Healing Process Of Bone Defects Research Articles

VEGF as Alveolar Bone Regeneration Key Protein in SHED Secretome, Hydroxyapatite and Collagen Type 1 Scaffold: An In-Silico Study

Background: A combination of SHED secretome, hydroxyapatite, and collagen type 1 is a promising scaffold for the alveolar bone defect. IL10, VEGF, FGF2, and TGF-beta growth factors contained in SHED secretome can potentially increase bone regeneration, while HA and COL10A scaffolds bind bone tissue and stimulate osteoblasts in the bone formation process. However, the activity, interaction, and physicochemical factors of those growth factors need to be revealed to increase their potential in tissue engineering. Objective: This study aimed to decipher the molecular basis of SHED Secretome, hydroxyapatite, and collagen type 1 combination for identifying biomolecules that drive the alveolar bone regeneration process. Method: The Uniprot and PubChem databases collected protein and molecular data. Docking analysis using the STITCH and STRING webservers. Results: IL-10, VEGF, FGF-2, TGF-beta, COL10A1, and HA are known to be involved in the alveolar bone defect healing process. These proteins support each other's functions and are assumed to be essential in bone regeneration. The analysis results show that the VEGF protein has a high score of betweenness centrality and closeness centrality. This means that VEGF has the most frequent and efficient interactions with other proteins related to bone regeneration mechanisms. Meanwhile, the COL10A1 protein has the lowest score. It indicates the protein has low and limited interactions. Conclusion: The combination of SHED secretome and HA-collagen type I can potentially increase the bone regeneration process of the alveolar bone defect with VEGF as a critical protein because of its high interaction efficiency compared to other proteins.

Mg doped ZnO containing silk nanocomposite scaffolds for biofilm prevention during alveolar bone regeneration

Biofilms are created when micro-colonies adhere to a solid surface and produce a strong extracellular matrix which increases the risk of infection and impedes the healing process of bone defects. Although post-operative antibiotics are commonly prescribed to prevent infections, they carry the risk of side effects and antibiotic resistance. Current research explored the potential of magnesium doped zinc oxide incorporated silk fibroin scaffolds to prevent the biofilms formation for alveolar bone regeneration applications. Novel silk fibroin (SF)/hydroxyapatite (HA) scaffolds incorporated with magnesium-doped zinc oxide nanoparticles (Mg–ZnO NPs with 0.5, 1 and 2 % Mg) were fabricated by freeze gelation method. The data suggested that new materials exhibit remarkable antibacterial activity against Staphylococcus aureus. Moreover, these materials are also found to be both biodegradable and biocompatible. The study revealed that scaffolds displayed excellent antibacterial activity that was increased with increasing concentration of Mg in ZnO, with a maximum of 49.39 % was observed for 2 % of Mg doped ZnO. Additionally, biodegradation of the material also increases with the increase in concentration of Mg doping in ZnO. The adequate porosity in the range of 67 %–74.3 % was recorded of new materials substituted with Mg–ZnO, which led to improved cell viability (99.6 %) and uniform deposition of apatite over the surface of scaffolds, making it an excellent candidate for biomedical applications that require antibacterials properties with high cell viability.

Enhanced osteogenesis and physicochemical properties of PMMA bone cement with SrBG/HA porous core-shell microspheres

Artificial bone graft with osteoconductivity, angiogenesis, and immunomodulation is promising clinical therapeutics for the reluctant healing process of bone defects. Among various osteogenic substitutes, polymethyl methacrylate (PMMA) bone cement is a quit competitive platform due to its easy deployment to the bone defects with irregular shape and biomimetic mechanical properties. However, the biologically inert essence of PMMA is reliant on the passive osseointegration and cannot provide sufficient biologic cues to induce fast bone repair. Bioactive glass could serve as an efficient platform for the active osteogenesis of PMMA via ionic therapy and construction of alkaline microenvironment. However, the direct of deployment of bioactive glass into PMMA may trigger additional cytotoxicity and hinder cell growth on its surface. Hence we incorporated ionic therapy as osteogenic cue into the PMMA to enhance the biomedical properties. Specifically, we synthesized core-shell microspheres with a strontium-doped bioactive glass (SrBG) core and hydroxyapatite (HA) shell, and then composited them with PMMA to introduce multifunctional effects of HA incorporation, alkaline microenvironment construction, and functional ion release by adding microsphere. We prepared xSrBG@HA/PMMA cements (x = 30, 40, 50) with varied microsphere content and evaluated impacts on mechanical/handling properties, ion release, and investigated the impacts of different composite cements on proliferation, osteogenic differentiation, angiogenic potential, and macrophage polarization. These findings provide new perspectives and methodologies for developing advanced bone biomaterials to promote tissue regeneration.

