Hydroxyapatite based biocomposite scaffold: A highly biocompatible material for bone regeneration

Towards MRI Study of Biointegration of Carbon-Carbon Composites with Ca-P Coatings

The development of specific MRI criteria to monitor the implantation process may provide valuable information of individual tissue response. Using MRI and histological methods, the biointegration of carbon-carbon (C-C) composites into the subcutaneous tissues of BDF1 mice and their biocompatibility were investigated. The study focused on autopsy specimens containing C-C composite implants, both uncoated and coated with synthetic hydroxyapatite (Ca-P) via electrodeposition or detonation techniques, assessed at 6 and 12 weeks post-implantation. The results revealed that the radiological characteristics of the connective tissue capsule surrounding the implants allowed for the differentiation between loose and dense connective tissues. Fat-suppressed T1-weighted MRI scans showed that the volume of both loose and dense connective tissue in the capsule increased proportionally at 6 and 12 weeks, with distinct ratios observed between the coated and uncoated specimens. The proposed MRI criteria provided a strategy for evaluating the density and homogeneity of the connective tissue capsule. This approach could be valuable for further non-invasive in vivo studies on implant biointegration.

Efficacy of a gelatin-based hemostatic sponge and hydroxyapatite-chitosan nanocomposites (nHAp/CS) on regeneration of radial bone defects in rabbits

Background

Bone-graft substitutes are a frequently employed method for the clinical reconstruction of osseous bone defects, and research on synthetic biomaterials is currently ongoing. Absorbable hemostatic gelatin sponge and hydroxyapatite-chitosan nanocomposites (nHAp/CS) have gained popularity in recent years because of their inherent characteristics: osteogenesis, osteoconductivity, osteoinductivity, biodegradability, and biocompatibility.

Aim

The aim of the study was to evaluate the effectiveness of 1) a gelatin-based hemostatic sponge (Surgispon) and 2) a combination of a weight ratio of 75/25 nHAp/CS composite with a Surgispon for osteogenic potential in the treatment of full-thickness segmental osseous defects in the radius of rabbits.

Methods

The 18 New Zealand rabbits had 10-mm-induced segmental diaphyseal defects of the left limb radius and were randomly allocated into three groups: group I left the defects untreated (control group), group II used a Surgispon, and group III had a weight ratio of 75/25 nHAp/CS composite wrapped with a Surgispon. Quantitative evaluation of the bone repair at the defect site in each group (n = 6), radiographic, gross, computed tomography (CT), and histopathological examinations were performed at 6 weeks (n = 3) and 12 weeks (n = 3) postoperatively.

Results

The quantitative statistical analysis of various evaluation methods at 6 weeks post-implantation demonstrated that there was no statistically significant difference between the groups (p > 0.05). The statistically significant differences (p < 0.05) between groups I and II, while groups I and III, were evident 12 weeks postoperatively.

Conclusion

The findings of the radiographic, macroscopic, CT, and histopathological analyses firmly demonstrate that the combination of a 75/25 weight ratio composite of nHAp/CS with Surgispon is more effective than Surgispon alone in its ability to significantly increase bone formation. This could provide a prospective option for treating segmental bone defects.

Efficacy of a gelatin-based hemostatic sponge and hydroxyapatite-chitosan nanocomposites (nHAp/CS) on regeneration of radial bone defects in rabbits

Background

Bone-graft substitutes are a frequently employed method for the clinical reconstruction of osseous bone defects, and research on synthetic biomaterials is currently ongoing. Absorbable hemostatic gelatin sponge and hydroxyapatite-chitosan nanocomposites (nHAp/CS) have gained popularity in recent years because of their inherent characteristics: osteogenesis, osteoconductivity, osteoinductivity, biodegradability, and biocompatibility.

Aim

The aim of the study was to evaluate the effectiveness of 1) a gelatin-based hemostatic sponge (Surgispon) and 2) a combination of a weight ratio of 75/25 nHAp/CS composite with a Surgispon for osteogenic potential in the treatment of full-thickness segmental osseous defects in the radius of rabbits.

