Traditional Calcium Phosphate Cement Research Articles

A Biphasic Calcium Phosphate Cement Enhances Dentin Regeneration by Dental Pulp Stem Cells and Promotes Macrophages M2 Phenotype In Vitro.

Calcium phosphate cement (CPC) is promising for bone and dentin repair and regeneration. However, there has been no report of biphasic CPC for inducing dentin regeneration. The aim of this study was to develop a novel biphasic CPC containing β-tricalcium phosphate (β-TCP), and investigate its effects on odontogenic differentiation of human dental pulp stem cells (hDPSCs) and macrophage polarization. New biphasic CPC was formulated with different ratios of β-TCP to an equimolar mixture of tetracalcium phosphate and dicalcium phosphate anhydrous. Mechanical properties, biocompatibility, and odontogenic differentiation induction ability of the cements and the inflammatory reaction to the cements were examined. A series of CPC containing β-TCP were developed. CPC with 20% β-TCP exhibited homogeneity and injectability, an acceptable setting time, and a twofold increase in compressive strength. Significant increases in hDPSCs' alkaline phosphatase activity, mineral deposit, DMP1 and DSPP gene, and protein expressions were obtained for 20% TCP-CPC, compared with traditional CPC (p < 0.01). The addition of β-TCP did not promote macrophage polarization to the proinflammation phenotype. The addition of 10% and 20% β-TCP promoted macrophage polarization to the anti-inflammatory phenotype. In conclusion, a biphasic β-TCP-modified CPC was developed for the first time, demonstrating substantially increased dentin regeneration capability, while promoting macrophages to an anti-inflammation phenotype. The novel biphasic CPC is promising for tooth tissue engineering and dentin regeneration applications. Impact statement Dental pulp exposure from dental caries, wounds, or deep cavity preparation can cause pain and infection, which may lead to root canal treatment or tooth extraction. Maintaining pulp vitality is a major challenge in stomatology. We developed a new injectable β-tricalcium phosphate (β-TCP)-calcium phosphate cement (CPC) for the regeneration of dentin. Compared with traditional CPC, the new CPC +20%TCP possessed good cytocompatibility, acceptable injection force, higher compressive strength (increased by 63%), and greater odontogenic expression and mineral deposits (increased by more than twofolds), while avoiding any proinflammatory drawback. This new biphasic CPC is promising for dental pulp-capping, base, and liner applications to promote dentin regeneration, as well as potentially for bone tissue engineering applications, which warrant further studies.

The pH-Dependent Properties of the Biphasic Calcium Phosphate for Bone Cements

Self-setting calcium phosphate cement (CPC) has been used in bone repair and substitution due to their excellent biocompatibility, bioactive as well as simplicity of preparation and use. The inherent brittleness and slow degradation are the major disadvantages for the use of calcium phosphate cements. To improve the degradation for the traditional CPC, the apatite cement formula incorporated with β-tricalcium phosphate (β-TCP) with varying concentration were studied and the effect of the pH value of liquid phase on the properties of this new calcium phosphate cement formula was evaluated. The apatite cements containing β-TCP for 10 and 40 wt.% were mixed into the aqueous solution with different pH values and then aging in absolute humidity at 37°C for 7 days. The setting time and phase analysis of the biphasic calcium phosphate were determined as compared to the apatite cement. For proper medical application, the compressive strength, the phase analysis and the degradation of the CPC samples at pH 7.0 and 7.4 were evaluated after soaking in the simulated body fluid (SBF) at 37°C for 7 days. The results indicated that the properties of the samples such as the setting time, the compressive strength related to the phase analysis of the set cements. The high degradation of the CPC was found in the cement with increasing β-TCP addition due to the phase after setting. Apatite formation with oriented plate-like morphology was also found to be denser on the surface of the biphasic bone cements after soaking in SBF for 7 days. The obtained results indicated that the cement containing β-TCP mixed with the liquid phase at pH 7.4 could be considered as a highly biodegradable and bioactive bone cement, as compared to the traditional CPC.

Induced pluripotent stem cell-derived mesenchymal stem cell seeding on biofunctionalized calcium phosphate cements.

Induced pluripotent stem cells (iPSCs) have great potential due to their proliferation and differentiation capability. The objectives of this study were to generate iPSC-derived mesenchymal stem cells (iPSC-MSCs), and investigate iPSC-MSC proliferati on and osteogenic differentiation on calcium phosphate cement (CPC) containing biofunctional agents for the first time. Human iPSCs were derived from marrow CD34+ cells which were reprogrammed by a single episomal vector. iPSCs were cultured to form embryoid bodies (EBs), and MSCs migrated out of EBs. Five biofunctional agents were incorporated into CPC: RGD (Arg-Gly-Asp) peptides, fibronectin (Fn), fibronectin-like engineered polymer protein (FEPP), extracellular matrix Geltrex, and platelet concentrate. iPSC-MSCs were seeded on five biofunctionalized CPCs: CPC-RGD, CPC-Fn, CPC-FEPP, CPC-Geltrex, and CPC-Platelets. iPSC-MSCs on biofunctional CPCs had enhanced proliferation, actin fiber expression, osteogenic differentiation and mineralization, compared to control. Cell proliferation was greatly increased on biofunctional CPCs. iPSC-MSCs underwent osteogenic differentiation with increased alkaline phosphatase, Runx2 and collagen-I expressions. Mineral synthesis by iPSC-MSCs on CPC-Platelets was 3-fold that of CPC control. In conclusion, iPSCs showed high potential for bone engineering. iPSC-MSCs on biofunctionalized CPCs had cell proliferation and bone mineralization that were much better than traditional CPC. iPSC-MSC-CPC constructs are promising to promote bone regeneration in craniofacial/orthopedic repairs.