A self-powered, implantable bone-electronic interface for home-based therapeutic strategy of bone regeneration

Bone traumatic injuries, enduring a prolonged healing process since it involves a series of bio events, becomes gradually challenging with increasing aging population. The integration of a home-based therapy strategy with emerging microelectronic technology holds promise for optimizing the whole long-term healing process of bone defect. Given the bioelectric properties of bone, utilizing biomedical electronics to providing external electric field (EF) is preferred for physical therapy strategies. Our study provides a wireless implantable bone-electronic interface (IBEI) based on ultrasonic-driven battery-free piezoelectric technology. The IBEI without percutaneous leads can effectively complete the process of converting ultrasonic signals into electric signals and finally into biological signals for bone repair. This system is miniatured, battery-free, wireless, controllable, biocomfortable and biosafe with high osteogenic efficiency. For the underlying mechanism, the EF can activate multicellular synergistic osteogenesis and up-regulate the Ca2+/CaMKIIα/CREB signal pathway in osteogenesis effector cells. The IBEI aligns with the future trajectory of home-based medicine, presenting a commendable therapy pattern for doctor-patient collaboration and offering a novel perspective in the realm of physical therapy.

Synergistic effect of hierarchical topographic structure on 3D-printed Titanium scaffold for enhanced coupling of osteogenesis and angiogenesis

The significance of the osteogenesis-angiogenesis relationship in the healing process of bone defects has been increasingly emphasized in recent academic research. Surface topography plays a crucial role in guiding cellular behaviors. Metal-organic framework (MOF) is an innovative biomaterial with nanoscale structural and topological features, enabling the modulation of scaffold physicochemical properties. This study involved the loading of varying quantities of UiO-66 nanocrystals onto alkali-heat treated 3D-printed titanium scaffolds, resulting in the formation of hierarchical micro/nano topography named UiO-66/AHTs. The physicochemical properties of these scaffolds were subsequently characterized. Furthermore, the impact of these scaffolds on the osteogenic potential of BMSCs, the angiogenic potential of HUVECs, and their intercellular communication were investigated. The findings of this study indicated that 1/2UiO-66/AHT outperformed other groups in terms of osteogenic and angiogenic induction, as well as in promoting intercellular crosstalk by enhancing paracrine effects. These results suggest a promising biomimetic hierarchical topography design that facilitates the coupling of osteogenesis and angiogenesis.

Effect of Eucommia Ulmoides on Healing of Bon Defect Using Histological and Histomorphometric Analysis in Rat: in vivo Study.

Bone repair is a complex multistep process. The flavonoid group present in Eucommia ulmoides (EU) helps to increase bone mineral density. This study aimed to evaluate the healing process of bone defects treated with EU and compare it to the control group using histological and histomorphometric tests. For this purpose, 24 albino rats were anesthetized and both of their femurs were prepared by drilling intra-bony defects (2 mm in diameter and 3 mm in depth). In each rat, the right bony defects were considered control, while the left bony defects were treated with EU. Moreover, scarification was done with 1-, 2-, and 4-week healing intervals (n=8). Histological and histomorphometric analysis of bone microarchitectures were performed for more evaluations and the bone cells were counted (osteoblast, osteocyte, and osteoclast) for comparison with the normal percentages. Moreover, trabecular number, trabecular area, and bone marrow area per mm2 were measured using the ImageJ software. The recorded histological data revealed the acceleration of bone healing in the EU group, compared to the control group. Highly significant differences were observed in the animals treated with EU, compared to the control group for almost all histomorphometric parameters investigated in this Study. In conclusion, EU can improve bone healing and increase osteogenic capacity in rats.

