Chitosan/gelatin/platelet gel enriched by a combination of hydroxyapatite and beta-tricalcium phosphate in healing of a radial bone defect model in rat

Enhanced bone regeneration by low-intensity pulsed ultrasound and lipid microbubbles on PLGA/TCP 3D-printed scaffolds

BACKGROUND

To investigate the effect of low-intensity pulsed ultrasound (LIPUS) combined with lipid microbubbles on the proliferation and bone regeneration of bone marrow mesenchymal stem cells (BMSCs) in poly (lactic-glycolic acid copolymer) (PLGA)/α-tricalcium phosphate (TCP) 3D-printed scaffolds.

METHODS

BMSCs were irradiated with different LIPUS parameters and microbubble concentrations, and the best acoustic excitation parameters were selected. The expression of type I collagen and the activity of alkaline phosphatase were detected. Alizarin red staining was used to evaluate the calcium salt production during osteogenic differentiation.

RESULTS

BMSCs proliferation was the most significant under the condition of 0.5% (v/v) lipid microbubble concentration, 2.0 MHz frequency, 0.3 W/cm² sound intensity and 20% duty cycle. After 14 days, the type I collagen expression and alkaline phosphatase activity in the scaffold increased significantly compared to those in the control group, and alizarin red staining showed more calcium salt production during osteogenic differentiation. After 21 days, scanning electron microscopy experiments showed that osteogenesis was obvious in the PLGA/TCP scaffolds.

CONCLUSION

LIPUS combined with lipid microbubbles on PLGA/TCP scaffolds can promote BMSCs growth and bone differentiation, which is expected to provide a new and effective method for the treatment of bone regeneration in tissue engineering.

Bioactive impact of manuka honey and bone char incorporated into gelatin and chitosan cryogels in a rat calvarial fracture model

Bone tissue engineered scaffolds are designed to mimic the natural environment for regeneration when typical healing is inhibited. Autografts are the current gold standard for treatment but are limited by available bone and supplementary surgical sites that broaden complications and comorbidities. Cryogels are an ideal scaffold in bone regeneration due to their mechanical integrity and marcoporous structure that elicits angiogenesis and subsequently new bone tissue formation. To aid in bioactivity and osteoinductivity, manuka honey (MH) and bone char (BC) were added to gelatin and chitosan cryogels (CG). Manuka honey has powerful antimicrobial properties to aid against graft infection, and bone char is composed of 90% hydroxyapatite, a well-studied bioactive material. These additives are natural, abundant, easy to use, and cost effective. CG cryogels incorporated with either BC or MH, and plain CG cryogels were implanted into rat calvarial fracture models for cortical bone regeneration analysis. We found indication of bioactivity with both bone char and manuka honey through the presence of woven bone structure in histology stains and micro computed tomography (microCT) data. Overall, plain CG cryogels supported greater bone regeneration capabilities than the BC or MH incorporated cryogels due to a lack of advanced organized tissue formation and collagen deposition after 8 weeks of implantation; however, future work should explore varying additive concentrations and delivery methods to further assess additive potential.

A novel gelatin/carboxymethyl chitosan/nano-hydroxyapatite/β-tricalcium phosphate biomimetic nanocomposite scaffold for bone tissue engineering applications

Hydroxyapatite (HA) and tricalcium phosphate (TCP) constitute 60% of the content of the bone, and their combination has a better effect on bone tissue engineering than either single element. This study demonstrates a new degradable gelatin/carboxymethyl chitosan (CMC) bone scaffold loaded with both nano-HA and β-TCP (hereinafter referred to as HCP), and freeze drying combined with stir foaming was used to obtain highly connected macropores. Only a few studies have used these components to synthesize a four-component osteogenic scaffold. The aim of this study was to comprehensively assess the biocompatibility and osteoinductivity of the nanocomposites. Three HCP/CMC/gelatin scaffolds were made with different HCP contents: group A (10 wt% HCP), group B (30 wt% HCP), and group C (50 wt% HCP) (the ratio of nano-HA and β-TCP was fixed at 3:2). The scaffolds were macroporous with a high porosity and pore connectivity, as observed by morphological analysis by scanning electron microscopy. Additionally, the pore size of groups A and B was more homogeneous than that of group C. There were no significant differences in physicochemical characterization among the three groups. The Fourier-transform infrared (FTIR) spectroscopy test indicated that the scaffold contained active groups, such as hydroxyl, amino, or peptide bonds, corresponding to gelatin and CMC. The XRD results showed that the phase structures of HA and β-TCP did not change in the nanocomposite. The scaffolds had biodegradation potential and an appreciable swelling ratio, as demonstrated with the in vitro test. The scaffolds were cultured in vitro with MC3T3-E1 cells, showing that osteoinduction and osteoconduction increased with the HCP content. None of the scaffolds showed cytotoxicity. However, cell adhesion and growth in group B were better than those in group A and group C. Therefore, freeze drying combined with a stir foaming method may have a solid component limit. This study demonstrates a novel four-component scaffold via a simple manufacturing process. Group B (30% HCP) had the best characteristics for bone scaffold materials.

