Biphasic Calcium Phosphate Materials Research Articles

Biphasic bone substitutes coated with PLGA incorporating therapeutic ions Sr2+ and Mg2+: cytotoxicity cascade and in vivo response of immune and bone regeneration.

The incorporation of bioactive ions into biomaterials has gained significant attention as a strategy to enhance bone tissue regeneration on the molecular level. However, little knowledge exists about the effects of the addition of these ions on the immune response and especially on the most important cellular regulators, the macrophages. Thus, this study aimed to investigate the in vitro cytocompatibility and in vivo regulation of bone remodeling and material-related immune responses of a biphasic bone substitute (BBS) coated with metal ions (Sr2+/Mg2+) and PLGA, using the pure BBS as control group. Initially, two cytocompatible modified material variants were identified according to the in vitro results obtained following the DIN EN ISO 10993-5 protocol. The surface structure and ion release of both materials were characterized using SEM-EDX and ICP-OES. The materials were then implanted into Wistar rats for 10, 30, and 90days using a cranial defect model. Histopathological and histomorphometrical analyses were applied to evaluate material degradation, bone regeneration, osteoconductivity, and immune response. The findings revealed that in all study groups comparable new bone formation were found. However, during the early implantation period, the BBS_Sr2+ group exhibited significantly faster regeneration compared to the other two groups. Additionally, all materials induced comparable tissue and immune responses involving high numbers of both pro-inflammatory macrophages and multinucleated giant cells (MNGCs). In conclusion, this study delved into the repercussions of therapeutic ion doping on bone regeneration patterns and inflammatory responses, offering insights for the advancement of a new generation of biphasic calcium phosphate materials with potential clinical applicability.

Nanoscaled biphasic calcium phosphate modulates osteogenesis and attenuates LPS-induced inflammation

Micron-scale structure biphasic calcium phosphate (BCP) materials have demonstrated promising clinical outcomes in the field of bone tissue repair. However, research on biphasic calcium phosphate materials at the nanoscale level remains limited. In this study, we synthesize granular-shaped biphasic calcium phosphate nanomaterials with multiple desirable characteristics, including negatively charged surfaces, non-cytotoxicity, and the capability to penetrate cells, using a nanogrinding dispersion process with a polymeric carboxylic acid as the dispersant. Our results reveal that treating human osteoblasts with 0.5 μg/mL biphasic calcium phosphate nanomaterials results in a marked increase in alkaline phosphatase (ALP) activity and the upregulation of osteogenesis-related genes. Furthermore, these biphasic calcium phosphate nanomaterials exhibit immunomodulatory properties. Treatment of THP-1-derived macrophages with BCP nanomaterials decreases the expression of various inflammatory genes. Biphasic calcium phosphate nanomaterials also mitigate the elevated inflammatory gene expression and protein production triggered by lipopolysaccharide (LPS) exposure in THP-1-derived macrophages. Notably, we observe that biphasic calcium phosphate nanomaterials have the capacity to reverse the detrimental effects of LPS-stimulated macrophage-conditioned medium on osteoblastic activity and mineralization. These findings underscore the potential utility of biphasic calcium phosphate nanomaterials in clinical settings for the repair and regeneration of bone tissue. In conclusion, this study highlights the material properties and positive effects of biphasic calcium phosphate nanomaterials on osteogenesis and immune regulation, opening a promising avenue for further research on inflammatory osteolysis in patients undergoing clinical surgery.