Histological evaluation of the effects of bone morphogenetic protein 9 and angiopoietin 1 on bone healing

ObjectivesBone healing remains a critical clinical orthopedic problem. Bone, which is a greatly vascularized tissue, depends on the tight temporal and spatial link between blood vessels and bone cells. Thus, angiogenesis is crucial for skeletal growth and bone fracture healing. The purpose of this study was to evaluate the efficacy of the local application of osteogenic and angiogenic factors such as bone morphogenetic protein 9 (BMP9) and angiopoietin 1 (Ang1), respectively, and their combination as an osteoinducer in the process of bone healing. MethodsForty-eight male albino rats, weighing 300–400 g and aged 6–8 months, were utilized in this study. The animals underwent surgery on the medial side of the tibia bone. In the control group, an absorbable hemostatic sponge was locally applied to the bone defect, while experimental groups were separated into three groups. In Group I, 1 mg BMP9 was locally applied, Group II was treated with 1 mg Ang1, and Group III was treated with local application of a combination (0.5 mg BMP9 and 0.5 mg Ang1). All experimental groups were fixed with an absorbable hemostatic sponge. The rats were sacrificed on days 14 and 28 after surgery. ResultsLocal application of BMP9 alone, Ang1 alone, and their combination to a tibia defect caused osteoid tissue formation and significantly increased the number of bone cells. A gradual decrease in the number of trabecular bone, an increase in trabecular area, and no significant difference in the bone marrow area were noted. ConclusionThe combination of BMP9 and Ang1 has therapeutic potential in promoting the healing process of bone defects. Osteogenesis and angiogenesis are regulated by BMP9 and Ang1. These factors act together to accelerate bone regeneration more efficiently than either factor alone.

Freeze-Casted Keratin Matrix as an Organic Binder to Integrate Hydroxyapatite and BMP2 for Enhanced Cranial Bone Regeneration.

An ideal bone regenerative scaffold is expected to possess architectural characteristics that mimic the bone tissue, osteoconductive properties, and osteoinductive functionality. Key challenges to creating a scaffold with these ideal characteristics simultaneously are the selection of appropriate processing methods and biocompatible materials. Herein, human hair keratin is proposed as an organic binder for the simultaneous incorporation of bone's major inorganic component, hydroxyapatite and bone's growth factor, recombinant human bone morphogenetic protein 2 (rhBMP2) to enable both osteoconductive and osteoinductive characteristics in the creation of bone scaffolds. Furthermore, a freeze-casting method is selected to fabricate this rhBMP2-incorporated keratin/hydroxyapatite (KHA) scaffold with aligned lamellar pores to guide and promote bone regeneration. The aligned KHA scaffolds display better mechanical properties, sustained rhBMP2 release, good cell compliance, and 3D cellular infiltration. Implantation of KHA scaffolds in vivo reveals that scaffolds with aligned pores effectively accelerate the healing process of bone defects compared to scaffolds with random pores. This work indicates the distinctive potential of freeze-casted rhBMP-2 incorporated KHA scaffolds for bone regeneration.

The development of novel multifunctional drug system 7,8-DHF@ZIF-8 and its potential application in bone defect healing

Physical exercise has long been considered an essential regulator of bone formation. Recent studies have shown that brain-derived neurotrophic factor (BDNF) is an important cytokine released during physical exercise to promote osteogenic differentiation and facilitate the bone defect healing process. In this study, we developed a multifunctional system 7,8-DHF@ZIF-8, which combines the superior osteogenesis and angiogenesis properties of ZIF-8 and the unique capability of 7,8-DHF to mimic the function of BDNF to compensate for the routine physical exercise missed during the bone defect period. Various material characterizations were performed to confirm the successful synthesis of 7,8-DHF@ZIF-8. Drug release experiments suggested that 7,8-DHF@ZIF-8 could achieve slow diffusive release under physiological conditions within seven days. In vitro cell experiments indicated that low concentrations of ZIF-8 and 7,8-DHF@ZIF-8 could significantly promote the proliferation of MC3T3-E1 cells. Moreover, as proved by RT-QPCR analysis, incorporating 7,8-DHF into ZIF-8 could further enhance osteogenesis and angiogenesis-related gene expression. Therefore, we believe that the multifunctional drug system 7,8-DHF@ZIF-8 should have promising applications to facilitate bone defect healing.