A review on bioceramics scaffolds for bone defect in different types of animal models: HA and β -TCP

Increased life expectancy has led to an increase in the use of bone substitutes in numerous nations, with over two million bone-grafting surgeries performed worldwide each year. A bone defect can be caused by trauma, infections, and tissue resections which can self-heal due to the osteoconductive nature of the native extracellular matrix components. However, natural self-healing is time-consuming, and new bone regeneration is slow, especially for large bone defects. It also remains a clinical challenge for surgeons to have a suitable bone substitute. To date, there are numerous potential treatments for bone grafting, including gold-standard autografts, allograft implantation, xenografts, or bone graft substitutes. Tricalcium phosphate (TCP) and hydroxyapatite (HA) are the most extensively used and studied bone substitutes due to their similar chemical composition to bone. The scaffolds should be testedin vivoandin vitrousing suitable animal models to ensure that the biomaterials work effectively as implants. Hence, this article aims to familiarize readers with the most frequently used animal models for biomaterials testing and highlight the available literature for in vivo studies using small and large animal models. This review summarizes the bio ceramic materials, particularly HA and β-TCP scaffolds, for bone defects in small and large animal models. Besides, the design considerations for the pre-clinical animal model selection for bone defect implants are emphasized and presented.

Application Progress of Modified Chitosan and Its Composite Biomaterials for Bone Tissue Engineering

In recent years, bone tissue engineering (BTE), as a multidisciplinary field, has shown considerable promise in replacing traditional treatment modalities (i.e., autografts, allografts, and xenografts). Since bone is such a complex and dynamic structure, the construction of bone tissue composite materials has become an attractive strategy to guide bone growth and regeneration. Chitosan and its derivatives have been promising vehicles for BTE owing to their unique physical and chemical properties. With intrinsic physicochemical characteristics and closeness to the extracellular matrix of bones, chitosan-based composite scaffolds have been proved to be a promising candidate for providing successful bone regeneration and defect repair capacity. Advances in chitosan-based scaffolds for BTE have produced efficient and efficacious bio-properties via material structural design and different modifications. Efforts have been put into the modification of chitosan to overcome its limitations, including insolubility in water, faster depolymerization in the body, and blood incompatibility. Herein, we discuss the various modification methods of chitosan that expand its fields of application, which would pave the way for future applied research in biomedical innovation and regenerative medicine.

Strategy of Stem Cell Transplantation for Bone Regeneration with Functionalized Biomaterials and Vascularized Tissues in Immunocompetent Mice

The use of human bone marrow mesenchymal stem cells (hBMSCs) to regenerate and repair bone tissue defects is a complex research field of bone tissue engineering; nevertheless, it is a hot topic. One of the biggest problems is the limited survival and osteogenic capacity of the transplanted cells within the host tissue. Even for hBMSCs with their low immunogenicity, the body will still cause a local immune-inflammatory response directed against the allogeneic cells and thereby reduce the activity of the transplanted cells. Even in the case of successful transplantation, the lack of vascularization at the transplantation site makes it difficult for the transplanted cells to exchange nutrients and metabolic wastes that ultimately affects bone regeneration. In this study, we covalently modified alginate with RGD and QK peptides that were injected subcutaneously into immunocompetent mice. Histological analysis, as well as ELISA techniques, proved that this method is able to provide bioactive stem cell transplant beds containing functionalized biomaterials and vascularized surrounding tissues. Inflammation-related factors, such as IL-2, IL-6, TNF-α, and IFN-γ, around the cell graft beds decreased with time and were lowest at the second week. Then, the hBMSCs were injected into the cell transplantation beds intended to form vascularized bonelike tissues that were evaluated by micro-computed tomography (Micro CT), histological, and immunohistochemical analyses. The results showed that the expression of osteogenesis-related proteins RUNX2, COL1A1, and OPN, as well as the expression of angiogenic factor vWF and cartilage-related protein COL2A1 were significantly upregulated in the hBMSC-derived osteogenic tissue. These results suggest that the stem cell transplantation strategy by constructing bioactive cell transplant beds is effective to enhance the bone regeneration capacity of hBMSCs and holds great potential in bone tissue engineering.

