Osteosarcoma cell death induced by innovative scaffolds doped with chemotherapeutics.

Osteosarcoma (OS) cancer treatments include systemic chemotherapy and surgical resection. In the last years, novel treatment approaches have been proposed, which employ a drug-delivery system to prevent offside effects and improves treatment efficacy. Locally delivering anticancer compounds improves on high local concentrations with more efficient tumour-killing effect, reduced drugs resistance and confined systemic effects. Here, the synthesis of injectable strontium-doped calcium phosphate (SrCPC) scaffold was proposed as drug delivery system to combine bone tissue regeneration and anticancer treatment by controlled release of methotrexate (MTX) and doxorubicin (DOX), coded as SrCPC-MTX and SrCPC-DOX, respectively. The drug-loaded cements were tested in an in vitro model of human OS cell line SAOS-2, engineered OS cell line (SAOS-2-eGFP) and U2-OS. The ability of doped scaffolds to induce OS cell death and apoptosis was assessed analysing cell proliferation and Caspase-3/7 activities, respectively. To determine if OS cells grown on doped-scaffolds change their migratory ability and invasiveness, a wound-healing assay was performed. In addition, the osteogenic potential of SrCPC material was evaluated using human adipose derived-mesenchymal stem cells. Osteogenic markers such as (i) the mineral matrix deposition was analysed by alizarin red staining; (ii) the osteocalcin (OCN) protein expression was investigated by enzyme-linked immunosorbent assay test, and (iii) the osteogenic process was studied by real-time polymerase chain reaction array. The delivery system induced cell-killing cytotoxic effects and apoptosis in OS cell lines up to Day 7. SrCPC demonstrates a good cytocompatibility and it induced upregulation of osteogenic genes involved in the skeletal development pathway, together with OCN protein expression and mineral matrix deposition. The proposed approach, based on the local, sustained release of anticancer drugs from nanostructured biomimetic drug-loaded cements is promising for future therapies aiming to combine bone regeneration and anticancer local therapy.

Novel bone cement based on calcium phosphate composited CNT curcumin with improved strength and antitumor properties.

In this study, carboxylated carbon nanotube (CNT)-loaded curcumin (CUR) was blended into calcium phosphate cement (CPC) owing to the poor mechanical properties and single function of CPC as a bone-filling material, and CNT-CUR-CPC with improved strength and antitumor properties was obtained. The failure strength, hydrophilicity, in vitro bioactivity, bacteriostatic activity, antitumor activity, and cell safety of CNT-CUR-CPC were evaluated. The experimental results indicated that the failure strength of CNT-CUR-CPC increased from 25.05 to 45.05 MPa (p < 0.001) and its contact angle decreased from 20.37° to 15.27° (p < 0.001) after the CNT-CUR complex was added into CPC at the rate of 5 wt% and blended. Following soaking in simulated body fluid (m-SBF), the main components of CNT-CUR-CPC were hydroxyapatite (HA) and carbonate hydroxyapatite (HCA). The incorporation of CNT-CUR was beneficial for the deposition of PO43- and CO32-, and it promoted the crystallization of HA and HCA. For CNT-CUR-CPC, the inhibition zone diameter on Staphylococcus aureus was 10.2 ± 1.02 mm (p < 0.001) and it exhibited moderate sensitivity, whereas the inhibition zone diameter on Escherichia coli was 8.3 ± 0.23 mm (p < 0.001) and it exhibited low sensitivity. When compared with the CPC, the cell proliferation rate (RGR %) of the CNT-CUR-CPC decreased by 7.73% (p > 0.05) at 24 h, 17.89% (p < 0.05) at 48 h, and 24.43% (p < 0.001) at 72 h when MG63 cells were cultured on it. In particular, after the MG63 cells were cultured with the CNT-CUR-CPC for 48 h, the number of newly proliferating MG63 cells was significantly reduced, and their growth and adhesion on the surface of the CNT-CUR-CPC were inhibited when compared with the CPC. When 3T3-E1 cells were exposed to the m-SBF immersion solution of CNT-CUR-CPC, the cell proliferation rate (RGR %) was ≥80% (p > 0.05) and the cytotoxicity grade was 0-1. The 3T3-E1 cells were cultured with the m-SBF soaking solution of CNT-CUR-CPC for 24 h, and no significant changes in cell morphology or cytotoxicity were observed. After the 3T3-E1 cells were cultured on CNT-CUR-CPC for 48 h, they could stick to and grow on its surface without adverse reactions. CNT-CUR-CPC had a hemolysis rate of 4.3% (p > 0.05) and did not result in hemolysis and hemagglutination. The obtained CNT-CUR-CPC scaffold material exhibited effective antibacterial activity and cell safety, and could achieve a certain antitumor effect, which has a wide application potential in bone tissue engineering.