Methods

The 18 New Zealand rabbits had 10-mm-induced segmental diaphyseal defects of the left limb radius and were randomly allocated into three groups: group I left the defects untreated (control group), group II used a Surgispon, and group III had a weight ratio of 75/25 nHAp/CS composite wrapped with a Surgispon. Quantitative evaluation of the bone repair at the defect site in each group (n = 6), radiographic, gross, computed tomography (CT), and histopathological examinations were performed at 6 weeks (n = 3) and 12 weeks (n = 3) postoperatively.

Results

The quantitative statistical analysis of various evaluation methods at 6 weeks post-implantation demonstrated that there was no statistically significant difference between the groups (p > 0.05). The statistically significant differences (p < 0.05) between groups I and II, while groups I and III, were evident 12 weeks postoperatively.

Conclusion

The findings of the radiographic, macroscopic, CT, and histopathological analyses firmly demonstrate that the combination of a 75/25 weight ratio composite of nHAp/CS with Surgispon is more effective than Surgispon alone in its ability to significantly increase bone formation. This could provide a prospective option for treating segmental bone defects.

Nanostructured polymer composites for bone and tissue regeneration

Nanostructured polymer composites have gained significant attention in recent years for their remarkable potential in bone and tissue regeneration. Moreover, with the integration of 3D printing technology, these composites hold promise for use in personalized medicine, where patient-specific scaffolds can be tailored to enhance therapeutic outcomes. Therefore, this review article aims to provide a comprehensive overview of the latest advancements in the development and application of nanostructured polymeric composites within the field of tissue engineering and bone regeneration. Here, the potential of biopolymers, natural polymers, and 3D-printed polymers to craft biocompatible, non-toxic, and mechanically robust composites is discussed in brief. Further, the fabrication techniques for 3D scaffolds and various forms of nanocomposites, including nanoparticles, nanocapsules, nanofibers, nanogels, and micelles for bone and tissue regeneration, are listed. Also, particular emphasis is placed on the role of nano-scaffolds and in situ hydrogels in bone and tissue regeneration. Overall, this review provides a concise and authoritative summary of the current state-of-the-art in nanostructured polymer composites for regenerative medicine, highlighting future directions and potential clinical applications.

In vitro evaluation of bone cell response to novel 3D-printable nanocomposite biomaterials for bone reconstruction

Critically-sized segmental bone defects represent significant challenges requiring grafts for reconstruction. 3D-printed synthetic bone grafts are viable alternatives to structural allografts if engineered to provide appropriate mechanical performance and osteoblast/osteoclast cell responses. Novel 3D-printable nanocomposites containing acrylated epoxidized soybean oil (AESO) or methacrylated AESO (mAESO), polyethylene glycol diacrylate, and nanohydroxyapatite (nHA) were produced using masked stereolithography. The effects of volume fraction of nHA and methacrylation of AESO on interactions of differentiated MC3T3-E1 osteoblast (dMC3T3-OB) and differentiated RAW264.7 osteoclast cells with 3D-printed nanocomposites were evaluated in vitro and compared with a control biomaterial, hydroxyapatite (HA). Higher nHA content and methacrylation significantly improved the mechanical properties. All nanocomposites supported dMC3T3-OB cells' adhesion and proliferation. Higher amounts of nHA enhanced cell adhesion and proliferation. mAESO in the nanocomposites resulted in greater adhesion, proliferation, and activity at day 7 compared with AESO nanocomposites. Excellent osteoclast-like cells survival, defined actin rings, and large multinucleated cells were only observed on the high nHA fraction (30%) mAESO nanocomposite and the HA control. Thus, mAESO-based nanocomposites containing higher amounts of nHA have better interactions with osteoblast-like and osteoclast-like cells, comparable with HA controls, making them a potential future alternative graft material for bone defect repair.

