Angiogenesis in bone tissue engineering via ceramic scaffolds: A review of concepts and recent advancements

Multi-omics insights into bone tissue injury and healing: bridging orthopedic trauma and regenerative medicine

To preserve functionality, bone is an active tissue that can constantly reconstruct itself through modeling and remodeling. It plays critical roles in the body, including maintaining mineral homeostasis, serving as the adult human body's core site of hematopoiesis, and supporting the structures of the body's soft tissues. It possesses the natural regeneration capacity, but large and complex lesions often require surgical intervention. Multiple omics integrate proteomics, metabolomics, genomics, and transcriptomics to provide a comprehensive understanding of biological processes like bone tissue injury and healing in bone tissue regeneration and engineering. Recently, bone tissue engineering and regenerative medicines have offered promising tools for bone regeneration using a multi-omics approach. Thus, this article will highlight the role of multiple omics in understanding bone tissue injury and healing. It will discuss the role of bone tissue engineering in developing bone substitutes that can replace translational medicine. Lastly, new developments in bone tissue engineering and regenerative medicine, along with multi-omics approaches, offer promising tools for bone regeneration.

Construction of Cells-Membrane-Cells Living Complexes for Cartilage Repair by Enhancing the Structural Stability of Fibrous Membranes

3D cartilage tissue engineering scaffolds with stable structures are crucial for promoting cartilage tissue growth and repair. However, limited research attention is given to the effects of 3D cells-membrane-cells sandwich-like living complexes with enhanced structural stability for cartilage repair. In this study, silk fibroin/graphene oxide@kartogenin (SF/GO@KGN) fibrous membranes with improved structural stability are developed through the regulation of the crystallinity, and living complexes are constructed for cartilage repair using rat bone marrow stromal cells (rBMSCs) and the SF/GO@KGN fibrous membranes. Results show that the physicochemical properties of the SF/GO@KGN fibrous membranes, including morphology, tensile strength, swelling ratio, degradation, and KGN release rate are greatly influenced by the crystallinity of the fibrous membranes. The enhanced structural stability of the fibrous membranes promotes the adhesion, proliferation, and chondrogenic differentiation of rBMSCs on the surface of the fibrous membranes, as well as the deposition of the cartilage's extracellular matrix (ECM). Animal experiments demonstrate that sandwich-like cells-membrane-cells living complexes with high structural stability significantly promote early cartilage formation and ECM deposition. This study not only provides a facile and effective strategy for cartilage regeneration and repair but also provides new insights for designing and preparing other tissue engineering scaffolds.

Advanced alginate/58S bioactive glass inks with enhanced printability, mechanical strength, and cytocompatibility for soft tissue engineering

Alginate-based hydrogels are promising biomaterials for extrusion-based bioprinting; however, their poor mechanical properties, printability, and shape integrity limit their utility in mimicking complex tissues and organs. In this study, a novel sodium alginate (Alg)/58S bioactive glass (BG)-based ink was developed for soft tissue engineering applications. The inks were characterised for shear-thinning, flowability, and shape integrity by printing various structures, including single filaments (0° and 90° nozzle movement), scaffolds, and rings. The ABG10 ink (10 wt% 58S BG in Alg) exhibited superior printability, achieving a printing accuracy of over 90 %, compared to a printing accuracy of 30-40 % for pure Alg. Fourier transform infrared spectroscopy revealed interactions between 58S BG and the Alg matrix, while scanning electron microscopy characterised the 58S BG morphology within the matrix. The storage modulus increased from 767 (pure Alg) to 13,604 Pa (ABG10), while compressive strength rose from 23 ± 3 to 43 ± 4 kPa (58 % enhancement). The cytocompatibility of the inks was assessed using an MTT assay (with SH-SY5Y cells), which confirmed that ABG10 ink supports cell viability. Overall, ABG10 hydrogel-based inks exhibited enhanced shear-thinning behaviour, printability, mechanical strength, and cytocompatibility, which could help to develop patient-specific soft tissues.