Experimental study of a 3D-printing technique combined with biphasic calcium phosphates to treat osteonecrosis of the femoral head in a canine model

ObjectiveThis study was aimed to use a digital design of 3D-printing technology to create a surgical navigation template. At the same time, biphasic calcium phosphate (BCP) was applied to treat osteonecrosis of the femoral head (ONFH) in animal models, based on accurate positioning of necrotic lesions in the navigation templates and observation of its therapeutic effect.MethodsFifteen healthy adult male and female beagle dogs weighing 20 + 2 kg were randomly divided into three groups (n = 5) after establishing a model of ONFH using the liquid nitrogen freezing method. Each model underwent necrotic lesion creation and BPC implantations on one side of the femoral head and only necrotic lesion creation on the other side of the femoral head. Each group underwent CT examination, gross observation, histological examination and immunohistochemical staining at 6 weeks, 12 weeks and 18 weeks postoperatively.ResultsAt weeks 6, 12, and 18, CT and gross examination showed that the necrotic area in the experimental group was basically intact and had been completely raised by BCP material. In the control group, there were signs of bone repair in the femoral head, but there were still large bone defects and cavities. At week 18, extensive collapse of the cartilage surface was observed. Through histological examination, in the experimental group at 12 and 18 weeks, a large number of new and reconstructed bone trabeculae containing a large amount of collagen fibres were observed (P < 0.05), while in the control group, there was extensive necrosis of the bone trabeculae without cellular structural areas. Immunohistochemical examination observation: A large number of CD31-positive cells were observed in the experimental group at 6 weeks, gradually decreasing at 12 and 18 weeks (P < 0.05), while a small number of CD31-positive cells were observed in the control group at 18 weeks.ConclusionThe 3D-printed navigation template can accurately locate ONFH lesions. Implantation of BCP material can effectively play a supporting role, prevent the collapse of the loading surface, and induce bone formation and angiogenesis to some extent.

Sonochemical-synthesized biphasic tricalcium phosphate: Influence of synthesis parameters on the physicochemical properties and in vitro remineralization in artificial saliva

Biphasic calcium phosphate (BCP) is an ideal bone substitute with controllable bioresorption/biodegradation by changing its relative amount of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) compositions. This study investigated the effect of synthetic conditions on the physicochemical properties and the remineralization behaviors of BCP materials in artificial saliva (AS). BCPs were obtained under the sonochemical condition at pH of 5.0 (BCP_5), 7.0 (BCP_7), and 9.0 (BCP_9), and all were sintered at 800, 1000, and 1200 °C. The HA/β-TCP ratio of BCPs increased according to the pH increase during the synthesis process. BCP_5 sintered at 800 °C with the highest β-TCP contents demonstrated (1) fast neutralization capacity to prevent enamel from dissolving in acidic saliva and (2) remineralization ion supply, and (3) new apatite formation found in acidic AS, indicating its high potential remineralization agent for dental care applications.

Zn-doped Mono- and Biphasic Calcium Phosphate Materials Derived from Agriculture Waste and Their Potential Biomedical Applications: Part I.

In this study, calcium phosphate materials were obtained via a simple, eco-friendly wet synthesis method using hen eggshells as a calcium source. It was shown that Zn ions were successfully incorporated into hydroxyapatite (HA). The obtained ceramic composition depends on the zinc content. When doped with 10 mol % of Zn, in addition to HA and Zn-doped HA, DCPD (dicalcium phosphate dihydrate) appeared and its content increased with the increase in Zn concentration. All doped HA materials exhibited antimicrobial activity against S. aureus and E. coli. Nevertheless, fabricated samples significantly decreased preosteoblast (MC3T3-E1 Subclone 4) viability in vitro, exerting a cytotoxic effect which probably resulted from their high ionic reactivity.

HA/β-TCP Biphasic Calcium Phosphate Ceramics Derived From Butterfish Bones Loaded With Bone Marrow Mesenchymal Stem Cells Promote Osteogenesis