Study on injectable silver-incorporated calcium phosphate composite with enhanced antibacterial and biomechanical properties for fighting bone cement-associated infections.

Although commonly used in orthopedic surgery, bone cements often face a high risk of post-operative infection. Developing bone cement with antibacterial capability is an effective path for eliminating implant-associated infections. Herein, the potential of silver ions (Ag+) and silver nanoparticles (AgNPs) in modifying CPC for long-term antibacterial property was investigated. Ag+ ions or AgNPs of various concentrations were incorporated in starch-modified calcium phosphate bone cement (CPB) to obtain Ag+-containing (Ag+@CPB) and AgNPs-containing (AgNP@CPB) bone cements. The results showed that all silver-containing CPBs had setting times of about 25-40 min, compressive strengths of greater than 22 MPa, high cytocompatibility but inhibitory effect on Staphylococcus aureus growth. After soaking for 1 week, the mechanical properties and the cytocompatibility of all cements revealed no significant changes, but only CPB with a relatively high content of Ag+ (H-Ag+@CPB) maintained good antibacterial capability over the tested time period. In addition, all the cements showed high injectability and interdigitating capability in cancellous bone and demonstrated augmentation effect on the cannulated pedicle screws fixation in the Sawbones model. In summary, the sustainable antibacterial capability and enhanced biomechanical properties demonstrated that Ag+ ions were more suitable for the fabrication of antibacterial CPC compared to AgNPs. Also, the H-Ag+@CPB, with good injectability, high cytocompatibility, good interdigitating and biomechanical property in cancellous bone, and sustainable antibacterial effects, bears great potential for the treatments of bone infections or implant-associated infections.

Enhanced Cell Osteogenic Differentiation in Alendronate Acid and Flufenamic Acid Drug-Impregnated Nanoparticles of Mesoporous Bioactive Glass Composite Calcium Phosphate Bone Cement In Vitro.

This study aims to compare the anti-osteoporotic drugs alendronic acid (ALN) and flufenamic acid (FA) alone impregnate into nanoparticles of mesoporous bioactive glass (nMBG), which further composites calcium phosphate cement (CPC) and investigates their in vitro performance. The drug release, physicochemical properties, and biocompatibility of nMBG@CPC composite bone cement are tested, and the effect of the composites on improving the proliferation and differentiation efficiency of mouse precursor osteoblasts (D1 cells) is also investigated. Drug release shows that FA impregnates nMBG@CPC composite, a large amount of FA is released rapidly within 8 h, gradually reaching a stable release within 12 h, followed by a slow and sustained release within 14 days, and then reaches a plateau within 21 days. The release phenomenon confirms that the drug-impregnated nBMG@CPC composite bone cement effectively achieves slow drug delivery. The working time and setting time of each composite are within 4-10 min and 10-20 min, respectively, meeting the operational requirements of clinical applications. The addition of nMBG nanoparticles in the CPC matrix did not prevent the aggregation phenomenon under microstructural observation, thus resulting in a decrease in the strength of the nMBG@CPC composite. However, after 24 h of immersed reaction, the strength of each 5 wt.% nMBG impregnated with different concentrations of FA and ALN is still greater than 30 MPa, which is higher than the general trabecular bone strength. The drug-impregnated nMBG@CPC composites did not hinder the product formation and exhibit biocompatibility. Based on the proliferation and mineralization of D1 cells, the combination of nMBG with abundant FA and ALN in CPC is not conducive to the proliferation of D1 cells. However, when D1 cells are contact cultured for 21 days, alkaline phosphatase (ALP) enzyme activity shows higher ALP secretion from drug-impregnated nMBG@CPC composites than drug-free composites. Accordingly, this study confirms that nMBG can effectively impregnate the anti-osteoporosis drugs FA and ALN, and enhance the mineralization ability of osteoblasts. Furthermore, drug-impregnated nMBG applications can be used alone or in combination with CPC as a new option for osteoporotic bone-filling surgery.

[Effectiveness analysis of modified tibial transverse bone transport technique combined with vancomycin calcium phosphate bone cement local filling and covering in treatment of diabetic foot].

