system, i.e., BNP-loaded gel (BNP@CS-GEL). In vitro, BNP significantly downregulated the level of sclerostin in MLO-Y4 osteocytes. In vivo, either CS-GEL or BNP@CS-GEL is proven to effectively promote osteogenesis and angiogenesis in a calvarial critical-sized bone defect rat model, with BNP@CS-GEL showing the best pro-healing effect. Specifically, the BNP@CS-GEL-treated group significantly downregulated the sclerostin level as compared to the sham group (p < 0.05). RANKL expression was also significantly suppressed by BNP in MLO-Y4 cells and BNP@CS-GEL in vivo. Collectively, our study offers a facile and viable gel platform in combination with nanoparticulated baicalin for the localized neutralization of sclerostin to promote bone regeneration and repair.

Reduction of Osteoclastic Differentiation of Raw 264.7 Cells by EMF Exposure through TRPV4 and p-CREB Pathway

In this study, we investigated the effect of EMF exposure on the regulation of RANKL-induced osteoclast differentiation in Raw 264.7 cells. In the EMF-exposed group, the cell volume did not increase despite RANKL treatment, and the expression levels of Caspase-3 remained much lower than those in the RANKL-treated group. TRAP and F-actin staining revealed smaller actin rings in cells exposed to EMF during RANKL-induced differentiation, indicating that EMF inhibited osteoclast differentiation. EMF-irradiated cells exhibited reduced mRNA levels of osteoclastic differentiation markers cathepsin K (CTSK), tartrate-resistant acid phosphatase (TRAP), and matrix metalloproteinase 9 (MMP-9). Furthermore, as measured by RT-qPCR and Western blot, EMF induced no changes in the levels of p-ERK and p-38; however, it reduced the levels of TRPV4 and p-CREB. Overall, our findings indicate that EMF irradiation inhibits osteoclast differentiation through the TRPV4 and p-CREB pathway.

Rational Design of Soft-Hard Interfaces through Bioinspired Engineering

Soft-hard tissue interfaces in nature present a diversity of hierarchical transitions in composition and structure to address the challenge of stress concentrations that would otherwise arise at their interface. The translation of these into engineered materials holds promise for improved function of biomedical interfaces. Here, soft-hard tissue interfaces found in the body in health and disease, and the application of the diverse, functionally graded, and hierarchical structures that they present to bioinspired engineering materials are reviewed. A range of such bioinspired engineering materials and associated manufacturing technologies that are on the horizon in interfacial tissue engineering, hydrogel bioadhesion at the interfaces, and healthcare and medical devices are described.

Immunomodulatory Blood-Derived Hybrid Hydrogels as Multichannel Microenvironment Modulators for Augmented Bone Regeneration

Autologous blood-derived protein hydrogels have shown great promise in the field of personalized regenerative medicine. However, the inhospitable regenerative microenvironments, especially the unfavorable immune microenvironment, are closely associated with their limited tissue-healing outcomes. Herein, novel immunomodulatory blood-derived hybrid hydrogels (PnP-iPRF) are rationally designed and constructed for enhanced bone regeneration via multichannel regulation of the osteogenic microenvironment. Such double-network hybrid hydrogels are composed of clinically approved injectable platelet-rich fibrin (i-PRF) and polycaprolactone/hydroxyapatite composite nanofibers by using enriched polydopamine (PDA) as the anchor. The polycaprolactone component in PnP-iPRF provides a reinforced structure to stimulate osteoblast differentiation in a proper biomechanical microenvironment. Most importantly, the versatile PDA component in PnP-iPRF can not only offer high adhesion capacity to the growth factors of i-PRF and create a suitable biochemical microenvironment for sustained osteogenesis but also reprogram the osteoimmune microenvironment via the induction of M2 macrophage polarization to promote bone healing. The present study will provide a new paradigm to realize enhanced osteogenic efficacy by multichannel microenvironment regulations and give new insights into engineering high-efficacy i-PRF hydrogels for regenerative medicine.

Biological Fixation of Bioactive Bone Cement in Vertebroplasty: The First Clinical Investigation of Borosilicate Glass (BSG) Reinforced PMMA Bone Cement

PMMA bone cement has been clinically used for decades in vertebroplasty due to its high mechanical strength and satisfactory injectability. However, the interface between bone and PMMA is fragile and more prone to refracture in situ because PMMA lacks a proper biological response from the host bone with minimal bone integration and dense fibrous tissue formation. Here, we modified PMMA by incoporating borosilicate glass (BSG) with a dual glass network of [BO₃] and [SiO₄], which spontaneously modulates immunity and osteogenesis. In particular, the BSG modified PMMA bone cement (abbreviated as BSG/PMMA cement) provided an alkaline microenvironment that spontaneously balanced the activities between osteoclasts and osteoblasts. Furthermore, the trace elements released from the BSGs enhanced the osteogenesis to strengthen the interface between the host bone and the implant. This study shows the first clinical case after implantation of BSG/PMMA for three months using the dual-energy CT, which found apatite nucleation around PMMA instead of fibrous tissues, indicating the biological interface was formed. Therefore, BSG/PMMA is promising as a biomaterial in vertebroplasty, overcoming the drawback of PMMA by improving the biological response from the host bone.