Biphasic calcium phosphate (BCP) containing hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) is considered the gold standard for bone repair. However, the complex synthesis of BCP restricts the wide application of BCP. In the preliminary work, we proved that the HA/β-TCP BCP ceramic material extracted from fishery waste had a good prospect as a bone replacement graft material for filling bone defects. This study aimed to explore the osteogenesis effect of BCP material derived from butterfish bones in vivo and in vitro. After loading human bone marrow mesenchymal stem cells (hBMSCs) with materials, we used scanning electron microscopy to observe cell adhesion and survival. Western blot analysis was used to detect osteogenic expression in vitro. Micro-computed tomography and hematoxylin–eosin staining were used to detect bone regeneration and material degradation rate in the rat femoral defect model. The results showed that hBMSCs grew well and adhered closely to the material. In vitro, the expression levels of bone formation–related markers ALP and Runx-2 of butterfish bones calcined at 900°C were generally higher than those in the other groups. Notably, in vivo, the osteogenesis ability of butterfish bones calcined at 900°C was almost comparable to that of the most commonly used Bio-Oss in clinical practice and was significantly better than that in the other groups. In summary, the BCP ceramic material derived from butterfish bones had good biocompatibility, osteoconductivity, and osteoinductivity, and had a good application prospect in the field of bone graft substitutes.

Tribo-mechanical measurements and in vivo performance of zirconia-containing biphasic calcium phosphate material implanted in a rat model for bone replacement applications

The present study aimed to optimize the mechanical and tribological performance of biphasic calcium phosphate (BCP) without sacrificing its excellent bioactivity and bioresorbability to be suitable for bone replacement applications. Zirconia (ZrO2) was added to BCP in various proportions to achieve this goal. Then resulting nanocomposites powders were sintered and characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Tri-bological measurements were determined for all samples prepared at different loads along with mechanical properties in terms of microhardness, compressive strength and elastic moduli group. Since the bioactivity of BCP could not be accurately evaluated in vitro, a selected nanocomposite was implanted in rats for 1, 2, 3 and 4 weeks. The obtained results showed that ZrO2 played a strong role in improving the tribo-mechanical properties of the prepared nanocomposites. It also reduced the particle sizes of the prepared powders from 64.5 to 43.4 nm. The implanted sample was completely covered and surrounded by fibrous connective tissue after two weeks, indicating the excellent bioactivity of this specimen. Based on these results, the prepared nanocomposites are suitable for bone replacement applications.

Synthesis and Characterization of Calcium Phosphate Materials Derived from Eggshells from Different Poultry with and without the Eggshell Membrane.

Calcium phosphate materials such as hydroxyapatite (HA) or tricalcium phosphate (β-TCP) are highly attractive due to their multitude of applications in bone replacement as well as their environmental and ecological credentials. In this research, quail, hen, duck, and pigeon eggshells were used as a calcium source to obtain calcium phosphate materials via the environmentally friendly wet synthesis. Using the eggshells with the organic membrane, the biphasic calcium phosphate materials composed mainly of HA were obtained. The second mineral phase was β-TCP in the case of using quail, hen, and pigeon eggshells and octacalcium phosphate (OCP) in the case of duck eggshells. The HA content in the obtained materials depended on the amount of membrane in the eggshells and decreased in the order of pigeon, duck, hen, and quail eggshells. The eggshell membrane removal from the eggshells caused the reduced content of HA and the presence of the more soluble β-TCP or OCP phase in the obtained materials. The calcium ions release profile in the PBS buffer indicates the potential biomedical application of these materials.

Preparation and characterization of porous HA/β-TCP biphasic calcium phosphate derived from butterfish bone

ABSTRACT HA/β-TCP biphasic calcium phosphate (BCP)ceramic materials have a wide application prospect in bone remodeling surgery as bone substitutes. This study extracted BCP from butterfish bone that was calcined at 700–1100 °C. Then, their composition and microstructure was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), inductively coupled plasma optical atom emissions spectroscopy (ICP-OES), scanning electron microscopy (SEM), and mercury intrusion porosimeter (MIP). The data showed that BCP containing hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) can be produced when the butterfish bone is calcined at >800 °C. The calcined butterfish bone contains a variety of trace metal elements. Taken together, the BCP material produced by calcination of butterfish bone above 800 °C shows a concentrated distribution of macropores and micropores, high porosity and nanograin size. Furthermore, it has a wide range of sources and is green and environmental-friendly, which is a potential source of BCP material.