Objective: To investigate the effectiveness of modified tibial transverse bone transport technique combined with vancomycin calcium phosphate bone cement local filling and covering in the treatment of diabetic foot (DF). Methods: The clinical data of 22 DF patients treated with modified tibial transverse bone transport technique combined with vancomycin calcium phosphate bone cement local filling and covering between October 2019 and December 2021 were retrospectively analyzed. There were 13 males and 9 females with an average age of 61.3 years (range, 41-74 years). The duration of diabetes mellitus was 8-30 years, with an average of 12.5 years, and the duration of DF was 10-42 days, with an average of 28.2 days. There were 2 cases of grade 3 and 20 cases of grade 4 according to Wagner classification. CT angiography was performed on both lower extremities of the patients, and the blood vessels of the affected extremities were narrowed to varying degrees and the blood supply was poor. The preoperative skin temperature of affected foot was (28.27±0.91)°C, the ankle brachial index (ABI) was 0.42±0.11, and the visual analogue scale (VAS) score was 7.7±0.6. Preoperative size of DF ulcer ranged from 2.5 cm×2.0 cm to 3.5 cm×3.0 cm. The skin temperature of affected foot, ABI, VAS score, and skin wound healing of the affected foot were recorded and compared between before operation and at 3 months after operation. Results: All patients were followed up 3-18 months, with an average of 10.5 months. The infection of 1 patient with Wagner grade 4 did not improve significantly after operation, and there was a trend of further deterioration, and the amputation of the left leg was finally performed at 22 days after operation.The remaining 21 patients recovered well after operation, the external fixator was removed at 1 month after operation, the wound healed at 3 months after operation, and there was no recurrence of ulcer in situ or other sites during follow-up. At 3 months after operation, the skin temperature of affected foot was (31.76±0.34)°C, the ABI was 0.94±0.08, and the VAS score was 2.1±0.3, which significantly improved when compared with those before operation ( t=25.060, P<0.001; t=32.412, P<0.001; t=-51.746, P<0.001). Conclusion: Modified tibial transverse bone transport technique combined with vancomycin calcium phosphate bone cement local filling and covering for DF patients can effectively improve the blood supply of the affected limb, promote wound healing, and improve effectiveness.

Biopsies from the Distal Radius after Implantation of Calcium Phosphate Cement.

Background: Calcium Phosphate (CaP) bone cement is gradually replaced by new bone when used as a gap-filler. Details of the re-modelling process are still unclear. Uncertainty is also present as to the possible release of cement particles during the resorption phase causing local soft tissue reactions. The objective of this study was to perform a comprehensive histological investigation of the injectable CaP bone cement used as a void filler in corrective radius osteotomies and adjacent tissue reactions. Methods: Fourteen patients, median age 56 years (18-72), 4 men/10 women, underwent removal of distal radius plates (11 dorsal/3 volar) due to tenosynovitis-like symptoms. Eleven study patients went through corrective osteotomies with CaP bone cement and three were control patients. Previous surgery in three controls consisted in (1) corrective osteotomy with bone graft (dorsal plate), and (2) plated distal radius fractures (1 dorsal/1 volar plate). Biopsies were taken of bone-cement-bone junctions (11), bone-bone graft-bone junctions (1), bone (2) and juxtaposing soft tissue (14). The interval from corrective CaP cement surgery to biopsy was median 1.1 (0.6-2.3) years. Results: Biopsies of bone-cement junctions showed the different stages of new bone formation from CaP to immature bone and later mature well-organised bone. The cement showed signs of osteoclast-mediated resorption. Cement particles, macrophages, multinucleated giant cells (MNGC) and plasma cells were observed in most soft tissue biopsies. MNGC with internalised particles were seen. Macrophages were found along and/or within tendon sheaths in all patients in both groups, but rarely containing cement particles. Conclusions: Gradual re-modelling of the cement into well-organised bone was observed confirming osteoclast-osteoblast coupling. There was no indication that cement particles were the cause of the tenosynovitis-like symptoms.

Injectability, Processability, Drug Loading, and Antibacterial Activity of Gentamicin-Impregnated Mesoporous Bioactive Glass Composite Calcium Phosphate Bone Cement In Vitro.