Current Utilization of Gel-Based Scaffolds and Templates in Foot and Ankle Surgery-A Review

As tissue engineering and regenerative medicine (TERM) continues to revolutionize medicine and surgery, there is also growing interest in applying these advancements to foot and ankle surgery. The purpose of this article is to provide a comprehensive review of the types of gel scaffolds and templates, their applications in foot and ankle surgery, the challenges with current utilization, and the future directions of TERM in foot and ankle surgery. With multiple compelling scaffold prospects across the numerous natural, synthetic, and hybrid polymers currently utilized in TERM, promising results have been described in the treatment of osteoarthritis (OA) and osteochondral lesions (OCLs). However, concerns with material biocompatibility, structural integrity, feasibility during surgery, and degradation still exist and limit the extent of utilization. As researchers continue to develop enhanced polymers and formulations that address current issues, there are many opportunities to increase applications across foot and ankle surgery.

Advancement of Nanomaterials- and Biomaterials-Based Technologies for Wound Healing and Tissue Regenerative Applications

Patients and healthcare systems face significant social and financial challenges due to the increasing number of individuals with chronic external and internal wounds that fail to heal. The complexity of the healing process remains a serious health concern, despite the effectiveness of conventional wound dressings in promoting healing. Recent advancements in materials science and fabrication techniques have led to the development of innovative dressings that enhance wound healing. To further expedite the healing process, novel approaches such as nanoparticles, 3D-printed wound dressings, and biomolecule-infused dressings have emerged, along with cell-based methods. Additionally, gene therapy technologies are being harnessed to generate stem cell derivatives that are more functional, selective, and responsive than their natural counterparts. This review highlights the significant potential of biomaterials, nanoparticles, 3D bioprinting, and gene- and cell-based therapies in wound healing. However, it also underscores the necessity for further research to address the existing challenges and integrate these strategies into standard clinical practice.

Natural Protein-Based Multifunctional Hydrogel Dressing Formed by Rapid Photocuring and Zinc Ion Coordination to Accelerate Wound Healing

This study explores the use of chicken egg white (EW), a rich source of natural proteins, to address challenges in wound healing management. Herein, a novel Zn2+-infused EW/GelMA (EW/Gel) hybrid hydrogel is developed, featuring an interpenetrating network (IPN) structure, where the first network consists of photo-cross-linked GelMA and the second network consists of Zn2+-infused EW (Zn-EW) through ion-protein binding. By optimizing the design and formulation, the resulting Zn-EW/Gel hydrogel exhibited enhanced mechanical stability and self-adhesive properties. In vitro experiments demonstrated that the combined effects of functional proteins and active ions within the Zn-EW/Gel hydrogel promote fibroblast proliferation and type I collagen expression, modulate the immune microenvironment, and enhance angiogenesis. The hydrogel also demonstrated excellent biocompatibility and bioactivity in vivo, showing strong promise for restoring the physiological properties of the damaged wound tissue.

Bioceramic Surface Topography Regulating Immune Osteogenesis

Objective: This study aims to clarify the effects of bioceramic interface cues on macrophages. Impact Statement: Recently, there have been many researches exploring the effects of interface topography cues on macrophage polarization and cytokine secretion. However, the effects and underlying mechanisms of bioceramic interface cues on macrophages still need exploring. This study provides insights into the effects of bioceramic micro-groove surface structures on macrophages. Introduction: With the development of bone tissue engineering methods, bioceramics have been used for bone repair. After the implantation of bioceramics, innate immune response that occurs at the interface of materials can deeply influence the subsequent inflammation and bone regeneration progress. Therefore, the exploration and regulation of immune response of the bioceramic interface will be beneficial to promote the bone regeneration effects. Methods: In this study, bioceramics with micro-groove structures on the surface are fabricated by digital light processing 3-dimensional printing technology. Then, micro-groove structures with different spacings (0, 25, 50, and 75 μm) are prepared separately to explore the effects on macrophages. Results: The large spacing micro-groove structure can promote the M2 polarization and osteoinductive cytokine secretion of macrophage. The reason is that the large spacing micro-groove structure can induce directional arrangement of macrophage so as to change the phenotype and cytokine secretion. Further researches show that macrophage of the large spacing micro-groove structure can promote the osteogenic differentiation of bone mesenchymal stem cells, which can benefit osteogenesis and osteointegration. Conclusion: This study offers an effective and application potential method for bone repair.

