Advancements in drug-loaded hydrogel systems for bone defect repair

Enhancing in vitro osteogenic differentiation of mesenchymal stem cells via sustained dexamethasone delivery in 3D-Printed hybrid scaffolds based on polycaprolactone-nanohydroxyapatite/alginate-gelatin for bone regeneration

Despite the natural ability of bone repair, its limitations have led to advanced organic-inorganic-based biomimetic scaffolds and sustained drug release approaches. Particularly, dexamethasone (DEX), a widely used synthetic glucocorticoid, has been shown to increase the expression of bone-related genes during the osteogenesis process. This study aims to develop a hybrid 3D-printed scaffold for controlled delivery of dexamethasone. Hence, hybrid scaffolds were fabricated using a layer-by-layer 3D-printing of combined materials comprising polycaprolactone (PCL)-nanohydroxyapatite (nHA) composite, and DEX-loaded PCL microparticles embedded in the alginate-gelatin hydrogel. Encapsulation efficiency, loading capacity, and in vitro kinetics of DEX release were evaluated. Osteogenic differentiation of human endometrial mesenchymal stem cells (hEnMSCs) on DEX-loaded hybrid scaffolds was assessed by evaluating osteogenic gene expression levels (collagen I, osteonectin, RUNX2), alkaline phosphatase (ALP) activity, and scaffold mineralization. The hybrid scaffolds exhibited favorable morphology, mechanical-properties, biocompatibility, and biodegradability, enhancing osteogenesis of hEnMSCs. DEX-loaded PCL microparticles within hybrid scaffolds exhibited a controlled release pattern and promoted osteogenic differentiation during the sustained release period through a significant increase in osteonectin and COL1A1 expression. Also, increased mineralization was demonstrated by SEM and alizarin red staining. This study proposes that drug-loaded 3D-printed hybrid organic-inorganic nanocomposite scaffolds are promising for advanced bone tissue engineering applications.

Natural polymer chitosan-based hydrogels can enhance mechanical properties and produce H2S gas by UV-light to treat scalded wound

The healing of deep second- and third-degree scald wounds is frequently impaired by inflammation, oxidative stress, vascular damage, and neural injury, creating substantial challenges for clinical wound management. To address this, we developed a novel hydrogel dressing strategy utilizing alpha-lipoic acid-modified chitosan (LAMC) combined with a four-armed polyethylene glycol derivative (PEG-NHS). This hydrogel achieves rapid wound coverage through its inherent adhesive properties, followed by ultraviolet (UV)-triggered secondary cross-linking to enhance mechanical stability (average compression strength reaches about 173 KPa). Concurrently, the hydrogel releases hydrogen sulfide (H₂S) gas, which exerts anti-inflammatory, antioxidant, pro-angiogenic, and neuroregenerative effects. Experimental data demonstrated that a 400 μL disulfide-containing hydrogel generated 28.89 ± 3.70 μM H₂S within 30 s of UV exposure. In vivo testing revealed a wound healing rate exceeding 95 % by day 14 in UV-treated hydrogel groups. The combination of these materials and their functional advantages provide a promising new way for the postoperative repair of severe scalded wounds.

Probiotics and nanoparticle-mediated nutrient delivery in the management of transfusion-supported diseases

Bone marrow is vital for hematopoiesis, producing blood cells essential for oxygen transport, immune defense, and clotting. However, disorders like leukemia, lymphoma, aplastic anemia, and myelodysplastic syndromes can severely disrupt its function, leading to life-threatening complications. Traditional treatments, including chemotherapy and stem cell transplants, have significantly improved patient outcomes but are often associated with severe side effects and limitations, necessitating the exploration of safer, more targeted therapeutic strategies. Nanotechnology has emerged as a promising approach for addressing these challenges, particularly in the delivery of nutraceuticals-bioactive compounds derived from food sources with potential therapeutic benefits. Despite their promise, nutraceuticals often face clinical limitations due to poor bioavailability, instability, and inefficient delivery to target sites. Nanoparticles offer a viable solution by enhancing the stability, absorption, and targeted transport of nutraceuticals to bone marrow while minimizing systemic side effects. This study explores a range of bone marrow disorders, conventional treatment modalities, and the potential of nanoparticles to enhance nutraceutical-based therapies. By improving targeted delivery and therapeutic efficacy, nanoparticles could revolutionize bone marrow disease management, providing patients with more effective and less invasive treatment options. These advancements represent a significant step toward safer and more efficient therapeutic approaches, ultimately improving patient prognosis and overall health.

