Engineering Multifunctional Hydrogel With Osteogenic Capacity for Critical-Size Segmental Bone Defect Repair

Dynamic culturing of large cell-loaded PCL/gelatin methacryloyl scaffolds for bone critical size defect repair

Due to the limited ability to self-repair, the regeneration of bone critical-sized defects (CSD) is a significant challenge. Bone tissue engineering scaffolds are considered promising candidates for CSD repair, but low cell infiltration efficiency and a lack of nutrients greatly restrict bone regeneration abilities. Herein, we developed a dynamic culturing of large biomimetic bone scaffolds, PCL/GelMA@cells that combining 3D printed polycaprolactone (PCL) multi-channel cylinder with gelatin methacryloyl (GelMA) encapsulated with bone marrow mesenchymal stem cells (BMSCs) and rat aortic endothelial cells (RAECs). A cell dynamic culture system was fabricated to simulate the dynamic microenvironment. Compared to static culturing, dynamic culturing proved to enhance the nutrient exchange within the large scaffold to promote the cells infiltration, growth, proliferation and induce osteogenic and angiogenic differentiation. Furthermore, a rat cranial CSD (D = 10 mm) repair model verified the accelerated vascular ingrowth and new bone formation with the implantation of dynamic culturing of PCL/GelMA@cells scaffold (∼10 times higher than Blank group), indicating the great potential of dynamical culturing of scaffolds for bone repair. In summary, the results highlight the significant advantages of the dynamical culturing of cell-loaded scaffolds for bone regeneration, offering a promising strategy for addressing critical size bone defects.

Advancements in 3D gel culture systems for enhanced angiogenesis in bone tissue engineering

Angiogenesis-osteogenesis coupling is a crucial process in bone tissue engineering, requiring a suitable material structure for vessel growth. Recently, the 3D culture system has gained significant attention due to its benefits in cell growth, proliferation and tissue regeneration. Its most notable advantage is its ECM-like function, which supports endothelial cell adhesion and facilitates the formation of vascular-like networks-crucial for angiogenesis-osteogenesis coupling. Hydrogels, with their highly hydrophilic polymer network resembling the extracellular matrix, make the 3D gel culture system an ideal approach for angiogenesis due to its cellular integrity and adjustable properties. This article reviews the current use of 3D gel culture systems in bone tissue engineering, covering substrates, characteristics and processing technologies, thereby offering readers profound insights into these systems.

Bone Morphogenetic Protein 7-Loaded Gelatin Methacrylate/Oxidized Sodium Alginate/Nano-Hydroxyapatite Composite Hydrogel for Bone Tissue Engineering

Background

Bone tissue engineering (BTE) is a promising alternative to autologous bone grafting for the clinical treatment of bone defects, and inorganic/organic composite hydrogels as BTE scaffolds are a hot spot in current research. The construction of nano-hydroxyapatite/gelatin methacrylate/oxidized sodium alginate (nHAP/GelMA/OSA), abbreviated as HGO, composite hydrogels loaded with bone morphogenetic protein 7 (BMP7) will provide a suitable 3D microenvironment to promote cell aggregation, proliferation, and differentiation, thus facilitating bone repair and regeneration.

Methods

Dually-crosslinked hydrogels were fabricated by combining GelMA and OSA, while HGO hydrogels were formulated by incorporating varying amounts of nHAP. The hydrogels were physically and chemically characterized followed by the assessment of their biocompatibility. BMP7-HGO (BHGO) hydrogels were fabricated by incorporating suitable concentrations of BMP7 into HGO hydrogels. The osteogenic potential of BHGO hydrogels was then validated through in vitro experiments and using rat femoral defect models.

Results

The addition of nHAP significantly improved the physical properties of the hydrogel, and the composite hydrogel with 10% nHAP demonstrated the best overall performance among all groups. The selected concentration of HGO hydrogel served as a carrier for BMP7 loading and was evaluated for its osteogenic potential both in vivo and in vitro. The BHGO hydrogel demonstrated superior in vitro osteogenic induction and in vivo potential for repairing bone tissue compared to the outcomes observed in the blank control, BMP7, and HGO groups.

Conclusion

Using hydrogel containing 10% HGO appears promising for bone tissue engineering scaffolds, especially when loaded with BMP7 to boost its osteogenic potential. However, further investigation is needed to optimize the GelMA, OSA, and nHAP ratios, along with the BMP7 concentration, to maximize the osteogenic potential.

Macro, Micro, and Nano-Inspired Bioactive Polymeric Biomaterials in Therapeutic, and Regenerative Orofacial Applications

Introducing dental polymers has accelerated biotechnological research, advancing tissue engineering, biomaterials development, and drug delivery. Polymers have been utilized effectively in dentistry to build dentures and orthodontic equipment and are key components in the composition of numerous restorative materials. Furthermore, dental polymers have the potential to be employed for medication administration and tissue regeneration. To analyze the influence of polymer-based investigations on practical medical trials, it is required to evaluate the research undertaken in this sector. The present review aims to gather evidence on polymer applications in dental, oral, and maxillofacial reconstruction.

Applications of Degradable Hydrogels in Novel Approaches to Disease Treatment and New Modes of Drug Delivery

Hydrogels are particularly suitable materials for loading drug delivery agents; their high water content provides a biocompatible environment for most biomolecules, and their cross-linked nature protects the loaded agents from damage. During delivery, the delivered substance usually needs to be released gradually over time, which can be achieved by degradable cross-linked chains. In recent years, biodegradable hydrogels have become a promising technology in new methods of disease treatment and drug delivery methods due to their many advantageous properties. This review briefly discusses the degradation mechanisms of different types of biodegradable hydrogel systems and introduces the specific applications of degradable hydrogels in several new methods of disease treatment and drug delivery methods.

Functional hydrogels for the repair and regeneration of tissue defects

Tissue defects can be accompanied by functional impairments that affect the health and quality of life of patients. Hydrogels are three-dimensional (3D) hydrophilic polymer networks that can be used as bionic functional tissues to fill or repair damaged tissue as a promising therapeutic strategy in the field of tissue engineering and regenerative medicine. This paper summarises and discusses four outstanding advantages of hydrogels and their applications and advances in the repair and regeneration of tissue defects. First, hydrogels have physicochemical properties similar to the extracellular matrix of natural tissues, providing a good microenvironment for cell proliferation, migration and differentiation. Second, hydrogels have excellent shape adaptation and tissue adhesion properties, allowing them to be applied to a wide range of irregularly shaped tissue defects and to adhere well to the defect for sustained and efficient repair function. Third, the hydrogel is an intelligent delivery system capable of releasing therapeutic agents on demand. Hydrogels are capable of delivering therapeutic reagents and releasing therapeutic substances with temporal and spatial precision depending on the site and state of the defect. Fourth, hydrogels are self-healing and can maintain their integrity when damaged. We then describe the application and research progress of functional hydrogels in the repair and regeneration of defects in bone, cartilage, skin, muscle and nerve tissues. Finally, we discuss the challenges faced by hydrogels in the field of tissue regeneration and provide an outlook on their future trends.