Development of a 3D multifunctional collagen scaffold impregnated with peptide LL-37 for vascularised bone tissue regeneration

Bone is a highly dynamic connective tissue that provides structural support, locomotion and acts as a shield for many vital organs from damage. Bone inherits the ability to heal after non-severe injury. In case of severe bone abnormalities due to trauma, infections, genetic disorders and tumors, there is a demand for a scaffold that can enhance bone formation and regenerate the lost bone tissue. In this study, a 3D collagen scaffold (CS) was functionalized and assessed under in vitro and in vivo conditions. For this, a collagen scaffold coated with hydroxyapatite (Ap-CS) was developed and loaded with a peptide LL-37. The physico-chemical characterisation confirmed the hydroxyapatite coating on the outer and inner surfaces of Ap-CS. In vitro studies confirmed that LL-37 loaded Ap-CS promotes osteogenic differentiation of human osteosarcoma cells without showing significant cytotoxicity. The efficacy of the LL-37 loaded Ap-CS for bone regeneration was evaluated at 4 and 12 weeks post-implantation by histopathological and micro-CT analysis in rabbit femur defect model. The implanted LL-37 loaded Ap-CS facilitated the new bone formation at 4 weeks compared with Ap-CS without LL-37. The LL-37 loaded Ap-CS incorporating apatite and peptide LL-37 would be useful as a multifunctional scaffold for bone tissue engineering.

Chitin scaffolds derived from the marine demosponge Aplysina fistularis stimulate the differentiation of dental pulp stem cells

The use of stem cells for tissue regeneration is a prominent trend in regenerative medicine and tissue engineering. In particular, dental pulp stem cells (DPSCs) have garnered considerable attention. When exposed to specific conditions, DPSCs have the ability to differentiate into osteoblasts and odontoblasts. Scaffolds are critical for cell differentiation because they replicate the 3D microenvironment of the niche and enhance cell adhesion, migration, and differentiation. The purpose of this study is to present the biological responses of human DPSCs to a purified 3D chitin scaffold derived from the marine demosponge Aplysina fistularis and modified with hydroxyapatite (HAp). Responses examined included proliferation, adhesion, and differentiation. The control culture consisted of the human osteoblast cell line, hFOB 1.19. Electron microscopy was used to examine the ultrastructure of the cells (transmission electron microscopy) and the surface of the scaffold (scanning electron microscopy). Cell adhesion to the scaffolds was determined by neutral red and crystal violet staining methods. An alkaline phosphatase (ALP) assay was used for assessing osteoblast/odontoblast differentiation. We evaluated the expression of osteogenic marker genes by performing ddPCR for ALP, RUNX2, and SPP1 mRNA expression levels. The results show that the chitin biomaterial provides a favorable environment for DPSC and hFOB 1.19 cell adhesion and supports both cell proliferation and differentiation. The chitin scaffold, especially with HAp modification, isolated from A. fistularis can make a significant contribution to tissue engineering and regenerative medicine.

Tubular nanomaterials for bone tissue engineering

Nanomaterial composition, morphology, and mechanical performance are critical parameters for tissue engineering. Within this rapidly expanding space, tubular nanomaterials (TNs), including carbon nanotubes (CNTs), titanium oxide nanotubes (TNTs), halloysite nanotubes (HNTs), silica nanotubes (SiNTs), and hydroxyapatite nanotubes (HANTs) have shown significant potential across a broad range of applications due to their high surface area, versatile surface chemistry, well-defined mechanical properties, excellent biocompatibility, and monodispersity. These include drug delivery vectors, imaging contrast agents, and scaffolds for bone tissue engineering. This review is centered on the recent developments in TN-based biomaterials for structural tissue engineering, with a strong focus on bone tissue regeneration. It includes a detailed literature review on TN-based orthopedic coatings for metallic implants and composite scaffolds to enhance in vivo bone regeneration.

Current Development in Biomaterials-Hydroxyapatite and Bioglass for Applications in Biomedical Field: A Review

Inorganic biomaterials, including different types of metals and ceramics are widely used in various fields due to their biocompatibility, bioactivity, and bioresorbable capacity. In recent years, biomaterials have been used in biomedical and biological applications. Calcium phosphate (CaPs) compounds are gaining importance in the field of biomaterials used as a standalone material or in more complex structures, especially for bone substitutes and drug delivery systems. The use of multiple dopants into the structure of CaPs compounds can significantly improve their in vivo and in vitro activity. Among the general information included in the Introduction section, in the first section of this review paper, the authors provided a background on the development of hydroxyapatite, methods of synthesis, and its applications. The advantages of using different ions and co-ions for substitution into the hydroxyapatite lattice and their influence on physicochemical, antibacterial, and biological properties of hydroxyapatite are also presented in this section of the review paper. Larry Hench's 45S5 Bioglass®, commercially named 45S5, was the first bioactive glass that revealed a chemical bond with bone, highlighting the potential of this biomaterial to be widely used in biomedicine for bone regeneration. The second section of this article is focused on the development and current products based on 45S5 Bioglass®, covering the historical evolution, importance of the sintering method, hybrid bioglass composites, and applications. To overcome the limitations of the original biomaterials, studies were performed to combine hydroxyapatite and 45S5 Bioglass® into new composites used for their high bioactivity and improved properties. This particular type of combined hydroxyapatite/bioglass biomaterial is discussed in the last section of this review paper.