A Review on Biphasic Calcium Phosphate Materials Derived from Fish Discards.

This review summarizes the results reported on the production of biphasic calcium phosphate (BCP) materials derived from fish wastes (i.e., heads, bones, skins, and viscera), known as fish discards, and offers an in-depth discussion on their promising potential for various applications in many fields, especially the biomedical one. Thus, considerable scientific and technological efforts were recently focused on the capability of these sustainable materials to be transformed into economically attractive and highly valuable by-products. As a consequence of using these wastes, plenty of beneficial social effects, with both economic and environmental impact, will arise. In the biomedical field, there is a strong and continuous interest for the development of innovative solutions for healthcare improvement using alternative materials of biogenic origin. Thus, the orthopedic field has witnessed a significant development due to an increased demand for a large variety of implants, grafts, and/or scaffolds. This is mainly due to the increase of life expectancy and higher frequency of bone-associated injuries and diseases. As a consequence, the domain of bone-tissue engineering has expanded to be able to address a plethora of bone-related traumas and to deliver a viable and efficient substitute to allografts or autografts by combining bioactive materials and cells for bone-tissue ingrowth. Among biomaterials, calcium phosphate (CaP)-based bio-ceramics are widely used in medicine, in particular in orthopedics and dentistry, due to their excellent bioactive, osteoconductive, and osteointegrative characteristics. Recently, BCP materials (synthetic or natural), a class of CaP, which consist of a mixture of two phases, hydroxyapatite (HA) and beta tricalcium phosphate (β-TCP), in different concentrations, gained increased attention due to their superior overall performances as compared to single-phase formulations. Moreover, the exploitation of BCP materials from by-products of fish industry was reported to be a safe, cheap, and simple procedure. In the dedicated literature, there are many reviews on synthetic HA, β-TCP, or BCP materials, but to the best of our knowledge, this is the first collection of results on the effects of processing conditions on the morphological, compositional, structural, mechanical, and biological properties of the fish discard-derived BCPs along with the tailoring of their features for various applications.

High throughput synthesis and screening of zinc-doped biphasic calcium phosphate for bone regeneration

Introducing high throughput experimental/screening method into the elements-doped calcium phosphate is expected to greatly increase the efficiency of finding out the most effective doping range. In this work, biphasic calcium phosphate (BCP) was used as the doping matrix and zinc was chosen as the doping element. The zinc-doped BCP with gradient doping content (0–10.0 mol.%) were synthesized by a high throughput chemical precipitation method. The effects of doping content on the phase, structure, morphology and cytological responses of zinc-doped BCP were investigated comparatively. The results showed that BCPs with similar composition while different zinc doping content were successfully prepared, and zinc tended to enter the β-TCP structure by substituting calcium at the Ca(5) and Ca(4) sites. The zinc concentration in powder extracts rose steadily with increasing the doping content of zinc. However, a burst release of zinc in the BCPs into the extracts appeared when the zinc doping content was higher than 6 mol.% and resulted in cell apoptosis. Zinc doping could effectively promote the osteogenic differentiation of bone marrow mesenchymal stem cells and regulated the expression of inflammatory and tissue healing related genes in macrophages for proper doping contents. The in vitro most effective zinc doping content range and doping content was 2.0–2.8 mol.% and 2.4 mol.%, respectively. Furthermore, the most effective zinc doping content was verified by the in vivo osteoinduction experiment conducted in beagle dorsal muscle. This work provides a reference for figuring out the effective doping content range of element in calcium phosphate and paves the way for developing a more bioactive BCP material for bone tissue engineering.

EIF2α-ATF4 Pathway Activated by a Change in the Calcium Environment Participates in BCP-Mediated Bone Regeneration.