A pH-Sensitive, Stretchable, Antibacterial Artificial Tongue Based on MXene Cross-Linked Ionogel

Dehydration has always been a confusing problem for a hydrogel exposed to air, which restricts its application in practical detection. While an ionogel with unique properties can lock water molecules efficiently due to its low vapor pressure, the design and development of an ionogel with excellent water-locking properties and stability to achieve satisfactory detection are thus highly desirable. In this work, a pH-sensitive, stretchable, antibacterial, and stable ionogel artificial tongue was fabricated through dual cross-linking. The artificial tongue consisted of MXene as a cross-linking agent, phenol red as an indicator, gelatin, N-(2-hydroxyethyl) acrylamide, and 1-butyl-3-methylimidazolium chloride as the three-dimensional polymer network. A small quantity of MXene was used as a cross-linker the first time to promote the initiator in the system to generate free radicals, accelerating the reaction process and the multilevel linkage among the polymers. Meanwhile, the indicator phenol red was introduced into the ionogel successfully for the first time, showing great stability in 5 weeks. After evaluation by the Brand-Altman analysis, it was found that the method of pH measurement using ionogels had good consistency with the pH meter measurement method. Additionally, the prepared ionogel presented excellent water retention, mechanical stretchability, antibacterial property, and stability, as well as good test results in the test of artificial simulated saliva, demonstrating great potential in clinical applications.

Research progress of bone-targeted drug delivery system on metastatic bone tumors

Bone metastases are common in malignant tumors and the effect of conventional treatment is limited. How to effectively inhibit tumor bone metastasis and deliver the drug to the bone has become an urgent issue to be solved. While bone targeting drug delivery systems have obvious advantages in the treatment of bone tumors. The research on bone-targeted anti-tumor therapy has made significant progress in recent years. We introduced the related tumor pathways of bone metastases. The tumor microenvironment plays an important role in metastatic bone tumors. We introduce a drug-loading systems based on different environment-responsive nanocomposites for anti-tumor and anti-metastatic research. According to the process of bone metastases and the structure of bone tissue, we summarized the information on bone-targeting molecules. Bisphosphate has become the first choice of bone-targeted drug delivery carrier because of its affinity with hydroxyapatite in bone. Therefore, we sought to summarize the bone-targeting molecule of bisphosphate to identify the modification effect on bone-targeting. And this paper discusses the relationship between bisphosphate bone targeting molecular structure and drug delivery carriers, to provide some new ideas for the research and development of bone-targeting drug delivery carriers. Targeted therapy will make a more outstanding contribution to the treatment of tumors.

PgC3Mg metal-organic cages functionalized hydrogels with enhanced bioactive and ROS scavenging capabilities for accelerated bone regeneration

The repair of large bone defects is an urgent problem in the clinic. Note that the disruption of redox homeostasis around bone defect sites might hinder the new bone reconstruction. The rational design of hydrogels for bone regeneration still faces the challenges of insufficient antioxidant capability and weak osteogenesis performance. Here, motivated by the versatile therapeutic functions of metal-organic cages, magnesium-seamed C-propylpyrogallol[4]arene (PgC₃Mg) functionalized biodegradable and porous gelatin methacrylate (GelMA) hydrogels are constructed. The novel metal-organic cages endow hydrogels with highly bioactive characteristics and strong reactive oxygen species (ROS)-scavenging ability owing to the simultaneous release of bioactive Mg²⁺ ions and antioxidant phenolic hydroxyl-rich moieties. The in vitro results reveal that the PgC₃Mg modified biocompatible hydrogels show higher expression of osteo-related genes and significantly eliminate the intracellular ROS levels of bone marrow-derived mesenchymal stem cells (BMSCs) against oxidative damage. Meanwhile, the bioactive and ROS scavenging hydrogels can accelerate bone regeneration in large cranial defects. Overall, this study may provide new insights into the designing of regenerative bone grafts with simultaneously enhanced osteogenic and antioxidant capabilities.

Appraising Adjuvant Endocrine Therapy in Hormone Receptor Positive HER2-Negative Breast Cancer—A Literature Review

Background: Approximately 75% of breast cancer (BC) is associated with luminal differentiation expressing endocrine receptors (ER). For ER+ HER2− tumors, adjuvant endocrine therapy (ET) is the cornerstone treatment. Although relapse events steadily continue, the ET benefits translate to dramatically lengthen life expectancy with bearable side-effects. This review of ER+ HER2− female BC outlines suitable adjuvant treatment strategies to help guide clinical decision making around appropriate therapy. Methods: A literature search was conducted in Embase, Medline, and the Cochrane Libraries, using ER+ HER−, ET BC keywords. Results: In low-risk patients: five years of ET is the standard option. While Tamoxifen remains the preferred selection for premenopausal women, AI is the choice for postmenopausal patients. In the high-risk category: ET plus/minus OFS with two years of Abemaciclib is recommended. Although extended ET for a total of ten years is an alternative, the optimal AI duration is undetermined; nevertheless an additional two to three years beyond the initial five years may be sufficient. In this postmenopausal group, bisphosphonate is endorsed. Conclusions: Classifying the risk category assists in deciding the treatment route and its optimal duration. Tailoring the breadth of ET hinges on a wide array of factors to be appraised for each individualized case, including weighing its benefits and harms.

Effects of Zinc, Magnesium, and Iron Ions on Bone Tissue Engineering

Large-sized bone defects are a great challenge in clinics and considerably impair the quality of patients' daily life. Tissue engineering strategies using cells, scaffolds, and bioactive molecules to regulate the microenvironment in bone regeneration is a promising approach. Zinc, magnesium, and iron ions are natural elements in bone tissue and participate in many physiological processes of bone metabolism and therefore have great potential for bone tissue engineering and regeneration. In this review, we performed a systematic analysis on the effects of zinc, magnesium, and iron ions in bone tissue engineering. We focus on the role of these ions in properties of scaffolds (mechanical strength, degradation, osteogenesis, antibacterial properties, etc.). We hope that our summary of the current research achievements and our notifications of potential strategies to improve the effects of zinc, magnesium, and iron ions in scaffolds for bone repair and regeneration will find new inspiration and breakthroughs to inspire future research.