Composite Hydrogels of Alkyl Functionalized Gellan Gum Derivative and Hydroxyapatite/Tricalcium Phosphate Nanoparticles as Injectable Scaffolds for bone Regeneration

An alkyl functionalized gellan gum derivative is here used to produce hydrogels containing hydroxyapatite and tricalcium phosphate nanoparticles as injectable nanostructured scaffolds for bone regeneration. The amphiphilic nature of the polysaccharide derivative along with its thermotropic behavior and ionotropic crosslinking features make possible to produce injectable bone mimetic scaffolds that can be used to release viable cells and osteoinductive biomolecules. The influence of different nanoparticles concentration on the rheological and physicochemical properties of the injectable systems is studied. It is found that the presence of inorganic nanoparticles reinforces the 3D hydrated polymeric networks without influencing their injectability but improving the physicochemical properties of ionotropic crosslinked hydrogels produced with two different curing media. Preliminary cytocompatibility tests performed with murine preosteoblast cells revealed that gellan gum based hydrogels can safely encapsulate viable cells. Loading and release experiments for dexamethasone and stromal cell-derived factor-1 demonstrate the drug delivery features of the obtained injectable systems.

Effects of Combination of BMP7, PFG, and Autograft on Healing of the Experimental Critical Radial Bone Defect by Induced Membrane (Masquelet) Technique in Rabbit

Background

Healing of large segmental bone defects can be challenging for orthopedic surgeons. This research was conducted to provide further insight into the effects of BMP7 in combination with autograft and platelet fibrin glue (PFG) on bone regeneration by Masquelet technique (MT).

Methods

Twenty five domestic male rabbits, more than 6 months old, weighing 2.00±0.25 kg were randomly divided into five equal groups as follows: MT-blank cavity (without any biological or synthetic materials) (1), blank cavity (2), MT-autograft (3), MT-autograft-BMP7 (4), and MT-BMP7-PFG (5). A 20 mm segmental defect was made in radial bone in both forelimbs. The Masquelet technique was done in all groups except group 2. The study was evaluated by radiology, biomechanics, histopathology and scanning electron microscopy.

Results

The results showed that Masquelet technique enhanced the healing process, as, the structural and functional criteria of the injured bone showed significantly improved bone healing (P<0.05). Treatment by PFG-BMP7, Autograft-BMP7, and autograft demonstrated beneficial effects on bone healing. However, Autograft-BMP7 was more effective than autograft in healing of the radial defect in rabbits.

Conclusion

Our findings introduce the osteogenic materials in combination with Masquelet technique as an alternative for reconstruction of the big diaphyseal defects in the long bones in animal models. Our findings may be useful for clinical application in future.

Current applications of platelet gels in wound healing-A review

Human platelets play important roles in several physiologic and pathologic processes. Platelet concentrates are activated with thrombin or calcium, resulting in a viscous coagulum (platelet gel [PG]), composed of 95% platelets at least. PG is increasingly used for the treatment of a variety of soft and hard tissue defects, most notably in the management of chronic non-healing wounds. During wound healing, platelets not only play a critical role in primary hemostasis and thrombosis, but also release growth factors and cytokines to promote tissue regeneration, enhance collagen synthesis, and trigger an immune response. This review addresses a variety of aspects relevant to the functions of well-known platelet growth factors, animal and clinical studies of PG in the last decade, and different sources of platelets for PG. PG is used for non-healing chronic wounds, such as oral ulcerations related to epidermolysis bullosa and chronic graft-versus-host disease, for those, the traditional treatment effect is poor. PG maybe provide a new therapeutic direction for these diseases. Nevertheless, some uncertainty is present, the number of clinical studies is not enough. Hence, randomized controlled trials are still required to study the potential of the use of PG in the near future.

