Recent Advances in Bioengineering Bone Revascularization Based on Composite Materials Comprising Hydroxyapatite

Advancements in Bone Replacement Techniques-Potential Uses After Maxillary and Mandibular Resections Due to Medication-Related Osteonecrosis of the Jaw (MRONJ)

Maxillofacial bone defects can have a profound impact on both facial function and aesthetics. While various biomaterial scaffolds have shown promise in addressing these challenges, regenerating bone in this region remains complex due to its irregular shape, intricate structure, and differing cellular origins compared to other bones in the human body. Moreover, the significant and variable mechanical loads placed on the maxillofacial bones add further complexity, especially in cases of difficult-to-treat medical conditions. This review provides a brief overview of medication-related osteonecrosis of the jaw (MRONJ), highlighting the medication-induced adverse reactions and the associated clinical challenges in treating this condition. The purpose of this manuscript is to emphasize the role of biotechnology and tissue engineering technologies in therapy. By using scaffold materials and biofactors in combination with autologous cells, innovative solutions are explored for the repair of damaged facial bones. The ongoing search for effective scaffolds that can address these challenges and improve in vitro bone preparation for subsequent regeneration in the maxillofacial region remains critical. The primary purpose of this review is to spotlight current research trends and novel approaches in this area.

3D printing of different fibres towards HA/PCL scaffolding induces macrophage polarization and promotes osteogenic differentiation of BMSCs

With the rise of bone tissue engineering (BET), 3D-printed HA/PCL scaffolds for bone defect repair have been extensively studied. However, little research has been conducted on the differences in osteogenic induction and regulation of macrophage (MPs) polarisation properties of HA/PCL scaffolds with different fibre orientations. Here, we applied 3D printing technology to prepare three sets of HA/PCL scaffolds with different fibre orientations (0-90, 0-90-135, and 0-90-45) to study the differences in physicochemical properties and to investigate the response effects of MPs and bone marrow mesenchymal stem cells (BMSCs) on scaffolds with different fibre orientations. The results showed that multi-angle staggered fibres affected the overall porosity and compressive strength of the scaffolds. Compared with the other two groups, the 0-90-45 scaffold induced osteogenic differentiation of BMSCs more significantly, while promoting the polarisation of MPs towards the M2 phenotype to form an osteogenic-friendly immune microenvironment. Unexpectedly, the 0-90-45 scaffold significantly upregulated the expression of angiogenic genes (PDGF, VEGF). Therefore, we conclude that the multi-angle interlaced fibres better mimic the physiological structure of cancellous bone, and that the excellent biomimetic properties reflect the best in vitro osteogenic, immunomodulatory and angiogenic effects. In conclusion, this study is a step forward in the exploration of BET scaffolds and provides a very promising bone filling material.

Design of patient-specific mandibular reconstruction plates and a hybrid scaffold

BACKGROUND

Managing segmental mandibular defects remains challenging, requiring a multidisciplinary approach despite the remarkable progress in mandibular reconstruction plates, finite element methods, computer-aided design and manufacturing techniques, and novel surgical procedures. Complex surgeries require a comprehensive approach, as using only reconstruction plates or tissue scaffolds may not be adequate for optimal results. The limitations of the treatment options should be investigated towards a patient-specific trend to provide shorter surgery time, better healing, and lower costs. Integrated hybrid scaffold systems are promising in improving mechanical properties and facilitating healing. By combining different materials and structures, hybrid scaffolds can provide enhanced support and stability to the tissue regeneration process, leading to better patient outcomes. The use of such systems represents a significant advancement in tissue engineering and a wide range of medical procedures.

MATERIALS AND METHODS

A head and neck computed tomography (CT) data of a patient with odontogenic myxoma was used for creating a three-dimensional (3D) mandible model. Virtual osteotomies were performed to create a segmental defect model, including the angulus mandibulae region. The first mandibular reconstruction plate was designed. Finite elemental analyses (FEA) and topology optimizations were performed to create two different reconstruction plates for different treatment scenarios. The FEA were performed for the resulting two plates to assess their biomechanical performance. To provide osteoconductive and osteoinductive properties a scaffold was designed using the defect area. A biomimetic Tricalcium phosphate-Polycaprolactone (TCP-PCL) hybrid bone scaffold enhanced with Hyaluronic acid dipping was manufactured.