Sequential drug release nanocomposites for synergistic therapy in disease treatment

Time-sequenced drug release, or sequential drug release, represents a pivotal strategy in the synergistic treatment of diseases using nanocomposites. Achieving this requires the rational integration of multiple therapeutic agents within a single nanocomposite, coupled with precise time-controlled release mechanisms. These nanocomposites offer many advantages, including enhanced therapeutic synergy, reduced side effects, attenuated adverse interactions, improved stability and optimized drug utilization. Consequently, research in the field of drug delivery and synergistic therapy has become increasingly important. Currently, sequential drug release research is still in the data collection and basic research stages, and its potential has not yet been fully explored. Although prior studies have explored the sequential drug release strategy in various contexts, a comprehensive review of the underlying mechanisms and their applications in nanocomposites remains scarce. This review categorizes different types of sequential drug release strategies and summarizes diverse nanocomposites, focusing on both physical approaches driven by structural variations and chemical methods based on stimulus-responsive mechanisms. Furthermore, we highlight the major applications of sequential drug release strategies in the treatment of various diseases and detail their therapeutic efficacy. Finally, emerging trends and challenges in advancing sequential drug release strategies based on nanocomposites for disease treatment are also discussed.

ALP-Mimetic Cyclic Peptide Nanotubes: A Multifunctional Strategy for Osteogenesis and Bone Regeneration

Alkaline phosphatase (ALP) plays a crucial role in bone mineralization by hydrolyzing organophosphates and releasing inorganic phosphate ions, facilitating hydroxyapatite formation. The imidazole ring in the functional domain of ALP is critical for its catalytic activity and bone mineralization. However, the therapeutic application of native ALP is hindered by instability, short half-life, immunogenicity, and variable efficacy. This work presents the development of ALP-mimetic cyclic-octapeptide (ALAKHKHP) nanotubes to promote osteogenic differentiation and bone mineralization. The incorporation of imidazole-rich histidine residues in close proximity gives enzyme-mimetic characteristics. The nanotubes effectively catalyzed para-nitrophenyl phosphate (pNPP) hydrolysis, promoting in vitro calcium deposition and ALP activity, which stimulated osteogenic differentiation of MC3T3-E1 preosteoblasts, as evidenced by the upregulation of osteogenic marker genes. The nanotubes demonstrated excellent cell migration, reactive oxygen species (ROS) scavenging, and anti-inflammatory properties. This biomimetic nanoscaffold provides a promising alternative for bone regeneration, without relying on native enzymes, growth factors, or drugs.

Polydopamine Nanocomposite Hydrogel for Drug Slow-Release in Bone Defect Repair: A Review of Research Advances

In recent years, hydrogels have emerged as promising candidates for bone defect repair due to their excellent biocompatibility, high porosity, and water-retentive properties. However, conventional hydrogels face significant challenges in clinical translation, including brittleness, low mechanical strength, and poorly controlled drug degradation rates. To address these limitations, as a multifunctional polymer, polydopamine (PDA) has shown great potential in both bone regeneration and drug delivery systems. Its robust adhesive properties, biocompatibility, and responsiveness to photothermal stimulation make it an ideal candidate for enhancing hydrogel performance. Integrating PDA into conventional hydrogels not only improves their mechanical properties but also creates an environment conducive to cell adhesion, proliferation, and differentiation, thereby promoting bone defect repair. Moreover, PDA facilitates controlled drug release, offering a promising approach to optimizing treatment outcomes. This paper first explores the mechanisms through which PDA promotes bone regeneration, laying the foundation for its clinical translation. Additionally, it discusses the application of PDA-based nanocomposite hydrogels as advanced drug delivery systems for bone defect repair, providing valuable insights for both research and clinical translation.