Calcium phosphate cement (CPC) is similar to bone in composition and has plasticity, while mesoporous bioactive glass (MBG) has the advantage of releasing Si, which can promote osteogenic properties and drug loading capacity. A sol-gel-prepared MBG micro-powder (mMBG) and further impregnated antibiotic gentamicin sulfate (Genta@mMBG: 2, 3, and 4 mg/mL) antibiotic were added to CPC at different weight ratios (5, 10, and 15 wt.%) to study CPC's potential clinical applications. Different ratios of mMBG/CPC composite bone cement showed good injectability and disintegration resistance, but with increasing mMBG addition, the working/setting time and compressive strength decreased. The maximum additive amount was 10 wt.% mMBG due to the working time of ~5 min, the setting time of ~10 min, and the compressive strength of ~51 MPa, indicating that it was more suitable for clinical surgical applications than the other groups. The 2Genta@mMBG group loaded with 2 mg/mL gentamicin had good antibacterial activity, and the 10 wt.% 2Genta@mMBG/CPC composite bone cement still had good antibacterial activity but reduced the initial release of Genta. 2Genta@mMBG was found to have slight cytotoxicity, so 2Genta@mMBG was composited into CPC to improve the biocompatibility and to endow CPC with more advantages for clinical application.

Highly bioactive bone cement microspheres based on α-tricalcium phosphate microparticles/mesoporous bioactive glass nanoparticles: Formulation, physico-chemical characterization and in vivo bone regeneration.

Calcium phosphate cement (CPC) is a self-setting, biocompatible and osteoconductive bone cement, however its use as a bone substitute is still limited owing to its low bioactivity (i.e. its slow in vivo resorption and slow new bone formation rate) which is a challenging issue to be addressed. Herein, we report for the first time highly bioactive bone cement microspheres formulated from a cement paste containing α-tricalcium phosphate microparticles (α-TCP) and mesoporous calcium silicate bioactive glass nanoparticles (mesoporous BGn) using a water-in-oil emulsion method. Indeed, bioactive microspheres possess high potential as bone defect fillers for bone regeneration. The α-TCP microparticles were prepared by a solid state synthesis at 1400 ºC while mesoporous BGn were synthesized by template-assissted ultrasound-mediated sol-gel method. The particle size distribution of as-prepared cement microspheres was in the range of 200 - 450 µm with a sphericity index in the range of 0.92 - 0.94. The surface morphology of α-TCP microspheres revealed α-TCP micoparticles with smooth surfaces whereas α-TCP/BGn microspheres unveiled nano-roughened α-TCP microparticles. The as-prepared α-TCP/BGn cement microspheres exhibited larger specific surface area ca 18.6 m2/g, sustained release of soluble silicate (SiO44-) ions (118 ppm within a week) and high protein adsorption capacity (252 mg/g). Notably, the α-TCP/BGn cement microspheres showed excellent in vitro surface bioactivity via formation of massive amounts of bone-like hydroxyapatite spherules and aggregates on their surfaces after soaking in simulated body fluid. Importantly, the in vivo implantation of as-prepared α-TCP/BGn cement microspheres in rat calvarial critical size bone defects for 6 weeks unveiled high in vivo bioactivity in terms of substantial new bone ingrowth and significant new bone formation within the bone defect as evidenced by histological analyses, X-ray radiography and micro-computed tomography evaluations.

Biodegradable Hydrogel Beads Combined with Calcium Phosphate Bone Cement for Bone Repair: In Vitro and In Vivo Characterization.

This study evaluated the in vitro characterizations of biodegradable hydrogel beads with calcium phosphate bone cement (CPC). Commercial fast-setting CPC and hydrogel beads were compared with 25%-volume hydrogel in CPC (C/0.25) in vivo. The histological behaviors and absorption rates of CPC only, hydrogel beads, and hydrogel/CPC composite were measured and compared at 4, 8, and 12 weeks. The results indicated that the C/0.25 composite can be molded and does not disintegrate when immersed in the solution, but this delays the phase transition of the CPC into the product in the early reaction process. The osteoprogenitor D1 cell affinity of the C/0.25 composite was equally competitive with that of the CPC-only. Adding hydrogel beads to CPC did not inhibit cell proliferation as well as differentiation of osteoprogenitor cells. In vivo histological evaluations did not indicate any significant difference in the CPC-only, hydrogel-only, and C/0.25 composite after 4 weeks of implantation; however, significantly less residue was observed in the C/0.25 composite relative to the CPC-only after 8 weeks. After 12 weeks of hydrogel beads implantation, the hydrogel degraded substantially, creating vacancies that were subsequently occupied by a large amount of soft tissue. New bone was formed in large quantities in the C/0.25; therefore, the C/0.25 composite is a promising option for a wide range of dental, craniofacial, and orthopedic applications.

Analysis of the epidemiological status, microbiology, treatment methods and financial burden of hematogenous osteomyelitis based on 259 patients in Northwest China.