Strontium-Substituted Nanohydroxyapatite Containing Biodegradable 3D Printed Composite Scaffolds for Bone Regeneration

Treatment of large-size bone defects is difficult, and acquiring autografts may be challenging due to limited availability. A synthetic patient-specific bone substitute can be developed by using 3D printing technologies in such cases. In the present study, we have developed photocurable composite resins with poly(trimethylene carbonate) (PTMC) containing a high percentage of biodegradable bioactive strontium-substituted nanohydroxyapatite (SrHA, size 30-70 nm). These photocurable resins have then been employed to develop high-surface-area 3D-printed bone substitutes using the digital light processing (DLP) technique. To enhance the surface area of the 3D-printed substitute, cryogels alone and functionalized with bioactive components of bone morphogenetic protein (BMP) and zoledronic acid (ZA) were filled within the 3D-printed scaffold/substitute. The scaffolds were tested in vitro for biocompatibility and functionality in vivo in two therapeutically relevant rat models with large bone defects (4 mm). The porosities of 3D printed scaffolds were found to be 60.1 ± 0.9%, 72.9 ± 0.5%, and 74.3 ± 1.6% for PTMC, PTMC-HA, and PTMC-SrHA, respectively, which is in the range of cancellous bone (50-95%). The thermogravimetric analysis demonstrated the fabrication of 3D printed composites with HA and SrHA concentrations of 51.5 and 57.4 wt %, respectively, in the PTMC matrix. The tensile Young's modulus (E), compressive moduli, and wettability increased post incorporation of SrHA and HA in the PTMC matrix. In vitro and in vivo results revealed that SrHA integrated into the PTMC matrix exhibited good physicochemical and biological properties. Furthermore, the osteoactive molecule-functionalized 3D printed composite scaffolds were found to have an adequate osteoconductive and osteoinductive surface that has shown increased bone regeneration and defect repair in both tibial and cranial bone defects. Our findings thus support the use of PTMC-SrHA composites as next-generation patient-specific synthetic bioactive biodegradable bone substitutes.

Highly porous sildenafil loaded polylactic acid/polyvinylpyrrolidone based 3D printed scaffold containing forsterite nanoparticles for craniofacial reconstruction

Tissue engineering has emerged as a promising substitute for traditional tissue repair methods. Nowadays, advancements in 3D printing technology have enabled the fabrication of customized scaffolds to support tissue regeneration. In the present study, a polylactic acid-polyvinylpyrrolidone 3D-printed scaffold containing 10 % forsterite was fabricated. Subsequently, lyophilized fucoidan microstructures loaded with sildenafil were filled the channels of this 3D-printed scaffold. The fabricated scaffold loaded with sildenafil was thoroughly characterized, revealing that 97.46 % of the loaded sildenafil was released in a sustained manner over 28 days. Furthermore, the biocompatibility of MG63 was evaluated through cell viability and adhesion tests. The findings indicated a direct and favorable influence on cell behavior. Based on the chicken chorioallantoic membrane assay, the fabricated scaffold significantly increases angiogenesis due to the sustained release of sildenafil. Moreover, in-vivo studies conducted on a rat model demonstrated that the 3D-printed scaffold was able to stimulate and accelerate the repair of calvarial defects within 8 weeks, and the amount of new bone tissue formation was significantly higher than that of other experimental groups. Based on the comprehensive in-vitro and in-vivo assessments, the scaffold with a macro- and microporous structure combined with the ability to release sildenafil is suggested as a potential candidate for repairing bone tissue, especially in the context of skull defects.