RESULTS

The results of the in-silico analysis indicate that the designed reconstruction plates possess robust biomechanical performance and demonstrate remarkable stability under the most rigorous masticatory activities. Using the Voronoi pattern decreased the mass by %37 without losing endurance. Using reconstruction plates and hybrid scaffolds exhibits promising potential for clinical applications, subject to further in vivo and clinical studies.

Fluorinated Porcine Bone-Derived Hydroxyapatite Promotes Vascularized Osteogenesis by Coordinating Human Bone Marrow Mesenchymal Stem Cell/Human Umbilical Vein Endothelial Cell Complexes

Biogenic hydroxyapatite is known for its osteoinductive potential due to its similarity to human bone and biocompatibility, but insufficient vascularization compared to autogenous bone during early implantation limits bone integration and osteogenesis. Fluorine has been shown to improve hydroxyapatite's mechanical properties and the coupling of osteogenic and angiogenic cells. In this study, fluorine-modified biogenic hydroxyapatite (FPHA) with varying fluorine concentrations was prepared and tested for its ability to promote vascularized osteogenesis. FPHA prepared in this study retained the natural porous structure of biological cancellous bone and released F- ions when immersed in cell culture medium. The extraction solutions of FPHA0.25 and FPHA0.50 promoted the formation of capillary-like tubes by human umbilical vein endothelial cells (HUVECs), with FPHA0.25 significantly upregulating vegf mRNA and VEGF protein levels in co-cultured human bone marrow mesenchymal stem cells (HBMSCs). Additionally, FPHA0.25 and FPHA0.50 upregulated pdgf-bb mRNA and PDGF-BB protein levels in HUVECs. In vivo experiments using a rabbit cranial defect model demonstrated that FPHA0.25 promoted early bone formation and angiogenesis in the defect area, enhanced VEGF secretion, and increased PDGFR-β expression in endothelial and mesenchymal cells. These findings suggest that fluorine-modified biogenic hydroxyapatite with an optimal fluorine concentration (FPHA0.25) may offer a promising strategy to enhance the body's innate bone-healing potential by accelerating vascularization.

Polydopamine-functionalized calcium-deficient hydroxyapatite 3D-printed scaffold with sustained doxorubicin release for synergistic chemo-photothermal therapy of osteosarcoma and accelerated bone regeneration

Interior bone-tissue regeneration and rapid tumor recurrence post-resection are critical challenges in osteosarcoma and other bone cancers. Conventional bone tissue engineering scaffolds lack inhibitory effects on bone tumor recurrence. Herein, multifunctional scaffolds (named DOX/PDA@CDHA) were designed through the spontaneous polymerization of Dopamine (PDA) on the surface of Calcium Deficient Hydroxyapatite (CDHA) scaffolds, followed by in situ loading of the chemotherapeutic drug Doxorubicin (DOX). The PDA coating endowed the scaffolds with significant photothermal properties, while the gradual release of DOX provided an effective chemotherapeutic effect. The on-demand release of DOX at tumor sites, triggered by dual stimulation (near-infrared (NIR) light and the acidic pH typical of tumor microenvironments), specifically targets cancer cells, thereby mitigating systemic side effects. These unique characteristics facilitated effective osteosarcoma eradication both in vitro and in vivo. Moreover, the scaffold's composition, which mimics the mineral phase of natural bone and is enhanced by PDA's biocompatibility, promotes critical osteogenic and angiogenic processes. This facilitates not only tumor eradication but also the regeneration of healthy bone tissue. Collectively, this study presents a potent candidate for the regeneration of bone defects induced by osteosarcoma.

The Biomimetic Electrical Stimulation System Inducing Osteogenic Differentiations of BMSCs

Electrical stimulation has been used clinically as an adjunct therapy to accelerate the healing of bone defects, and its mechanism requires further investigations. The complexity of the physiological microenvironment makes it challenging to study the effect of electrical signal on cells alone. Therefore, an artificial system mimicking cell microenvironment in vitro was developed to address this issue. In this work, a novel electrical stimulation system was constructed based on polypyrrole nanowires (ppyNWs) with a high aspect ratio. Synthesized ppyNWs formed a conductive network in the composited hydrogel which contained modified gelatin with methacrylate, providing a conductive cell culture matrix for bone marrow mesenchymal stem cells. The dual-network conductive hydrogel had improved mechanical, electrical, and hydrophilic properties. It was able to imitate the three-dimensional structure of the cell microenvironment and allowed adjustable electrical stimulations in the following system. This hydrogel was integrated with cell culture plates, platinum electrodes, copper wires, and external power sources to construct the artificial electrical stimulation system. The optimum voltage of the electrical stimulation system was determined to be 2 V, which exhibited remarkable biocompatibility. Moreover, this system had significant promotion in cell spreading, osteogenic makers, and bone-related gene expression of stem cells. RNA-seq analysis revealed that osteogenesis was correlated to Notch, BMP/Smad, and calcium signal pathways. It was proven that this biomimetic system could regulate the osteogenesis procedure, and it provided further information about how the electrical signal regulates osteogenic differentiations.