Strontium-incorporated bioceramic scaffolds for enhanced osteoporosis bone regeneration

The restoration of bone defects caused by osteoporosis remains a challenge for surgeons. Strontium ranelate has been applied in preventative treatment approaches due to the biological functions of the trace element strontium (Sr). In this study, we aimed to fabricate bioactive scaffolds through Sr incorporation based on our previously developed modified amino-functional mesoporous bioactive glass (MBG) and to systematically investigate the bioactivity of the resulting scaffold in vitro and in vivo in an osteoporotic rat model. The results suggested that Sr-incorporated amino-functional MBG scaffolds possessed favorable biocompatibility. Moreover, with the incorporation of Sr, osteogenic and angiogenic capacities were upregulated in vitro. The in vivo results showed that the Sr-incorporated amino-functional MBG scaffolds achieved better bone regeneration and vessel formation. Furthermore, bioinformatics analysis indicated that the Sr-incorporated amino-functional MBG scaffolds could reduce reactive oxygen species levels in bone marrow mesenchymal stem cells in the osteoporotic model by activating the cAMP/PKA signaling pathway, thus playing an anti-osteoporosis role while promoting osteogenesis. This study demonstrated the feasibility of incorporating trace elements into scaffolds and provided new insights into biomaterial design for facilitating bone regeneration in the treatment of osteoporosis.

Investigations on the Influence of Collagen Type on Physicochemical Properties of PVP/PVA Composites Enriched with Hydroxyapatite Developed for Biomedical Applications

Nowadays, a great attention is directed into development of innovative multifunctional composites which may support bone tissue regeneration. This may be achieved by combining collagen and hydroxyapatite showing bioactivity, osteoconductivity and osteoinductivity with such biocompatible polymers as polyvinylpyrrolidone (PVP) and poly(vinyl alcohol) (PVA). Here PVA/PVP-based composites modified with hydroxyapatite (HAp, 10 wt.%) and collagen (30 wt.%) were obtained via UV radiation while two types of collagen were used (fish and bovine) and crosslinking agents differing in the average molecular weight. Next, their chemical structure was characterized using Fourier transform infrared (FT-IR) spectroscopy, roughness of their surfaces was determined using a stylus contact profilometer while their wettability was evaluated by a sessile drop method followed by the measurements of their surface free energy. Subsequently, swelling properties of composites were verified in simulated physiological liquids as well as the behavior of composites in these liquids by pH measurements. It was proved that collagen-modified composites showed higher swelling ability (even 25% more) compared to unmodified ones, surface roughness, biocompatibility towards simulated physiological liquids and hydrophilicity (contact angles lower than 90°). Considering physicochemical properties of developed materials and a possibility of the preparation of their various shapes and sizes, it may be concluded that developed materials showed great application potential for biomedical use, e.g., as materials filling bone defects supporting their treatments and promoting bone tissue regeneration due to the presence of hydroxyapatite with osteoinductive and osteoconductive properties.

Recycled Porcine Bone Powder as Filler in Thermoplastic Composite Materials Enriched with Chitosan for a Bone Scaffold Application

This work aims to synthesize biocompatible composite materials loaded with recycled porcine bone powder (BP) to fabricate scaffolds for in-situ reconstruction of bone structures. Polylactic acid (PLA) and poly(ε-caprolactone) (PCL) were tested as matrices in percentages from 40 wt% to 80 wt%. Chitosan (CS) was selected for its antibacterial properties, in the amount from 5 wt% to 15 wt%, and BP from 20 wt% to 50 wt% as active filler to promote osseointegration. In this preliminary investigation, samples have been produced by solvent casting to introduce the highest possible percentage of fillers. PCL has been chosen as a matrix due to its greater ability to incorporate fillers, ensuring their adequate dispersion and lower working temperatures compared to PLA. Tensile tests demonstrated strength properties (6–10 MPa) suitable for hard tissue engineering applications. Based on the different findings (integration of PLA in the composite system, improvements in CS adhesion and mechanical properties), the authors supposed an optimization of the synthesis process, focused on the possible implementation of the electrospinning technique to develop PCL-BP composites reinforced with PLA-CS microfibers. Finally, biological tests were conducted to evaluate the antibacterial activity of CS, demonstrating the applicability of the materials for the biomedical field.