Biphasic calcium phosphate (BCP) ceramic is a classic bone void filler and a common basis of new materials for bone defect repair. However, the specific mechanism of BCP in osteogenesis has not been fully elucidated. Endoplasmic reticulum stress (ERs) and the subsequent PERK-eIF2α-ATF4 pathway can be activated by various factors, including trauma and intracellular calcium changes, and therefore worth exploring as a potential mechanism in BCP-mediated bone repair. Herein, a rat lateral femoral epicondyle defect model in vivo and a simulated BCP-mediated calcium environment in vitro were constructed for the analysis of BCP-related osteogenesis and the activation of ERs and the eIF2α-ATF4 pathway. An inhibitor of eIF2α dephosphorylation (salubrinal) was also used to explore the effect of the eIF2α-ATF4 pathway on BCP-mediated bone regeneration. The results showed that the ERs and eIF2α-ATF4 pathway activation were observed during 4 weeks of bone repair, with a rapid but brief increase immediately after artificial defect surgery and a re-increase after 4 weeks with the resorption of BCP materials. Mild ERs and the activated eIF2α induced by the calcium changes mediated by BCP regulated the expression of osteogenic-related proteins and had an important role during the defect repair. In conclusion, the eIF2α-ATF4 pathway activated by a change in the calcium environment participates in BCP-mediated bone regeneration. eIF2α-ATF4 and ERs could provide new directions for further studies on new materials in bone tissue engineering.

Influence of different sintering temperatures on mesoporous structure and ectopic osteogenesis of biphasic calcium phosphate ceramic granule materials

To detect the difference in the osteogenesis ability of biphasic calcium phosphate (BCP) ceramic granular materials with different mesoporous diameters prepared at different sintering temperatures through in vivo and in vitro experiments, so as to provide evidence for screening BCP materials with better clinical application parameters. Three kinds of BCP (materials 1, 2, 3) were prepared by mixing hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) at a ratio of 8∶2 and sintered at 1 050, 1 150, and 1 250℃ for 3 hours, respectively. The internal porosity and the diameter, volume, and area of the mesopore were measured by Brunauer-Emmett-Teller test (BET); the composition of the material was evaluated by X-ray diffraction (XRD); the microscopic surface morphology of the material was observed by scanning electron microscopy (SEM). The 3rd generation bone marrow mesenchymal stem cells (BMSCs) from Sprague-Dawley rats were co-cultured with the materials 1, 2, and 3 for 7 days in vitro respectively (groups A, B, and C), and the cells adhesion on the materials was observed by SEM and phalloidine staining, respectively. Cell proliferation activity was measured by cell counting kit 8 method. In vivo, 9 muscle bags were made in dorsal muscles of 9 beagles, respectively. The muscle bags were randomly divided into 3 groups (3 per beagle in each group) and materials 1, 2, and 3 were placed into the muscle bags of groups A, B, and C, respectively. After 1, 2, and 3 months of operation, 3 beagles were anesthetized and the samples were stained with HE, Masson, and Safranin, and the bone formation area ratio in the BCP gap was calculated. Real-time fluorescence quantitative PCR (qRT-PCR) was performed to detect the expressions of bone-related genes [including alkaline phosphatase (ALP), osteopontin (OPN), and osteocalcin (OC)]. The BET test showed that with the increase of sintering temperature, the internal porosity of the particles did not change significantly, but the diameter, volume, and area of the mesopores gradually decreased. The XRD detection showed that the XRD waves of HA and β-TCP could be seen in all 3 kinds of materials; SEM showed that there were widely distributed macropores on the surface of 3 kinds of BCPs, and the interpores connected with the others. In vitro, BMSCs adhered and proliferated on the surfaces of 3 kinds of BCPs, and the cell biocompatibility of the materials in groups B and C was better than that in group A. In vivo, obvious osteoid tissue deposition could be observed in the intergranular space of 3 kinds of BCPs from 2 months after implantation. The bone formation area ratio of each group increased with time. The bone formation area ratio in group A was significantly higher than that in groups B and C at 2 and 3 months after implantation, and in group A than in group B at 1 month ( P<0.05). qRT-PCR showed that the expressions of osteogenic related genes peaked at 2 months in group A, and gradually increased with time in groups B and C. The relative expressions of ALP and OPN mRNAs in group A were significantly higher than those in groups B and C at 1 month after implantation, the relative expression of OC mRNA in group A was significantly higher than that in groups B and C at 2 months after operation, the relative expression of ALP mRNA in groups B and C and the relative expression of OPN mRNA in group B were significantly higher than those in group A, all showing significant differences ( P<0.05); there was no significant difference in the relative expression of each gene among the other groups at each time point ( P>0.05). The mesoporous diameter of BCP decreases with the increase of sintering temperature. Different mesoporous diameters lead to different ectopic osteogenesis of BCP materials. BCP material with mesoporous diameter of 12.57 nm has better osteogenic ability which can activate the osteogenic gene earlier. The mesoporous diameter is expected to be an adjustable index for optimizing the osteogenic capacity of BCP materials.