Ultrasonographic and Radiographic Evaluation of Zeolite/Collagen Nanocomposite Scaffolds Compared With Nanohydroxyapatite on Experimental Bone Defect Healing in Rabbit Femur

Objectives: The use of a biomaterial scaffold can improve the healing process of bone defects. Using radiologic and ultrasonographic methods, this study aimed to evaluate the effects of zeolite/collagen nanocomposite and nanohydroxyapatite (nHA) bone scaffolds on the healing process of bone defect in rabbit femur. Materials and Methods: Twenty-eight mature male New Zealand white rabbits were classified into four equal groups (n=7 in each). In the first group, the defect was made, and the wound was closed with no treatment; in the second group, the nHA was implanted into the defect; in the third group, the nanocomposite of zeolite/collagen was implanted; and in the fourth group, the defect was filled using autograft. Radiologic (Sedecal Veterinary X-Ray System, Model No. A6544-2) and ultrasonographic (Mindray Z5 Veterinary Ultrasound Scanner) examinations were done on days 0, 15, 30, 45, and 60 postoperatively. Results: There were no healing effects on days 0 and 7 in any of the studied groups in the radiologic examination. The highest and lowest healing effects were related to treatment with zeolite/collagen nanocomposite and control group on day 60 after operation, respectively. There was no angiogenesis on day 0 in any group in the ultrasonographic examination. The highest and lowest levels of angiogenesis were related to rabbits treated with zeolite/collagen nanocomposite and the control group on day 30 after operation, respectively. Also, bone filling and angiogenesis in rabbits treated with zeolite/collagen nanocomposite were higher than other groups. Conclusions: Zeolite/collagen nanocomposite scaffolds bear a crucial capability in the reconstruction of bone defects and can be used in bone fractures.

Bone tissue engineering application on fracture healing with bone defect as assessed through osteocalcin and bone morphogenetic protein-2 (BMP-2) biomarker examination: experimental study on murine models

Background: Bone is naturally regenerable, with a high ability to repair itself. In massive segmental bone defect, bone cannot be repaired independently. Therefore, it is necessary to give a bone graft to promote the healing process. To date, autografts are the gold standard for bone grafts. However, some of the reported complications reported have led to auto-bone transplants being often disregarded. Both autografts or allografts also have some issues. Therefore, in an effort to develop alternative treatments for correcting bone defects and their consequences, bone tissue engineering (BTE) has gained popularity and is nowadays being researched as a potential alternative in bone defect management. There are three fundamental components in BTE combined: biomaterials (scaffolds), mesenchymal stem cells (MSCs), and growth factors. The combination of these components is believed to help the healing process of bone defects. Methods: This work was an animal study involving twenty Wistar strain Rattus norvegicus. They were divided into five groups: negative group (normal rats), positive group (rats with the bone defect without intervention), K-P1 group (rats with bone defect given SVF and porous carbonated- hydroxyapatite (HA)application), K-P2 group (rats with bone defect given SVF and nanocrystalline-HA application) and K-P3 (rats with bone defect giving SVF a bovine-HA application). After 30 days, the rats were sacrificed, the biomarkers osteocalcin and BMP-2 were evaluated. Biomarkers were quantified using ELISA. Results: Both osteocalcin and BMP-2 biomarker expressions were higher in intervention group (with SVF and scaffolds application) compared to the positive group (with no SVF and scaffolds treatment). The combination of SVF and bovine HA was reported significantly to have the highest osteocalcin and BMP levels when compared with other groups Conclusions: A combined application of SVF and scaffolds could aid the healing process in murine models with bone defect, marked by increasing levels of osteocalcin and BMP-2.