Related research on a novel macropores calcium phosphate cement as bone tissue engineering scaffold

Objective To investigate the cell toxicity of a novel macropores calcium phosphate cement (CPC) scaffold and its influence on cell adhesion,growth and proliferation.Methods A novel CPC material was synthesized by means of adding mannitol porogens and applying sodium solution as the cement liquid.The cell growth and proliferation in the novel CPC material extraction was observed by CCK8 assay.Scanning electron microscopy was used to observe hole diameter of the material,cell adhesion and growth in the material.The experiment of three point bending was used to test the biomechanic performance of the CPC material.Results The novel CPC material reached hole diameter value of (267.43±118.01)μm,microporosity of (66.15±6.91)％.Maximum load,flexural strength and toughness of the novel CPC material was increased about one time compared to the traditional CPC (P＜0.05).CCK8 assay showed there were no significant difference of the light absorption value of cells in the CPC extraction in the 4th,6th,8th day compare to the control group (P＞0.05).Conclusion The novel CPC material has the strong biomechanics performance,macropores,high microporosity and excellent biocompatibility,which is promising for ideal bone tissue engineering scaffold. Key words: Calcium phosphate cement; Mannitol; Bone tissue engineering; Biomechanics; Biocompatibility

Non-rigid calcium phosphate cement containing hydrogel microbeads and absorbable fibres seeded with umbilical cord stem cells for bone engineering

The need for bone repair has increased as the population ages. Non-rigid calcium phosphate scaffolds could provide compliance for micro-motions within the tissues and yet have load-supporting strength. The objectives of this study were to: (a) develop a non-rigid calcium phosphate cement (CPC) with microbeads and fibre reinforcement; and (b) investigate human umbilical cord mesenchymal stem cell (hUCMSC) proliferation, osteodifferentiation and mineralization on non-rigid CPC for the first time. Non-rigid CPC was fabricated by adding extra tetracalcium phosphate in the traditional CPC and by incorporating chitosan, absorbable fibres and hydrogel microbeads. The non-rigid CPC-microbead scaffold possessed a strain-at-failure of 10.7%, much higher than the traditional CPC's strain of 0.05% which is typical for brittle bioceramics. Flexural strength of non-rigid CPC-microbead was 4-fold that of rigid CPC-microbead scaffold, while work-of-fracture (toughness) was increased by 20-fold. The strength of non-rigid CPC-microbead-fibre scaffold matched that of cancellous bone. hUCMSCs on non-rigid CPC proliferated from 100 cells/mm(2) at 1 day to 600 cells/mm(2) at 8 days. Alkaline phosphatase, osteocalcin and collagen gene expressions of hUCMSCs were greatly increased, and the cells synthesized bone minerals. hUCMSCs on non-rigid CPC-microbead-fibre constructs had higher bone markers and more mineralization than those on rigid CPC controls. In conclusion, this study developed the first non-rigid, in situ-setting calcium phosphate-microbead-fibre scaffold with a strain-at-failure exceeding 10%. hUCMSCs showed excellent proliferation, osteodifferentiation and mineralization on non-rigid CPC scaffold. The novel non-rigid CPC-hUCMSC construct with good strength, high strain-at-failure and toughness, as well as superior stem cell proliferation, osteodifferentiation and mineralization, is promising for load-bearing bone regeneration applications.

Premixed acidic calcium phosphate cement: Characterization of strength and microstructure

By using a premixed calcium phosphate cement (CPC), the handling properties of the cement are drastically improved, which is a challenge for traditional injectable CPCs. Previously premixed cements have been based on apatitic cements. In this article, acidic cement has been developed and evaluated. Monocalcium phosphate monohydrate and beta-tricalcium phosphate were mixed with glycerol to form a paste. As the paste does not contain water, no setting reaction starts and thus the working time is indefinite. Powder/liquid ratios (P/L) of 2.25, 3.5 and 4.75 were evaluated. Setting time (ST) and compressive strength (CS) were measured after 1 day, 1 week and 4 weeks in phosphate buffered saline (PBS) solution, and the corresponding microstructure was evaluated using electron microscopy and X-ray diffraction. The ST started when the cements were placed in PBS and ranged from 28 to 75 min, higher P/L gave a lower ST. Higher P/L also gave a higher CS, which ranged from 2 to 16 MPa. The microstructure mainly consisted of monetite, 1-5 microm in grain size. After 4 weeks in PBS, the strength increased. As acidic cements are resorbed faster in vivo, this cement should allow faster bone regeneration than apatitic cements. Premixed cements show a great handling benefit when compared with normal CPCs and can be formulated with similar ST and mechanical properties.

In vitro and in vivo evaluation of an injectable premixed calcium phosphate cement; cell viability and immunological response from rat

By using premixed calcium phosphate cement (CPC) the handling properties of the cement are drastically improved, which is a challenge for traditional injectable CPC. In this article, a premixed acidic CPC has been compared to a conventional water mixed brushite cement to evaluate whether the premixed concept affects the biological response. The cements were evaluated regarding the pH-variation in simulated body fluid (SBF). Further, the biocompatibility of the cement with human mesenchymal stem cells (MSC) was studied in vitro and eventual inflammation properties studied in vivo, after subcutaneous material injections in rats. A larger pH decrease was seen for the conventional cement than the premixed cement in SBF. For both materials, > 90% of the MSC remained alive in vitro. No systemic or macroscopic inflammation was detected, only a mild microscopic inflammation was detected around both materials. In addition to the handling benefit of premixed cements compared to conventional water mixed CPC, the premixed CPC in the present study demonstrated high and in comparison to conventional CPC comparable biocompability, both in vitro and in vivo.