The Histomorphometry of Rabbit Bone Tissue with Experimental Osteoporosis after Implantation of Biphasic Calcium Phosphate Materials

The histomorphometry of the rabbit bone tissue from the lower jaw was done. Authors hypothesized that local enhancement with biphasic calcium phosphate ceramic materials in the femur trochanter major area increase the trabecular bone volume outside the implantation zone in vivo. Twenty-two California female rabbits were included in this study and were divided into four groups. Four healthy rabbits composed a control group (A group), while other eighteen underwent ovariectomy. Bone defects were created in femur trochanter major region. Sham surgery group (B group) consisted of four female rabbits with osteoporosis and bone defect, but no biomaterials were implanted. In C group (seven rabbits) created defects were filled with granules of biphasic calcium phosphate ceramic (hydroxyapatite (HAP) and tricalcium phosphate (TCP) 30/70); in D group (seven rabbits) defects were filled with the same granules (HAP/TCP 30/70) together with strontium (5% by mass). Twenty-two bone samples were taken from lower jaw premolar region. Trabecular bone area was measured using Image Pro Plus 7 program, where three equal fields (0.975 mm2) of view were at random chosen in all bone samples. Results have shown that the trabecular bone area in A group was 0.201 mm2 (0.176-0.233), which is statistically significantly higher (p &lt;0.0001) than in B group 0.127 mm2 (0.118 – 0.149), C group 0.136 mm2 (0.108 – 0.166) and D group 0.135 mm2 (0.126 – 0.164), respectively. Statistically significant differences between B, C and D groups were not found (p &gt; 0.05).

Staged implant placement after defect regeneration using biphasic calcium phosphate materials with different surface topographies in a minipig model

ObjectiveTo assess the influence of biphasic calcium phosphate materials with different surface topographies on bone formation and osseointegration of titanium implants in standardized alveolar ridge defects.Materials and methodsStandardized alveolar ridge defects (6 × 6 mm) were created in the mandible of 8 minipigs and filled with three biphasic calcium phosphate materials (BCP1–3, 90% tricalcium phosphate/10% hydroxyapatite) with different surface properties (micro- and macroporosities) as well as a bovine-derived natural bone mineral (NBM) as a control. At 12 weeks, implants were placed into the augmented defects. After further 8 weeks of healing, dissected blocks were processed for histological analysis (e.g., mineralized (MT), residual bone graft material (BS), bone-to-implant contact (BIC)).ResultsAll four biomaterials showed well-integrated graft particles and new bone formation within the defect area. MT values were comparable in all groups. BS values were highest in the NBM group (21.25 ± 13.52%) and markedly reduced in the different BCP groups, reaching statistical significance at BCP1-treated sites (9.2 ± 3.28%). All test and control groups investigated revealed comparable and statistically not significant different BIC values, ranging from 73.38 ± 20.5% (BCP2) to 84.11 ± 7.84% (BCP1), respectively.ConclusionAll bone graft materials facilitated new bone formation and osseointegration after 12 + 8 weeks of healing.