The effect of bone graft substitute in healing fractures with bone defects through examination of alkaline phosphatase and radiology in the murine model (Rattus norvegicus) Wistar strain

Background: A significant bone defect is a condition wherein the bone cannot repair spontaneously. Therefore, replacing bone defects with bone substitution remains a reconstructive concern for orthopaedic surgeons. Bone Graft Substitution (BGS) are classified broadly, such as bone grafts (autograft, allograft, and xenograft) synthetic ceramics (hydroxyapatite, calcium sulphate). This study aims to determine the effect of various Bone Graft Substitute on the healing process of bone defects assessed based on the area of callus formation and levels of alkaline phosphatase (ALP). Methods: The study design was an in vivo laboratory experimental approach with a randomized post-test only control group design. The 20 experimental animals that matched the inclusion criteria were divided into five groups, in each one of control positive group, one of control negative group, and three of treatment group. The bone graft substitution used in this study is a synthetic ceramic, namely Synthetic HA-Ca10(PO4)6(OH)2 - BONGROS®, Bone Graft Substitution Nanocrystalline HA-CaSO4-PEROSSAL®, and also hydroxyapatite Bovine. After selecting rats, we performed osteotomy on the femur to the made bone defect. After 30 days, murine models were harvested. Then, we measure callus formation using radiological examination and ALP level serum Results: From Callus formation, Nanocrystalline HA-CaSO4 is the highest (86.54 ± 4.24604) compared with other groups and significantly (p:0.021) increase in callus formation than the other experimental groups. Then, from the ALP level, Bovine is the highest (9.287 ± 0.58586) but did not significantly compare with K-neg, and the second one is Nanocrystalline HA-CaSO4 higher than KP-1, and it has a significantly higher levels serum ALP rather than K-Neg. Conclusion: Bone Graft Substituted using Nanocrystalline HA-CaSO4 is a good material that can repair and increase callus formation in fracture model rats with bone defects.

The Effect of Different Surgical Instruments for Bone Regeneration under the Surgery of Bone Defect on Rat Calvaria

In this study, we compared the healing process of bone defects treated with a trephine bur with those treated with an ultrasonic knife using a critical-sized bone defect model on rat calvaria. Nine-millimeter critical-size bone defects were prepared using both instruments in the calvaria of adult Sprague-Dawley rats. One and four weeks after the osteotomy, we performed a histomorphometric analysis to evaluate bone regeneration around the cutting surface. Quantitative micro-computed tomography analyses of the bone volume in both groups suggested that ultrasonic knife surgery resulted in superior bone formation compared to that in trephine bur surgery. Furthermore, at the cutting surface, the ultrasonic knife treatment retained the alkaline phosphatase activity and new bone formation, which was identified using calcein staining, even one week after surgery. Considering the speed and volume of bone regeneration, the ultrasonic knife is likely to be the preferred over the trephine bur to perform osteotomies in implant surgery.

Effect of Stromal Vascular Fraction on Fracture Healing with Bone Defects by Examination of Bone Morphogenetic Protein-2 Biomarkers in Murine Model

BACKGROUND: Fractures and segmental bone defects are a significant cause of morbidity and a source of a high economic burden in healthcare. A severe bone defect (3 mm in murine model) is a devastating condition, which the bone cannot heal naturally despite surgical stabilization and usually requires further surgical intervention. The stromal vascular fraction (SVF) contains a heterogeneous collection of cells and several components, primarily: MSCs, HSCs, Treg cells, pericytic cells, AST cells, extracellular matrix, and complex microvascular beds (fibroblasts, white blood cells, dendritic cells, and intra-adventitial smooth muscular-like cells). Bone morphogenetic protein (BMP) is widely known for their important role in bone formation during mammalian development and confers a multifunctional role in the body, which has potential for therapeutic use. Studies have shown that BMPs play a role in the healing of large size bone defects. AIM: In this study, researchers aim to determine the effect of administering SVF from adipose tissue on the healing process of bone defects assessed based on the level biomarker of BMP-2. MATERIALS AND METHODS: This was an animal study involving 12 Wistar strain Rattus norvegivus. They were divided into three groups: Negative group (normal rats), positive group (rats with bone defect without SVF application), and SVF group (rats with bone defect with SVF application). After 30 days, the rats were sacrificed; the biomarkers that were evaluated are BMP-2. This biomarker was quantified using ELISA. RESULTS: BMP-2 biomarker expressions were higher in the SVF application group than in the group without SVF. All comparisons of the SVF group and positive control group showed significant differences (p = 0.026). CONCLUSION: SVF application could aid the healing process in a murine model with bone defect marked by the increased level of BMP-2 as a bone formation marker.