Multifunctional hydrogel scaffolds based on polysaccharides and polymer matrices promote bone repair: A review

With the advancement of medical technology, the utilization of bioactive materials to promote bone repair has emerged as a significant research area. Hydrogels, as biomaterials, play a crucial role in bone tissue engineering. These hydrogels exhibit high biocompatibility, providing in vivo ecological conditions conducive to cell survival, and offer substantial advantages in facilitating bone repair. Different matrices of hydrogels serve distinct functions. In recent years, numerous researchers have developed a variety of novel hydrogel materials utilizing diverse matrices. These materials not only enhance the osteogenic induction capacity of hydrogels but also improve their efficacy as scaffolds in the treatment of complex bone defects, such as those resulting from trauma, tumor resection, or large bone defects due to infection. This article primarily analyzes the role of hydrogels that utilize polysaccharides and polymers as matrices in bone tissue repair, focusing on the creation of an optimal microenvironment to promote bone regeneration. These investigations deepen the understanding of the mechanisms underlying the action of hydrogels and establish a foundation for future advancements in the biomedical field.

[Research progress on bone repair biomaterials with the function of recruiting endogenous mesenchymal stem cells]

Objective

To review the research progress on bone repair biomaterials with the function of recruiting endogenous mesenchymal stem cells (MSCs).

Methods

An extensive review of the relevant literature on bone repair biomaterials, particularly those designed to recruit endogenous MSCs, was conducted, encompassing both domestic and international studies from recent years. The construction methods and optimization strategies for these biomaterials were summarized. Additionally, future research directions and focal points concerning this material were proposed.

Results

With the advancement of tissue engineering technology, bone repair biomaterials have increasingly emerged as an ideal solution for addressing bone defects. MSCs serve as the most critical "seed cells" in bone tissue engineering. Historically, both MSCs and their derived exosomes have been utilized in bone repair biomaterials; however, challenges such as limited sources of MSCs and exosomes, low survival rates, and various other issues have persisted. To address these challenges, researchers are combining growth factors, bioactive peptides, specific aptamers, and other substances with biomaterials to develop constructs that facilitate stem cell recruitment. By optimizing mechanical properties, promoting vascular regeneration, and regulating the microenvironment, it is possible to create effective bone repair biomaterials that enhance stem cell recruitment.

Conclusion

In comparison to cytokines, phages, and metal ions, bioactive peptides and aptamers obtained through screening exhibit more specific and targeted recruitment functions. Future development directions for bone repair biomaterials will involve the modification of peptides and aptamers with targeted recruitment capabilities in biological materials, as well as the optimization of the mechanical properties of these materials to enhance vascular regeneration and adjust the microenvironment.

Production of a magnetic nanocomposite for biological and hyperthermia applications based on chitosan-silk fibroin hydrogel incorporated with carbon nitride

Hydrogels based on natural polymers have lightened the path of novel drug delivery systems, wound healing, and tissue engineering fields because they are renewable, non-toxic, biocompatible, and biodegradable. Furthermore, applying modified hydrogels can upgrade their biological activity. Herein, Chitosan (CS) was used to create a hydrogel using terephthaloyl thiourea as a cross-linker. Silk fibroin (SF) and carbon nitride (CN) were added to the hydrogel to enhance its strength and biocompatibility. Finally, CS hydrogel/SF/CN was in situ magnetized using Fe3O4 magnetic nanoparticles (MNPs) and manufactured as a nanobiocomposite for improved hyperthermia. The structural properties of the nanobiocomposite were assessed using several analytical techniques, including VSM, FTIR, TGA, EDX, XRD, and FESEM. The saturation magnetization of this magnetic nanocomposite was 23.94 emu/g. The hemolytic experiment on the nanobiocomposite resulted in ca. 98 % cell survival, with a hemolysis rate of 1.69 %. Anticancer property is confirmed by a 20.0 % reduction in cell viability of BT549 cells at 1.75 mg/mL concentration compared to 0.015 mg/mL. The nanocomposite is non-toxic to the human embryonic kidney cell line (HEK293T), indicating its potential for biomedical applications. Finally, the magnetic nanocomposite's hyperthermia behavior was examined using a specific absorption rate (SAR), achieving the highest value of 47.44 W/g at 200.0 kHz. When subjected to an alternating magnetic field, the nanobiocomposite may perform well in hyperthermia therapy. These results indicate that the magnetic nanobiocomposite has the potential to perform well in hyperthermia therapy when subjected to an alternating magnetic field.

Nicorandil-based hydrogel promotes bone defect reconstruction by targeting Hmox1

BACKGROUND

The local use of drugs to promote bone healing is still difficult to apply clinically. We aimed to construct a nicorandil-based hydrogel to promote local bone healing by promoting angiogenesis and inhibiting osteoclastogenesis.