Fabrication and Biomedical Application of Alginate Composite Hydrogels in Bone Tissue Engineering: A Review

Nowadays, as a result of the frequent occurrence of accidental injuries and traumas such as bone damage, the number of people causing bone injuries or fractures is increasing around the world. The design and fabrication of ideal bone tissue engineering (BTE) materials have become a research hotspot in the scientific community, and thus provide a novel path for the treatment of bone diseases. Among the materials used to construct scaffolds in BTE, including metals, bioceramics, bioglasses, biomacromolecules, synthetic organic polymers, etc., natural biopolymers have more advantages against them because they can interact with cells well, causing natural polymers to be widely studied and applied in the field of BTE. In particular, alginate has the advantages of excellent biocompatibility, good biodegradability, non-immunogenicity, non-toxicity, wide sources, low price, and easy gelation, enabling itself to be widely used as a biomaterial. However, pure alginate hydrogel as a BTE scaffold material still has many shortcomings, such as insufficient mechanical properties, easy disintegration of materials in physiological environments, and lack of cell-specific recognition sites, which severely limits its clinical application in BTE. In order to overcome the defects of single alginate hydrogels, researchers prepared alginate composite hydrogels by adding one or more materials to the alginate matrix in a certain proportion to improve their bioapplicability. For this reason, this review will introduce in detail the methods for constructing alginate composite hydrogels, including alginate/polymer composite hydrogels, alginate/bioprotein or polypeptide composite hydrogels, alginate/bioceramic composite hydrogels, alginate/bioceramic composite hydrogels, and alginate/nanoclay composite hydrogels, as well as their biological application trends in BTE scaffold materials, and look forward to their future research direction. These alginate composite hydrogel scaffolds exhibit both unexceptionable mechanical and biochemical properties, which exhibit their high application value in bone tissue repair and regeneration, thus providing a theoretical basis for the development and sustainable application of alginate-based functional biomedical materials.

Enhanced mechanical properties and biocompatibility of hydroxyapatite scaffolds by magnesium and titanium oxides for bone tissue applications

Significant attention has been devoted to bioactive implants for bone tissue applications, particularly composite scaffolds based on hydroxyapatite (HaP). This study explores the effects of Magnesium and Titanium oxides on the characteristics of HaP-based composite (HMT) scaffolds. The ceramic nanopowders were synthesized using in situ sol-gel, and then the scaffolds were fabricated by gel-casting technique, followed by heat treatment at 1200 °C. The thermal, microstructural, and structural properties of the samples were investigated by different characterization techniques. It was observed that the formation of the MgTiO3 phase in the composite scaffold was likely the key factor contributing to the improved mechanical properties. Finally, to evaluate bioactivity and biodegradability, scaffolds were immersed in simulated body fluid (SBF) buffer and analyzed by Field Emission Scanning Electron Microscopy (FESEM), and the viability of human fibroblast cells was assessed using the MTT assay. The composite scaffolds containing the MgTiO3 phase showed greater HaP layer formation on the scaffold surface, indicating enhanced biocompatibility.

Deferoxamine-Loaded Chitosan-Based Hydrogel on Bone Implants Showing Enhanced Bond Strength and Pro-Angiogenic Effects

Angiogenesis is vital for bone fracture healing and plays a significant role in the fate of orthopedic implants. The growth and maintenance of new blood vessels at the fracture site of patients is essential, which promotes the clinical outcome of plasma sprayed Ti (PST) coated orthopedic implants. In order to endow the PST coating with pro-angiogenic effects, deferoxamine-loaded chitosan-based hydrogel was fabricated on the coating surface. Polydopamine-modified chitosan (CS/PDA) hydrogel exhibited enhanced bonding strength to PST coatings as evidenced by scratch test. The deferoxamine-loaded CS/PDA (CS/PDA-DFO) exhibited a sustained drug-release property, and the cumulative concentration of released DFO reached 20.21 μg/mL on day 7. PST-CS/PDA with higher wettability and active group quantity enhanced the viability and adhesion characteristics of human umbilical vein endothelial cells (HUVECs) and upregulated the secretion level of nitric oxide and vascular endothelial growth factor. Moreover, the introduction of DFO in PST-CS/PDA further enhanced the pro-angiogenic effects. Above all, this study offers a novel approach for developing hydrogel coating on orthopedic implants showing enhanced bonding strength and pro-angiogenic effects.