Understanding of dopant-induced osteogenesis and angiogenesis in calcium phosphate ceramics

Various synthetic materials were developed to be used for implant dentistry and periodontal treatments. Among the various synthetic bone substitutes, calcium phosphate ceramics have been extensively investigated because their mineral chemistry resembles that of human bone. We evaluated the regeneration of three calcium phosphate synthetic block bone grafts in rabbit calvarial noncritical size defects. Four 8-mm-diameter defects were created in each rabbit (N = 10). Three defects, hydroxyapatite (HA), beta-tricalcium phosphate (β-TCP), and biphasic calcium phosphate (BCP), were randomly filled with one of three fabricated synthetic block bone graft materials. The fourth defect was filled with blood clots. Specimens were harvested at 4 and 8 weeks postsurgery. Histological and histometrical findings indicated that all three calcium phosphate block bone graft materials were able to maintain space significantly better than the control group at both 4 and 8 weeks. In the BCP group, the amount of newly formed bone was increased more than for the other groups. Additionally, β-TCP showed a large resorption of graft materials after 4 weeks postsurgery, while there were only small resorption for HA and BCP.

The role of ENPP1/PC-1 in osteoinduction by calcium phosphate ceramics

Aim: The purpose of the study was to identify the role of SATB2 in healing of the experimental mandible bone tissue defect filling with a synthetic bone graft material and electrical stimulation impact. Materials and Methods: An experiment was carried out on 48 mature male rats of the WAG population, which were divided into 4 groups. Each group included 12 experimental animals. Group 1 included rats that were modeled with a perforated defect of the lower jaw body. Group 2 included animals that were modeled with a perforated defect similar to group 1. In animals, a microdevice for electrical action was implanted subcutaneously in the neck area on the side of the simulated bone defect. The negative electrode connected to the negative pole of the battery was in contact with the bone defect. The battery and electrode were insulated with plastic heat shrink material. Group 3 included rats that were modeled with a perforated defect similar to previous groups, the cavity of which was filled with synthetic bone graft "Biomin GT" (RAPID, Ukraine). Group 4 included animals that were modeled with a perforated defect similar to groups 1-3, the cavity of which was filled with synthetic bone graft "Biomin GT" (RAPID, Ukraine). The simulation of electrical stimulation was the same as in group 2. The material for the morphological study was a fragment of the body of the lower jaw from the zone of the perforated defect. Immunohistochemical study was performed using rabbit anti-human SATB2 monoclonal antibody. Results: In the regenerate filling the defect in the bone tissue of the lower jaw of rats, there was an increase in SATB2 expression under conditions of electrical stimulation; filling the defect with a synthetic bone graft material; simultaneous filling the defect with a synthetic bone graft material and electrical stimulation. The most pronounced expression of SATB2 was observed under conditions of simultaneous filling the defect with a synthetic bone graft material and electrical stimulation; minimally expressed - in conditions of filling the defect with a synthetic bone graft material; moderately expressed - under conditions of electrical stimulation. In the regenerate, in cases of all treatment methods, SATB2 was expressed by immune cells, fibroblastic differon cells, osteoblasts, and in case of electrical stimulation, also by adipocytes, vascular pericytes and endothelial cells, epidermis. Conclusions: The activation of SATB2 expression identified by the authors is one of the mechanisms for stimulating reparative osteogenesis under the conditions of electrical stimulation; filling the defect with a synthetic bone graft material; simultaneous filling the defect with a synthetic bone graft material and electrical stimulation.

A magnetic field has been applied to accelerate bone healing for a long time. In this study, in order to combine the bone repair capability of calcium phosphate (CaP) ceramics with the magnetic field, a novel CaP ceramic–magnetic nanoparticle (CaP–MNP) composite was fabricated through integrating the superparamagnetic nanoparticles into the CaP ceramics. Two kinds of CaP ceramics were chosen: hydroxyapatite (HA) and HA/tricalcium phosphate (65/35, HT). The samples were cultured with Ros17/2.8 and MG63 cells respectively in vitro to evaluate the cell proliferation and differentiation via MTT and alkaline phosphatase activity tests. In order to find the influence of the magnetic materials on the expression of the bone morphological protein (BMP), the samples composited with BMP-2 were implanted subcutaneously in the fasciae of rat back muscles for 30 days. Compared with ordinary CaP ceramics, the results indicated that the CaP–MNP composite had good biocompatibility and was able to promote cell proliferation and differentiation significantly. The in vivo test showed that the expression of BMP-2 would be accelerated by HT composited with MNPs, and new bone-like tissue formation could be observed. Accordingly, it might be expected that this CaP–MNP composite could become a potential bone substitute or bone tissue engineering scaffold.

3D printing calcium phosphate ceramics with high osteoinductivity through pore architecture optimization

The influence of genetic factors on the osteoinductive potential of calcium phosphate ceramics in mice