Ursolic Acid Loaded-Mesoporous Hydroxylapatite/ Chitosan Therapeutic Scaffolds Regulate Bone Regeneration Ability by Promoting the M2-Type Polarization of Macrophages

PURPOSE

Mesoporous hydroxylapatite (MHAP) might be important for bone regeneration, and ursolic acid (UA) has anti-inflammatory effects. Accordingly, we developed, for the first time, ursolic acid-loaded MHAP-chitosan (MHAP-CS-UA) scaffolds to treat bone defects.

METHODS

In vitro, we synthesize biomaterial scaffolds. By SEM, XRD, EDS and FTIR, we test the performance of the hybrid scaffolds. By drug release, flow cytometry, immunofluorescence, alizarin red staining, and Western blotting, we test the anti-inflammatory and osteo-inductive properties of scaffolds. In vivo, we verify osseointegration ability and bone regeneration.

RESULTS

The MHAP is a rod-shaped structure with a length of 100~300nm and a diameter of 40~60nm. The critical structure gives the micro-scaffold a property of control release due to the pore sizes of 1.6~4.3 nm in hydroxyapatite and the hydrogen bonding between the scaffolds and UA drugs. The released UA drugs could notably inhibit the polarization of macrophages to pro-inflammatory macrophages (M1 type) and promote the expression of osteogenic-related genes (COL1, ALP and OPG) and osteogenic-related proteins (BMP-2, RUNX2 and COL1).

CONCLUSION

The MHAP-CS-UA scaffolds have good anti-inflammatory, osseointegration, osteo-inductivity and bone regeneration. And they will be the novel and promising candidates to cure the bone disease.

In vitro and in vivo study on the osseointegration of magnesium and strontium ion with two different proportions of mineralized collagen and its mechanism

To explore the optimal combination of Mg²⁺, Sr²⁺ and mineralized collagen (nHAC) with two different proportions of hydroxyapatite (HA) and collagen (COL) on differentiation of MC3T3-E1 and the underlying mechanism, as well as achieve bone osseointegration. MC3T3-E1 cells were cultured in a complete medium with Mg²⁺ at the concentration of 0, 4, 8, 12, 16, 20 mmol/L, Sr²⁺ at the concentration of 0, 3, 6, 12 mmol/L, and the impregnation solution of 3:7 and 5:5nHAC. The differentiation of MC3T3-E1 was measured by expression of osteogenic genes and proteins including Runx-2, BMP-2 and OCN and determined the activation of PI3K/AKT/GSK3β/β-catenin signaling pathway in 12 mmol/LMg²⁺+3 mmol/LSr²⁺+3:7nHAC group. Osteoporosis was induced in 18 female rats by means of ovariectomy, the implants were immersed in 60 mmol/LMg²⁺+15 mmol/LSr²⁺+3:7nHAC impregnation solution and implanted into the mesial alveolar fossa for immediate implantation. The osseointegration of the implants was observed by Confocal laser scanning microscopy (CLSM) and histology at 4 and 8 weeks. The groups cultured with 12 mmol/LMg²⁺, 3 mmol/LSr²⁺ and 3:7nHAC impregnation solution showed the osteogenic genes and proteins were significantly higher respectively (P < 0.05), as well as p-Akt, p-GSK3β and β-catenin proteins (P < 0.05). CLSM and histology showed that the implant surface was surrounded by thick lamellar bone plate, and the trabecular bone were dense and continuous in the impregnation solution. These results found that magnesium and strontium ion-loaded mineralized collagen play an critical role in up-regulating the cells activity through PI3K/AKT/GSK3β/β-catenin signaling pathway and could be promote the formation of osseointegration.