Construction Form and Application of Three-Dimensional Bioprinting Ink Containing Hydroxyapatite

With the increasing prevalence of bone tissue diseases, three-dimensional (3D) bioprinting applied to bone tissue engineering for treatment has received a lot of interests in recent years. The research and popularization of 3D bioprinting in bone tissue engineering require bioinks with good performance, which is closely related to ideal material and appropriate construction form. Hydroxyapatite (HAp) is the inorganic component of natural bone and has been widely used in bone tissue engineering and other fields due to its good biological and physicochemical properties. Previous studies have prepared different bioinks containing HAp and evaluated their properties in various aspects. Most bioinks showed significant improvement in terms of rheology and biocompatibility; however, not all of them had sufficiently favorable mechanical properties and antimicrobial activity. The deficiencies in properties of bioink and 3D bioprinting technology limited the applications of bioinks containing HAp in clinical trials. This review article summarizes the construction forms of bioinks containing HAp and its modifications in previous studies, as well as the 3D bioprinting techniques adopted to print bioink containing HAp. In addition, this article summarizes the advantages and underlying mechanisms of bioink containing HAp, as well as its limitations, and suggests possible improvement to facilitate the development of bone tissue engineering bioinks containing HAp in the future.

Finite element analysis and in vitro tests on endurance life and durability of composite bone substitutes

Bone structures facilitate the regeneration and repair of bone tissue in regions where it has been damaged or destroyed, either temporarily or permanently. Therefore, the bone's fatigue strength and durability are crucial to its efficacy and longevity. Several variables, such as the construct's material qualities, design, and production procedure, loading and unloading cycles, and physiological conditions influence the endurance life of bone constructs. Metals, ceramics, and polymers are all routinely utilized to create bone substitutes, and each of these materials has unique features that might affect the fatigue strength and endurance life of the final product. The mechanical performance and capacity to promote bone tissue regeneration may be affected by the scaffold's design, porosity, and pore size. Researchers employ mechanical testing under cyclic loading circumstances as one example of an experimental approach used to assess bone construction endurance. These analyses can give us important information about the stress-strain behavior, resistance to multiple loading cycles, and fatigue strength of the new structure. Predicting the endurance life of the developed construct may also be possible with the use of simulations and numerical analyses. Hence, in order to create reliable and efficient constructs for bone tissue engineering, it is crucial to understand their fatigue strength and durability. The purpose of this study is to analyze the effective parameters for fatigue strength of bone structures and to gather the models and evaluations utilized in endurance life assessments.

Collagen-hydroxyapatite based scaffolds for bone trauma and regeneration: recent trends and future perspectives

Regenerative therapy, a key area of tissue engineering, holds promise for restoring damaged organs, especially in bone regeneration. Bone healing is natural to the body but becomes complex under stress and disease. Large bone deformities pose significant challenges in tissue engineering. Among various methods, scaffolds are attractive as they provide structural support and essential nutrients for cell adhesion and growth. Collagen and hydroxyapatite (HA) are widely used due to their biocompatibility and biodegradability. Collagen and nano-scale HA enhance cell adhesion and development. Thus, nano HA/collagen scaffolds offer potential solutions for bone regeneration. This review focuses on the use and production of nano-sized HA/collagen composites in bone regeneration.

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

The goal of this review is to present a wide range of hybrid formulations and composites containing calcium orthophosphates (abbreviated as CaPO4) that are suitable for use in biomedical applications and currently on the market. The bioactive, biocompatible, and osteoconductive properties of various CaPO4-based formulations make them valuable in the rapidly developing field of biomedical research, both in vitro and in vivo. Due to the brittleness of CaPO4, it is essential to combine the desired osteologic properties of ceramic CaPO4 with those of other compounds to create novel, multifunctional bone graft biomaterials. Consequently, this analysis offers a thorough overview of the hybrid formulations and CaPO4-based composites that are currently known. To do this, a comprehensive search of the literature on the subject was carried out in all significant databases to extract pertinent papers. There have been many formulations found with different material compositions, production methods, structural and bioactive features, and in vitro and in vivo properties. When these formulations contain additional biofunctional ingredients, such as drugs, proteins, enzymes, or antibacterial agents, they offer improved biomedical applications. Moreover, a lot of these formulations allow cell loading and promote the development of smart formulations based on CaPO4. This evaluation also discusses basic problems and scientific difficulties that call for more investigation and advancements. It also indicates perspectives for the future.