Calcium phosphate biomaterials as bone drug delivery systems: a review

Calcium Phosphate Ceramics with Inorganic Additives

Event Abstract Back to Event Surface micropatterning with calcium phosphate ceramics by micromoulding in capillaries David Barata1, 2, Daniel De Melo Pereira1, 2, Alessandro Resmini3, Sjöerd A. Veldhuis3, Clemens A. Van Blitterswijk1, 2, J E. Ten Elshof3 and Pamela Habibovic1, 2 1 MIRA Institute for Miomedical Technology and Technical Medicine, University of Twente, Department of Tissue Regeneration, Netherlands 2 MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Instructive Biomaterials Engineering, Netherlands 3 MESA+ Institute for Nanotechnology, University of Twente, Inorganic Materials Science, Netherlands Introduction: Current design of biomaterials for regenerative medicine is progressing towards greater control over the biological response in vivo, along with the evolution of the concept of biocompatibility from bioinert to bioactive[1]. Surface patterning is a promising method to achieve spatial control over cell behaviour by physico-chemical cues such as surface chemistry or topography[2]. While a variety of techniques exist to develop patterns of polymers or biomolecules, patterning ceramic materials is explored to a lesser extent and requires further research[3]. This is particularly interesting for the field of bone regeneration, where calcium phosphate (CaP) ceramics are widely used for their close resemblance to bone mineral and associated bioactivity in terms of osteoconduction and osteoinduction[4]. Here we present an approach to micropatterning of surfaces with CaPs by employing micromoulding in capillaries (MIMIC), a method previously shown suitable for patterning zirconia[5]. Materials and Methods: MIMIC was employed to create patterns of dibasic calcium phosphate anhydrous (DCPA) on a flat silicon substrate. Briefly, a polydimethylsiloxane (PDMS) mould with grooves was placed on the silicon substrate to create channels. After air plasma, CaP solution was infiltrated and controlled heating facilitated nucleation and crystal growth inside the microchannels. After completion, the PDMS mould was removed. Selected samples were further annealed to convert DCPA into β-tricalcium phosphate (β-TCP). Substrates were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Biocompatibility was assessed by culturing MG-63 osteoblast-like cells on the Si-CaP substrates and analysing cell morphology, metabolic activity and proliferation over a period of 7 days. Results and Discussion: CaP bioceramic patterns were successfully formed by nucleation and growth of crystals in the microchannels. The SEM (Figure 1) and the EDS analyses revealed patterns that were confined to the channels used for patterning. The patterns consisted of flower-like crystals varying in size between 5 and 25 μm. XRD pattern showed peaks characteristic of DCPA (before annealing) and of β-TCP (after annealing). The analysis of cell morphology on the patterns showed the effect of the patterns on cell orientation, an effect that was dependent on the pattern size. Metabolic activity of MG-63 cells showed an increasing trend during the 7-day culture, as did the total DNA amount, confirming the biocompatibility of these materials. The results demonstrated that MIMIC is a suitable technique to fabricate micropatterns of CaP against a chemically different background, and that the created micropatterns can be used to spatially control cell behaviour. Conclusion: MIMIC is a promising technique for patterning of CaP ceramics. Further improvements on the patterning method will focus on obtaining different CaP phases, improving control over the morphology and homogeneity of the CaP pattern, and increasing the complexity of the patterns. DB gratefully acknowledges the financial support of the NIRM (Netherlands Institute of Regenerative Medicine); This research has been in part made possible with the support of the Dutch Province of Limburg

Bioinspired approaches to toughen calcium phosphate-based ceramics for bone repair.

20 - Calcium phosphate coatings

Due to the inherent brittleness and low mechanical strength, it is still a challenge for calcium phosphate (Ca‐P) ceramics to be used in load‐bearing bone defect repair. To achieve a good balance between mechanical strength and osteogenic activity, hollow‐tube‐whisker‐modified biphasic calcium phosphate (BCP) ceramics (BCP‐HW) are successfully fabricated by an in situ growth process in the present study. Compared to the initial BCP ceramics (BCP‐C) and those with solid whiskers, BCP‐HW exhibits larger specific surface area (3.9 times vs BCP‐C) and higher mechanical strength (3.4 times vs BCP‐C), endowing it with stronger stimulation on adhesion, proliferation, and osteogenic differentiation of bone marrow mesenchymal stem cells. In an intramuscular implantation model of canine, BCP‐HW shows excellent osteoinductivity and promotes the maturation of new bone, and the resultant compressive strength of the implant increases to ≈12 MPa at 3 months postoperatively. In another critical‐sized segmental bone defect model of rabbit femur, BCP‐HW has the best repairing effect. After implantation for 6 months, much more new bone ingrowth and higher bending load are observed in BCP‐HW than BCP‐C. Collectively, these findings suggest that the in situ hollow‐tube whisker construction possesses immense potential in expanding the applications of Ca‐P ceramics to load‐bearing bone defect repair.

Efficacité et performance des substituts osseux pour remplacer les allogreffes et autogreffes

The size of surface microstructures as an osteogenic factor in calcium phosphate ceramics

To investigate the roles of macrophages in material-instructed bone formation, two calcium phosphate (TCP) ceramics with the same chemistry but various scales of surface topography were employed in this study. After being implanted subcutaneously in FVB mice for 8 weeks, TCPs (TCP ceramics with submicron surface topography) gave rise to bone formation, while TCPb (TCP ceramics with micron surface topography) did not, showing the crucial role of surface topography scale in material-instructed bone formation. Depletion of macrophages with liposomal clodronate (LipClod) blocked such bone formation instructed by TCPs, confirming the role of macrophages in material-instructed bone formation. Macrophage cells (i.e. RAW 264.7 cells) cultured on TCPs in vitro polarized to tissue repair macrophages as evidenced by gene expression and cytokine production, while polarizing to pro-inflammatory macrophages on TCPb. Submicron surface topography of TCP ceramics directed macrophage polarization via PI3K/AKT pathways with the synergistic regulation of integrin β1. Finally, the tissue repair macrophage polarization on TCPs resulted in osteogenic differentiation of mesenchymal stem cells in vitro. At early implantation in FVB mice, TCPs recruited more macrophages which polarized towards tissue repair macrophages with time. The present data demonstrate the important roles of macrophage polarization in bone formation instructed by calcium phosphate ceramics.