Transient activation of notch signaling enhances endogenous stromal cell expansion and subsequent bone defect repair.

BackgroundFollowing traumatic bone loss or removal of bone tumors, the failure of bone allograft transplantation for large bone defect repair remains a significant problem in orthopedics. Therefore, new strategies that can efficiently enhance allograft healing and long-term incorporation are critically needed.MethodIn this study, we first injected Notch-activating Jagged1 peptide to mice and then isolated bone marrow tissues and cells for proliferation and differentiation assays. Femur bone allograft surgery was also performed in Jagged1 pre-treated mice, and bone defect healing process were monitored by histology, Micro-CT and biomechanical testing.ResultOur results showed that Jagged1 therapeutic injection is sufficient to maximally activate Notch and promote bone marrow stromal cell proliferation in vivo, while no effects on bone structure were observed. More importantly, Jagged1 pre-treatment significantly promoted bone callus formation and increased bone mechanical strength during allograft healing in a femur bone defect mouse model.ConclusionThis study reveals that Notch in vivo activation can be induced by injection of Jagged1 peptide for expansion of local native stromal cells that will significantly enhance bone callus formation.The Translational potential of this ArticleThe clinical uses of this therapeutic strategy would be immediately applicable for chronic long bone defect repair. More importantly, this devised strategy for expansion of endogenous BMSCs can also be applied to enhance other tissue and organ repair.

Microfluidic 3D Printing Responsive Scaffolds with Biomimetic Enrichment Channels for Bone Regeneration

AbstractTissue‐engineered scaffolds have been extensively explored for treating bone defects; however, slow and insufficient vascularization throughout the scaffolds remains a key challenge for further application. Herein, a versatile microfluidic 3D printing strategy to fabricate black phosphorus (BP) incorporated fibrous scaffolds with photothermal responsive channels for improving vascularization and bone regeneration is proposed. The thermal channeled scaffolds display reversible shrinkage and swelling behavior controlled by near‐infrared irradiation, which facilitates the penetration of suspended cells into the scaffold channels and promotes the prevascularization. Furthermore, the embedded BP nanosheets exhibit intrinsic properties for in situ biomineralization and improve in vitro cell proliferation and osteogenic differentiation. Following transplantation in vivo, these channels also promote host vessel infiltration deep into the scaffolds and effectively accelerate the healing process of bone defects. Thus, it is believed that these near‐infrared responsive channeled scaffolds are promising candidates for tissue/vascular ingrowth in diverse tissue engineering applications.

PEGDA/HA mineralized hydrogel loaded with Exendin4 promotes bone regeneration in rat models with bone defects by inducing osteogenesis.

Scaffolds with osteogenic differentiation function play an important role in the healing process of bone defects. Here, we designed a high strength Poly(ethyleneglycol) diacrylate/Hydroxyapatite (PEGDA/HA) mineralized hydrogel loaded with Exendin4 for inducing osteogenic differentiation. In this study, PEGDA hydrogel was prepared by photo initiating method. PEGDA/HA mineralized hydrogel was prepared by in-situ precipitation method, and Exendin4 was loaded by gel adsorption. The effects of different calcium and phosphorus concentrations on the strength and Exendin4 release of PEGDA/HA hydrogels were investigated. Rat models of bone defect were made and randomly divided into 5 groups. The experimental group was implanted with PEGDA hydrogel, Exendin4-PEGDA hydrogel, PEGDA/HA mineralized hydrogel, Exendin4-PEGDA/HA mineralized hydrogel, and no materials were implanted in the blank control group. Computed tomography (CT) and histology were observed 4 and 8 weeks after operation. Our results revealed that the PEGDA/HA mineralized hydrogel had porous structure, high mechanical strength and good biocompatibility. In vitro release test showed that the mineralized hydrogel exhibited good sustained release profile within 20 d. The animal experiments showed that the mineralized hydrogel accelerated the formation of new bone after 4 and 8 weeks, and formed a seamless union on the defected bone area after 8 weeks. In conclusions, The Exendin4-PEGDA/HA mineralized hydrogel can effectively repair bone defects in rats, and it is expected to be used as a biomaterial for human bone tissue repair.