Role of bone 1stem cell-seeded 3D polylactic acid/polycaprolactone/hydroxyapatite scaffold on a critical-sized radial bone defect in rat

Osteoconductive biomaterials were used to find the most reliable materials in bone healing. Our focus was on the bone healing capacity of the stem cell-loaded and unloaded PLA/PCL/HA scaffolds. The 3D scaffold of PLA/PCL/HA was characterized by scanning electron microscopy (SEM), rheology, X-ray diffraction (XRD), and Fourier transform-infrared (FT-IR) spectroscopy. Bone marrow stem cells (BMSCs) have multipotential differentiation into osteoblasts. Forty Wistar male rats were used to organize four experimental groups: control, autograft, scaffold, and BMSCs-loaded scaffold groups. qRT-PCR showed that the BMSCs-loaded scaffold had a higher expression level of CD31 and osteogenic markers compared with the control group (P < 0.05). Radiology and computed tomography (CT) scan evaluations showed significant improvement in the BMSCs-loaded scaffold compared with the control group (P < 0.001). Biomechanical estimation demonstrated significantly higher stress (P < 0.01), stiffness (P < 0.001), and ultimate load (P < 0.01) in the autograft and BMSCs-loaded scaffold groups compared with the untreated group and higher strain was seen in the control group than the other groups (P < 0.01). Histomorphometric and immunohistochemical (IHC) investigations showed significantly improved regeneration scores in the autograft and BMSCs-loaded scaffold groups compared with the control group (P < 0.05). Also, there was a significant difference between the scaffold and control groups in all tests (P < 0.05). The results depicted that our novel approach will allow to develop PLA/PCL/HA 3D scaffold in bone healing via BMSC loading.

Effectiveness of a biodegradable 3D polylactic acid/poly(ɛ-caprolactone)/hydroxyapatite scaffold loaded by differentiated osteogenic cells in a critical-sized radius bone defect in rat

The effects of a scaffold made of polylactic acid, poly (ɛ-caprolactone) and hydroxyapatite by indirect 3D printing method with and without differentiated bone cells was tested on the regeneration of a critical radial bone defect in rat. The scaffold characterization and mechanical performance were determined by the rheology, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectrometry. The defects were created in forty Wistar rats which were randomly divided into the untreated, autograft, scaffold cell-free, and differentiated bone cell-seeded scaffold groups (n = 10 in each group). The expression level of angiogenic and osteogenic markers, analyzed by quantitative real time-polymerase chain reaction (in vitro), significantly improved (p < 0.05) in the scaffold group compared to the untreated one. Radiology and computed tomography scan demonstrated a significant improvement in the cell-seeded scaffold group compared to the untreated one (p < 0.001). Biomechanical, histopathological, histomorphometric, and immunohistochemical investigations showed significantly better regeneration scores in the cell-seeded scaffold and autograft groups compared to the untreated group (p < 0.05). The cell-seeded scaffold and autograft groups did show comparable results on the 80^th day post-treatment (p > 0.05), however, most results in the scaffold group were significantly higher than the untreated group (p < 0.05). Differentiated bone cells can enhance bone regeneration potential of the scaffold.

Effectiveness of mesenchymal stem cell-seeded onto the 3D polylactic acid/polycaprolactone/hydroxyapatite scaffold on the radius bone defect in rat

PURPOSE

The importance of regeneration in large bone defects forces the orthopedic surgeons to search for a proper methodology. The present experiment evaluated the capability of polylactic acid/polycaprolactone/hydroxyapatite (PLA/PCL/HA) scaffold loaded with and without mesenchymal stem cells (MSCs) on bone regeneration.

METHODS

Fourier transform infrared spectrometry, X-ray diffraction, scanning electron microscopy, and rheology methodologies were used to characterize the scaffold. Forty Wistar rats were randomly divided into the four groups including the untreated defects as the control group and three other groups in which the bone defects were treated with autologous bones (autograft group), the PLA/PCL/HA scaffolds (PLA/PCL/HA group), and the MSCs-seeded scaffolds (MSCs-seeded PLA/PCL/HA group).