THE EFFECT OF MINERAL TRIOXIDE AGGREGATE ALONE AND IN COMBINATION WITH BIPHASIC CALCIUM PHOSPHATE ON HEALING OF MANDIBULAR DEFECTS IN RABBIT

INTRODUCTION: Critical sized bone defects above critical size do not heal completely by themselves and thus represent major clinical challenge to reconstructive surgery. Numerous bone substitutes have already been used to promote bone regeneration. Incorporation of bone grafts such as biphasic calcium phosphate (BCP) as osteoconductive materials has been proven to be effective in promoting bone healing in oral surgery. As it is considered a potential candidate for bone regenerating biomolecules which can help in rapid bone repair because of its composition, the biocompatible material mineral trioxide aggregate(MTA) is suggested to be promising. OBJECTIVES: To compare the efficacy of MTA on the process of bone healing alone and the combination of MTA with biphasic calcium phosphate MATERIALS AND METHODS: Sixteen rabbits will be divided into two experimental groups: (1) MTA, (2) MTA+BCP. Right and left critical size bone defects will be performed in the edentulous area of rabbit mandibles (diastema). Right side bone defects will be filled with MTA, while the left side bone defects will be filled with MTA in combination with BCP. The effect of both MTA and BCP on defect healing will be assessed histologically, histomorphometrically and immunohistochemically after 6 weeks postoperatively. RESULTS: Greater amount of new bone formation was noticed in the CSDs loaded with MTA and BCP. The amount of new bone formed was significantly higher in the MTA+BCP group when compared with the MTA group. Also bone cells activities appeared greater in the former group. CONCLUSIONS: MTA induces new bone formation via an osteoinductive action and can be added to bone grafts to enhance bone regenerative capacity

Comparative Study between Laser Light Stereo-Lithography 3D-Printed and Traditionally Sintered Biphasic Calcium Phosphate Scaffolds by an Integrated Morphological, Morphometric and Mechanical Analysis.

In dental districts, successful bone regeneration using biphasic calcium phosphate materials was recently explored. The present study aimed to perform a comparative study between 3D-printed scaffolds produced by laser light stereo-lithography (SLA) and traditionally sintered biphasic calcium phosphate scaffolds by an integrated morphological, morphometric and mechanical analysis. Methods: Biphasic calcium phosphate (30% HA/70% β-TCP) samples, produced by SLA-3D-printing or by traditional sintering methods, were tested. The experimental sequence included: (1) Microtomography (microCT) analyses, to serve as control-references for the 3D morphometric analysis; (2) loading tests in continuous mode, with compression up to fracture, to reconstruct their mechanical characteristics; and (3) microCT of the same samples after the loading tests, for the prediction of the morphometric changes induced by compressive loading of the selected materials. All the biomaterials were also studied by complementary scanning electron microscopy to evaluate fracture regions and surfaces. Results: The characterization of the 3D mineralized microarchitecture showed that the SLA-3D-printed biomaterials offer performances comparable to and in some cases better than the traditionally sintered ones, with higher mean thickness of struts and pores. Interestingly, the SLA-3D-printed samples had a higher ultimate strength than the sintered ones, with a smaller plastic region. Moreover, by SEM observation, it was observed that fractures in the SLA-3D-printed samples were localized in the structure nodes or on the external shells of the rods, while all the traditionally sintered samples revealed a ductile fracture surface. Conclusions: The reduction of the region of plastic deformation in the SLA-3D-printed samples with respect to traditionally sintered biomaterials is expected to positively influence, in vivo, the cell adhesion. Both microCT and SEM imaging revealed that the studied biomaterials exhibit a structure more similar to human jaw than the sintered biomaterials.