Segmental bone replacement via patient-specific, three-dimensional printed bioresorbable graft substitutes and their use as templates for the culture of mesenchymal stem cells under mechanical stimulation at various frequencies.

The treatment of large segmental bone defects remains a challenge as infection, delayed union, and nonunion are common postoperative complications. A three-dimensional printed bioresorbable and physiologically load-sustaining graft substitute was developed to mimic native bone tissue for segmental bone repair. Fabricated from polylactic acid, this graft substitute is novel as it is readily customizable to accommodate the particular size and location of the segmental bone of the patient to be replaced. Inspired by the structure of the native bone tissue, the graft substitute exhibits a gradient in porosity and pore size in the radial direction and exhibit mechanical properties similar to those of the native bone tissue. The graft substitute can serve as a template for tissue constructs via seeding with stem cells. The biocompatibility of such templates was tested under in vitro conditions using a dynamic culture of human mesenchymal stem cells. The effects of the mechanical loading of cell-seeded templates under in vitro conditions were assessed via subjecting the tissue constructs to 28 days of daily mechanical stimulation. The frequency of loading was found to have a significant effect on the rate of mineralization, as the alkaline phosphatase activity and calcium deposition were determined to be particularly high at the typical walking frequency of 2 Hz, suggesting that mechanical stimulation plays a significant role in facilitating the healing process of bone defects. Utilization of such patient-specific and biocompatible graft substitutes, coupled with patient's bone marrow cells seeded and exposed to mechanical stimulation of 2 Hz have the potential of reducing significant volumes of cadaveric tissue required, improving long-term graft stability and incorporation, and alleviating financial burdens associated with delayed or failed fusions of long bone defects.

237 - Bone healing of critical size calvarial defects in rabbits with collagen sponge reinforced poly glycolic acid

Objective: Nowadays composite scaffolds based on synthetic and natural biomaterials have attracted attention in healing of non-union bone fractures. We evaluated the capability of collagen/poly glycolic acid (PGA) scaffolds to regenerate bone in a critical-sized defect (CSD) rabbit calvarial. The bone defect healing process and inflammatory reactions were evaluated histologically, computed tomography (CT) scan and real time polymerase chain reaction (RT-PCR) (with bone specific primers: sialoprotein and alkaline phosphatase) at 4, 8 and 12 weeks postoperatively.

The effects of Anadara granosa shell-Stichopus hermanni on bFGF expressions and blood vessel counts in the bone defect healing process of Wistar rats

Background: Bone damage can be caused by various factors with treatment usually involving graft materials being applied to the defective area. Moreover, in the bone defect healing process, blood vessels are also considered to be an important energy source for cell proliferation. One of the angiogenic factors playing an important role in blood vessel formation is basic fibroblast growth factor (bFGF). Furthermore, synthesized hydroxyapatite derived from Anadara granosa (AG) shells constitutes one of the potential materials for use in bone graft. The gold sea cucumber genus Stichopus hermanni (SH) possesses the ability to stimulate endothelial progenitor cells inducing bFGF. Purpose: This study aims to investigate the effects of AG shells and SH on bFGF expressions and blood vessel counts within the bone healing process. Methods: Twenty four male Wistar rats were divided into three groups, namely: a control group (C), a treatment group was administered with blood cockle shell (AG), and a treatment group with blood cockle shell and golden sea cucumber (AG+SH). Defects were made on their femurs measuring half the diameter of a circular, no. 018. bur These rats were subsequently sacrificed on day 7 after surgery. The expressions of bFGF were measured by means of IHC technique, while the number of blood vessels was quantified using HE technique. The resulting data was subjected to statistical analysis using an Anova test followed by an LSD test (p < 0.05). Results: The one-way Anova test results combined with those of an LSD test showed there to be significant differences in bFGF expressions and blood vessel counts between the control group (K) and the treatment group (AG) as well as between the treatment group (AG) and the treatment group (AG+SH). Conclusions: A combination of Anadara granosa shell and Stichopus hermanni can increase the expression of bFGF and the number of blood vessels on day 7 during the bone healing process in Wistar rats.