RESULTS

Based on the qRT-PCR results, significantly higher expression levels of osteocalcin, osteopontin, and CD31 were seen in the cell-seeded scaffold group compared to the control group (P < 0.05). The CT scanning and radiographic images depicted significantly more newly formed bonny tissue in the MSCs-loaded scaffold and autograft groups than the untreated group (P < 0.001). The immunohistochemistry, biomechanical, histopathologic, and histomorphometric evaluations demonstrated significantly improved regeneration in the autograft and MSCs-loaded scaffold groups compared to the non-treated group (P < 0.05). There were significant differences between the scaffold and untreated groups in all in vivo evaluations (P < 0.05).

CONCLUSION

The MSCs enhanced bone healing potential of the PLA/PCL/HA scaffold and the MSCs-seeded scaffold was comparable to the autograft as the golden treatment regimen (P > 0.05).

Imaging of nano-hydroxyapatite/chitosan scaffolds using a cone beam computed tomography device on rat calvarial defects with histological verification

OBJECTIVES

Τhis study aims at determining the ability of cone beam computed tomography (CBCT) to visualize critical-size defects (CSD) created at rat calvaria and filled with 75/25 w/w nano-hydroxyapatite/chitosan (nHAp/CS) scaffolds, prior to their histological investigation.

MATERIALS AND METHODS

Thirty adult Sprague Dawley rats, 15 males and 15 females, were used. Two CSD, 5 mm in diameter, were bilaterally trephined in the parietal bone. The right CSD was filled with nHAp/CS scaffold, while the left CSD remained empty, as the control group. Two female rats died post-operatively. Rats were euthanized at 2, 4, and 8 weeks post-surgery. Twenty-eight specimens (15 × 2 × 10 mm) were resected-containing both CSDs-and then scanned using a NewTom VGi CBCT imaging unit (Verona, Italy). The manufacturer's software trace region profile tool (NNT v6.2, Verona, Italy) was used in selected axial slices. The greyscale value (in ^VGiHU) and the traced/selected region of interest (ROI, in mm²) of those areas were automatically calculated. Subsequently, all specimens were histologically examined.

RESULTS

An increased ^VGiHU (P = 0.000), was observed in the experimental group relative to the control group. The ROI of CSD (in mm²) was significantly reduced (P = 0.001) from the fourth to the eighth week in both groups. No statistically significant difference between male and female rats (P = 0.188) was observed with respect to ^VGiHU.

CONCLUSIONS

The nHAp/CS scaffolds are easily visualized using a particular high-resolution CBCT device.

CLINICAL RELEVANCE

Both the CBCT measurements and also the histological results suggest that the nHAp/CS scaffold presence contributes to new bone formation in rat calvarial CSD.

Chitin/Chitosan: Versatile Ecological, Industrial, and Biomedical Applications

Chitin is a linear polysaccharide of N-acetylglucosamine, which is highly abundant in nature and mainly produced by marine crustaceans. Chitosan is obtained by hydrolytic deacetylation. Both polysaccharides are renewable resources, simply and cost-effectively extracted from waste material of fish industry, mainly crab and shrimp shells. Research over the past five decades has revealed that chitosan, in particular, possesses unique and useful characteristics such as chemical versatility, polyelectrolyte properties, gel- and film-forming ability, high adsorption capacity, antimicrobial and antioxidative properties, low toxicity, and biocompatibility and biodegradability features. A plethora of chemical chitosan derivatives have been synthesized yielding improved materials with suggested or effective applications in water treatment, biosensor engineering, agriculture, food processing and storage, textile additives, cosmetics fabrication, and in veterinary and human medicine. The number of studies in this research field has exploded particularly during the last two decades. Here, we review recent advances in utilizing chitosan and chitosan derivatives in different technical, agricultural, and biomedical fields.