Calcium Phosphate Biomaterials for 3D Bioprinting in Bone Tissue Engineering

Three-dimensional bioprinting is a promising technology for bone tissue engineering. However, most hydrogel bioinks lack the mechanical and post-printing fidelity properties suitable for such hard tissue regeneration. To overcome these weak properties, calcium phosphates can be employed in a bioink to compensate for the lack of certain characteristics. Further, the extracellular matrix of natural bone contains this mineral, resulting in its structural robustness. Thus, calcium phosphates are necessary components of bioink for bone tissue engineering. This review paper examines different recently explored calcium phosphates, as a component of potential bioinks, for the biological, mechanical and structural properties required of 3D bioprinted scaffolds, exploring their distinctive properties that render them favorable biomaterials for bone tissue engineering. The discussion encompasses recent applications and adaptations of 3D-printed scaffolds built with calcium phosphates, delving into the scientific reasons behind the prevalence of certain types of calcium phosphates over others. Additionally, this paper elucidates their interactions with polymer hydrogels for 3D bioprinting applications. Overall, the current status of calcium phosphate/hydrogel bioinks for 3D bioprinting in bone tissue engineering has been investigated.

Comparison of different hydroxyapatite composites for bone tissue repair: In vitro and in vivo analyses

Objectives

The material used for bone tissue repair needs to be simultaneously osteoconductive, osteoinductive, and osteogenic. To overcome this problem, researchers combine hydroxyapatite (HA) with natural materials to improve properties. This paper compares the effects of angiogenesis and osteogenesis with different composites through in vivo experiments and characterization analysis.

Materials and Methods

Chitosan/nHA (CS/nHA) and sodium alginate/nHA (SA/nHA) microspheres were synthesized via reverse-phase emulsification crosslinking and analyzed using scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), and X-ray diffraction (XRD). Implanted into mouse thigh muscles, their angiogenic and osteogenic potentials were assessed after 8 and 12 weeks through various staining methods and immunohistochemistry.

Results

The mean vascular density (MVD) of CS/nHA, CaP/nHA, and SA/nHA groups was (134.92±35.30) n/mm2, (159.09±22.14) n/mm2, (160.31±42.23) n/mm2 at 12 weeks, respectively. The MVD of the CaP/nHA and SA/nHA groups were significantly higher than that of the CS/nHA group. The collagen volume fractions (CVF) were 34.13%, 51.53%, and 54.96% in the CS/nHA, CaP/nHA, and SA/nHA groups, respectively. In addition, the positive expression area ratios of OPN and CD31 in the CaP/nHA and SA/nHA groups were also significantly higher than those in the CS/nHA group.

Conclusion

The ability of SA/nHA composite microspheres in osteogenesis and angiogenesis is clearly superior to that of the CS/nHA group and is comparable to that of CaP/nHA, which has superior osteogenesis ability, indicating that SA/nHA composite microspheres have greater application prospects in bone tissue engineering.

Latest Research of Doped Hydroxyapatite for Bone Tissue Engineering

Bone tissue engineering has attracted great interest in the last few years, as the frequency of tissue-damaging or degenerative diseases has increased exponentially. To obtain an ideal treatment solution, researchers have focused on the development of optimum biomaterials to be applied for the enhancement of bioactivity and the regeneration process, which are necessary to support the proper healing process of osseous tissues. In this regard, hydroxyapatite (HA) has been the most widely used material in the biomedical field due to its great biocompatibility and similarity with the native apatite from the human bone. However, HA still presents some deficiencies related to its mechanical properties, which are essential for HA to be applied in load-bearing applications. Bioactivity is another vital property of HA and is necessary to further improve regeneration and antibacterial activity. These drawbacks can be solved by doping the material with trace elements, adapting the properties of the material, and, finally, sustaining bone regeneration without the occurrence of implant failure. Considering these aspects, in this review, we have presented some general information about HA properties, synthesis methods, applications, and the necessity for the addition of doping ions into its structure. Also, we have presented their influence on the properties of HA, as well as the latest applications of doped materials in the biomedical field.