RESULTS

In this study, we constructed a nicorandil-based hydrogel and used it to intervene in bone repair during bone defect reconstruction. The results showed that the nicorandil-based hydrogel significantly inhibited osteoclast differentiation and promoted angiogenesis in vitro. Furthermore, bone formation was significantly promoted by the use of a nicorandil-based hydrogel. Mechanistically, Hmox1 was directly targeted by nicorandil, and overexpression of Hmox1 was found to promote bone defect reconstruction.

CONCLUSION

Our study provides a fresh perspective and a potential therapeutic approach for the use of local nicorandil-based hydrogels to improve bone defect reconstruction.

Dual-functional Hydroxyapatite scaffolds for bone regeneration and precision drug delivery

Addressing infected bone defects remains a significant challenge in orthopedics, requiring effective infection control and bone defect repair. A promising therapeutic approach involves the development of dual-functional engineered biomaterials with drug delivery systems that combine antibacterial properties with osteogenesis promotion. The Hydroxyapatite composite scaffolds offer a one-stage treatment, eliminating the need for multiple surgeries and thereby streamlining the process and reducing treatment time. This review delves into the impaired bone repair mechanisms within pathogen-infected and inflamed microenvironments, providing a theoretical foundation for treating infectious bone defects. Additionally, it explores composite scaffolds made of antibacterial and osteogenic materials, along with advanced drug delivery systems that possess both antibacterial and bone-regenerative properties. By offering a comprehensive understanding of the microenvironment of infectious bone defects and innovative design strategies for dual-function scaffolds, this review presents significant advancements in treatment methods for infectious bone defects. Continued research and clinical validation are essential to refine these innovations, ensuring biocompatibility and safety, achieving controlled release and stability, and developing scalable manufacturing processes for widespread clinical application.

The balance between helper T 17 and regulatory T cells in osteoimmunology and relevant research progress on bone tissue engineering

BACKGROUND

Bone regeneration is a well-regulated dynamic process, of which the prominent role of the immune system on bone homeostasis is more and more revealed by recent research. Before fully activation of the bone remodeling cells, the immune system needs to clean up the microenvironment in facilitating the bone repair initiation. Furthermore, this microenvironment must be maintained properly by various mechanisms over the entire bone regeneration process.

OBJECTIVE

This review aims to summarize the role of the T-helper 17/Regulatory T cell (Th17/Treg) balance in bone cell remodeling and discuss the relevant progress in bone tissue engineering.

RESULTS

The role of the immune response in the early stages of bone regeneration is crucial, especially the impact of the Th17/Treg balance on osteoclasts, mesenchymal stem cells (MSCs), and osteoblasts activity. By virtue of these knowledge advancements, innovative approaches in bone tissue engineering, such as nano-structures, hydrogel, and exosomes, are designed to influence the Th17/Treg balance and thereby augment bone repair and regeneration.

CONCLUSION

Targeting the Th17/Treg balance is a promising innovative strategy for developing new treatments to enhance bone regeneration, thus offering potential breakthroughs in bone injury clinics.

Evolution of Hybrid Hydrogels: Next-Generation Biomaterials for Drug Delivery and Tissue Engineering

Hydrogels, being hydrophilic polymer networks capable of absorbing and retaining aqueous fluids, hold significant promise in biomedical applications owing to their high water content, permeability, and structural similarity to the extracellular matrix. Recent chemical advancements have bolstered their versatility, facilitating the integration of the molecules guiding cellular activities and enabling their controlled activation under time constraints. However, conventional synthetic hydrogels suffer from inherent weaknesses such as heterogeneity and network imperfections, which adversely affect their mechanical properties, diffusion rates, and biological activity. In response to these challenges, hybrid hydrogels have emerged, aiming to enhance their strength, drug release efficiency, and therapeutic effectiveness. These hybrid hydrogels, featuring improved formulations, are tailored for controlled drug release and tissue regeneration across both soft and hard tissues. The scientific community has increasingly recognized the versatile characteristics of hybrid hydrogels, particularly in the biomedical sector. This comprehensive review delves into recent advancements in hybrid hydrogel systems, covering the diverse types, modification strategies, and the integration of nano/microstructures. The discussion includes innovative fabrication techniques such as click reactions, 3D printing, and photopatterning alongside the elucidation of the release mechanisms of bioactive molecules. By addressing challenges, the review underscores diverse biomedical applications and envisages a promising future for hybrid hydrogels across various domains in the biomedical field.