Accelerated bone formation by biphasic calcium phosphate with a novel sub-micron surface topography.

Osteoinductive calcium phosphate (CaP) bone grafts have equivalent performance to autografts in repairing critical-size bone defects. The osteoinductive potential of CaP is linked to the size of the surface topographical features. In the present study, two novel biphasic calcium phosphate (BCP) bone grafts were synthesised with either sub-micron- (BCP<µm) or micron-scale (BCPµm) needle-shaped surface topography and compared to dimensionally similar tricalcium phosphate (TCP) with grain-shaped surface structures (TCP<µm and TCPµm). To clarify the possible function of the surface morphology (needle-like vs. grain-like) in initiating bone formation, the four CaP test materials were physicochemically characterised and implanted for 12 weeks in the dorsal muscle of beagles. The sub-micron needle-shaped topography of BCP<µm triggered earlier bone formation (3-6 weeks) as compared to the grain-shaped surface topography of TCP<µm, which formed bone at 6-9 weeks. After 12 weeks, the amount of induced bone formation in both materials was equivalent, based on histomorphometry. The micron-sized needle-shaped surface topography of BCPµm led to limited formation of new bone tissue, whereas its counterpart, TCPµm with grain-shaped surface topography, failed to trigger de novo bone formation. The relative strength of the parameters affecting CaP-driven bone induction was as follows: surface feature size > surface feature morphology > substrate chemistry. BCP materials with needle-shaped sub-micron surface topography gave rise to accelerated bone formation and slower rate of resorption than a comparable TCP. These characteristics may be translated to improve bone healing in orthotopic defects.

Nano-Biphasic Calcium Phosphate Ceramic for the Repair of Bone Defects.

Calcium phosphate bioceramics has recently experienced increased interest in bone reconstruction. Mimicking of natural structure of bone, like the use of nanomaterials, is an attractive approach for generating scaffolds for bone regeneration. The aim of present study was to evaluate the effect of nanonization on the biphasic calcium phosphate (BCP) ceramic in the repair of bone cavities in the canine mandible. A commercial BCP was dry-milled in a high energy planetary ball mill with zirconia balls and container. Three holes (8 mm in diameter) were outlined to the depth of cortical bone of mandibular angle of 5 dogs bilaterally. The first hole (positive control group A, n = 10) was filled in with commercial BCP material. The second hole was loaded with the nanonized BCP (experimental group C, n = 10) and the third one was left untreated (negative control group B, n = 10). The defects were allowed to regenerate for 8 weeks. New bone formation was greater in groups A and C than in B. No difference was seen between group A and group C (P = 0.676). The residual bone material in group C (19.34 ± 8.03) was as much as one-half of that in group A (38.69 ± 7.90%) (P = 0.000). The negative control group B presented the highest amount of soft tissue within the bone defects. The least percentage of marrow space was found in the positive control group (13.23 ± 13.52). Our results depicted that the rate of resorption increased significantly after nanonization even though the nano-sized BCP failed to make a superior regeneration than the ordinary BCP.

Development of a novel 3D glass-ceramic scaffold for endometrial cell in vitro culture

Glass-ceramic and biphasic calcium phosphate materials with 3D architectures to be used as scaffolds for endometrial stromal cells (ESCs) were synthesized by freezing and lyophilising ceramic suspensions. The microstructures obtained by FESEM showed the presence of open and 3D interconnected porous structures, which are known to promote cell growth and proliferation. Immunohistochemical staining showed that ESCs spread out and ingressed into the Glass-ceramic scaffold. On average, 2952 cells were found per mm3 and the depth of cellular infiltration into the scaffold was 66.4 µm. Embryo development occurred on top of cell-cultured scaffold, which suggests that it is not embryotoxic. Taking all of this into account, we can state that the Glass-ceramic scaffold provides a promising tool to develop an in vitro endometrial 3D model.