Three-dimensional (3D) printed scaffold and material selection for bone repair

Critical-sized bone defect repair remains a substantial challenge in clinical settings and requires bone grafts or bone substitute materials. However, existing biomaterials often do not meet the clinical requirements of structural support, osteoinductive property, and controllable biodegradability. To treat large-scale bone defects, the development of three-dimensional (3D) porous scaffolds has received considerable focus within bone engineering. A variety of biomaterials and manufacturing methods, including 3D printing, have emerged to fabricate patient-specific bioactive scaffolds that possess controlled micro-architectures for bridging bone defects in complex configurations. During the last decade, with the development of the 3D printing industry, a large number of tissue-engineered scaffolds have been created for preclinical and clinical applications using novel materials and innovative technologies. Thus, this review provides a brief overview of current progress in existing biomaterials and tissue engineering scaffolds prepared by 3D printing technologies, with an emphasis on the material selection, scaffold design optimization, and their preclinical and clinical applications in the repair of critical-sized bone defects. Furthermore, it will elaborate on the current limitations and potential future prospects of 3D printing technology. STATEMENT OF SIGNIFICANCE: 3D printing has emerged as a critical fabrication process for bone engineering due to its ability to control bulk geometry and internal structure of tissue scaffolds. The advancement of bioprinting methods and compatible ink materials for bone engineering have been a major focus to develop optimal 3D scaffolds for bone defect repair. Achieving a successful balance of cellular function, cellular viability, and mechanical integrity under load-bearing conditions is critical. Hybridization of natural and synthetic polymer-based materials is a promising approach to create novel tissue engineered scaffolds that combines the advantages of both materials and meets various requirements, including biological activity, mechanical strength, easy fabrication and controllable degradation. 3D printing is linked to the future of bone grafts to create on-demand patient-specific scaffolds.

Evaluation of the Possible Synergic Regenerative Effects of Platelet-Rich Plasma and Hydroxyapatite/Zirconia in the Rabbit Mandible Defect Model

BACKGROUND

Platelet-rich plasma (PRP) and bioceramics such as hydroxyapatite (HA) and zirconium oxide (ZrO₂) are used to reconstruct mandibular defects. We sought to determine the synergistic effects of HA/ZrO₂ and PRP and compare their osteogenic activity.

METHODS

ZrO₂ scaffolds were constructed by the slurry method and were then coated with HA and impregnated by PRP/heparan sulfate (HS). Bilateral mandibular defects were created in 26 male rabbits. In 20 rabbits, the left defects were treated with HA/ZrO₂/PRP (Group 1) and the corresponding right defects were filled with HA/ZrO₂ (Group 2). The 6 remaining models were treated with PRP gels at both sides (Group 3). The osteoconductivity of HA/ZrO₂/PRP was compared with that of HA/ZrO₂ or PRP by radiological and histological methods after the follow-up period, at weeks 2, 6 and 8. The statistical analyses were performed by ANOVA and LSD using SPSS, version 16.0, for Windows (P<0.05).

RESULTS

After 2 weeks, the percentage of the surface occupied by bone was significantly higher in the HA/ZrO₂/PRP-treated defects than in the PRP-treated defects (P=0.007). Osteoblast and osteocyte counts were higher significantly in the PRP-treated group (P=0.032); however, the cells had not started matrix formation on a large scale and just small islands of osteoid with trapped osteocytes were observed. In the long term, the regenerative potential of all the scaffolds was the same.

CONCLUSION

HA/ZrO₂ showed a superior osteoconductive capacity over PRP in the short term; however, they showed no long-term synergic effects.

Platelet-Rich Plasma, Hydroxyapatite, and Chitosan in the Bone and Cartilaginous Regeneration of Femoral Trochlea in Rabbits: Clinical, Radiographic, and Histomorphometric Evaluations

The aim of this study was to evaluate the trochlear bone and cartilaginous regeneration of rabbits using the association of PRP, chitosan, and hydroxyapatite. Hole was made in rabbit troches, one hole in each animal remained empty (group C), and one was filled by a combination of PRP, chitosan, and hydroxyapatite (group T). Clinical-orthopedic, radiographic, and histomorphometric evaluations were performed. Clinical-orthopedic evaluation showed lameness of two members of the T group and one member of group C. The radiographic evaluation showed that the T group showed absence of subchondral bone reaction (33%). The presence of moderate subchondral bone reaction was more frequently reported in group C with 67%. Microscopic evaluation revealed a presence of tissue neoformation, composed of connective tissue. Microscopic findings were similar in both groups, with a difference in the amount of neoformed tissue being perceptible, which was confirmed after the morphometric analysis, which revealed a significant difference in the quantity of newly formed tissue at the bone/cartilage/implant interface. The composite base of the association of chitosan, hydroxyapatite, and platelet-rich plasma favored bone and cartilage healing.

Propolis extract a new reinforcement material in improving bone healing: An in vivo study

BACKGROUND

Propolis is known for its antioxidant, immune response modulating, and wound healing effects. In the present study in order to determine the bone healing capacity of the propolis extract, a critical sized, nonunion, radial bone defect model was repaired in rat, using chitosan and demineralized bone matrix (DBM) scaffolds along with propolis extract.

MATERIALS AND METHODS

Seventy-two radial bone defects in 36 healthy male rats were randomly divided into 6 groups (n = 12/group). The groups included autograft, defect or untreated group, chitosan, DBM, chitosan and propolis (chitosan-propolis), and DBM and propolis (DBM-propolis). The bone repairing capability was characterized using radiography at 28th, 42nd and 56th postoperative days. Gross morphologic, histopathologic, histomorphometric and biomechanical examinations were performed following euthanasia at the 56th post-operative day.

RESULTS

The DBM-propolis group, showed better structural and biomechanical properties compared to the untreated, DBM, chitosan and chitosan-propolis groups. The defect site in the chitosan and untreated groups were mainly restored by fibrous connective tissue while the lesions in the autograft group were mostly filled by cartilage and a lesser amount of woven bone. The woven bone, and the hyaline cartilage were the main constituents of the newly formed tissues in the DBM-propolis group, at the 56th day after injury.

CONCLUSION

The results of this study showed that percutaneous injection of diluted aqueous propolis extract in the bone defect (25 mg/defect) can improve bone formation in the critical radial bone defect in rat. Since there was no significant difference between the autograft and DBM-propolis group, probably this therapeutic strategy has high potential in augmentation of autologous bone grafting.

Porous Particle-Reinforced Bioactive Gelatin Scaffold for Large Segmental Bone Defect Repairing

Large segmental bone defect repairing remains a big challenge in clinics, and synthetic bone grafts suitable for this purpose are still highly demanded. In this article, hydrophilic composite scaffolds (bioactive hollow particle (BHP)-gel scaffold) composed of bioactive hollow nanoparticles and cross-linked gelatin have been developed. The bioactive nanoparticles have a porous structure as well as high specific surface area; thus, they interact strongly with gelatin to overcome the swelling problem that a hydrophilic polymer scaffold will usually face. With this combination, these BHP-gel scaffolds showed porous structure and mechanical properties similar to those of the cancellous bone. They also showed excellent bioactivity and cell growth promotion performance in vitro. The best of them, namely, 10BHP-gel scaffold, was evaluated in vivo on a rat femur model, where it was found that the 5 mm segmental bone defect almost healed with new bone tissue formed in 12 weeks and the scaffold itself degraded at the same time. Thus, 10BHP-gel scaffold may become a potential bone graft for large segmental bone defect healing in the future.

Synergistic effect of strontium, bioactive glass and nano-hydroxyapatite promotes bone regeneration of critical-sized radial bone defects

Critical-sized bone defects constitute a major health issue in orthopedics and usually cause mal-unions due to an inadequate number of migrated progenitor cells into the defect site or their incomplete differentiation into osteogenic precursor cells. The current study aimed to develop an optimized osteoinductive and angiogenic scaffold by incorporation of strontium (Sr) and bioglass (BG) into gelatin/nano-hydroxyapatite (G/nHAp) seeded with bone marrow mesenchymal stem cells to enhance bone regeneration. The scaffolds were fabricated by a freeze-drying technique and characterized in terms of morphology, structure, porosity and degradation rate. The effect of fabricated scaffolds on cell viability, attachment and differentiation into osteoblastic lineages was evaluated under in vitro condition. Micro computed tomography scan, histological and histomorphometric analysis were performed after implantation of scaffolds into the radial bone defects in rat. RT-PCR analysis showed that G/nHAp/BG/Sr scaffold significantly increased the expression level of osteogenic and angiogenic markers in comparison to other groups (P < 0.05). Moreover, the defects treated with the BMSCs-seeded scaffolds showed superior bone formation and mechanical properties compared to the cell-free scaffolds 4 and 12 weeks post-implantation. Finally, the BMSCs-seeded G/nHAp/BG/Sr scaffold showed the greatest bone regenerative capacity which was more similar to autograft. It is concluded that combination of Sr, BG, and nHAp can synergistically enhance the bone regeneration process. In addition, our results demonstrated that the BMSCs have the potential to considerably increase the bone regeneration ability of osteoinductive scaffolds. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 107B: 50-64, 2019.