Background: The incidence of hematogenous osteomyelitis is on the rise, and the prognosis is poor. There has been no large-scale epidemiological analysis of hematogenous osteomyelitis in the world, and the treatment method is still controversial. Methods: A retrospective case study method was used to collect and analyze clinical data obtained from patients with hematogenous osteomyelitis in a tertiary hospital in Northwest China from January 1, 2011, to December 31, 2020. The aim of this study was to investigate the epidemiological status, microbiological characteristics, treatment and financial burden of hematogenous osteomyelitis in Northwest China to explore the therapeutic effects of different treatment methods, elucidate the epidemiological characteristics of hematogenous osteomyelitis and to provide a basis for the choice of treatment. Results: We included 259 patients with hematogenous osteomyelitis, including 96 patients with acute hematogenous osteomyelitis and 163 patients with chronic hematogenous osteomyelitis. The cause of the disease was not obvious in most patients, the sex ratio of males to females was 1.98, and the three most common infected sites were the tibia, femur and phalanx. Regarding preoperative serum inflammatory markers, the rate of positivity for ESR was the highest at 67.58%. Among pathogenic microorganisms, Staphylococcus aureus was the most common. Regarding the financial burden, the median total cost per patient was 25,754 RMB, and medications accounted for the largest proportion of the main costs. Conclusions: The most common pathogen associated with HO infection was MSSA. Oxacillin has good PK and PD and is recommended as the first-line drug. Some blood-borne bone infections may lead to complications, such as pulmonary infection through bacteremia, which requires early detection to avoid a missed diagnosis. Regarding surgical intervention, debridement plus absorbable calcium sulfate bone cement and calcium sulfate calcium phosphate bone cement exclusion have achieved good therapeutic effects, but they are worthy of further in-depth research. Regarding the financial burden, the median total cost per patient was 25,754 RMB. The financial burden of blood-borne osteomyelitis was lower than that of traumatic osteomyelitis. Among the main costs, drugs accounted for the largest proportion.

In Vitro Evaluation of Calcium Phosphate Bone Cement Composite Hydrogel Beads of Cross-Linked Gelatin-Alginate with Gentamicin-Impregnated Porous Scaffold.

Calcium phosphate bone cement (CPC) is in the form of a paste, and its special advantage is that it can repair small and complex bone defects. In the case of open wounds, tissue debridement is necessary before tissue repair and the subsequent control of wound infection; therefore, CPC composite hydrogel beads containing antibiotics provide an excellent option to fill bone defects and deliver antibiotics locally for a long period. In this study, CPC was composited with the millimeter-sized spherical beads of cross-linked gelatin-alginate hydrogels at the different ratios of 0 (control), 12.5, 25, and 50 vol.%. The hydrogel was impregnated with gentamicin and characterized before compositing with CPC. The physicochemical properties, gentamicin release, antibacterial activity, biocompatibility, and mineralization of the CPC/hydrogel composites were characterized. The compressive strength of the CPC/hydrogel composites gradually decreased as the hydrogel content increased, and the compressive strength of composites containing gentamicin had the largest decrease. The working time and setting time of each group can be adjusted to 8 and 16 min, respectively, using a hardening solution to make the composite suitable for clinical use. The release of gentamicin before the hydrogel beads was composited with CPC varied greatly with immersion time. However, a stable controlled release effect was obtained in the CPC/gentamicin-impregnated hydrogel composite. The 50 vol.% hydrogel/CPC composite had the best antibacterial effect and no cytotoxicity but had reduced cell mineralization. Therefore, the optimal hydrogel beads content can be 25 vol.% to obtain a CPC/gentamicin-impregnated hydrogel composite with adequate strength, antibacterial activity, and bio-reactivity. This CPC/hydrogel containing gentamicin is expected to be used in clinical surgery in the future to accelerate bone regeneration and prevent prosthesis infection after surgery.

Strength and Biocompatibility of Heparin-Based Calcium Phosphate Cement Grafted with Ferulic Acid.

The biomimetic synthesis of carbonated apatites by biomolecule-based templates is a promising way for broadening apatite applications in bone tissue regeneration. In this work, heparin was used as an organic template to prepare uniform carbonate-based apatite nanorods (CHA) and graft ferulic acid (F-CHA) for enhanced bone mineralization. Next, by combining calcium phosphate cement (CPC) with different F-CHA/CPC ratios, a new type of injectable bone cement combined with F-CHA bioactive apatite was developed (CPC + F-CHA). The physicochemical properties, biocompatibility, and mineralization potential of the CPC + F-CHA composites were determined in vitro. The experimental results confirmed the preparation of highly biocompatible CHA and the compatibility of F-CHA with CPC. Although CPC + F-CHA composites with F-CHA (2.5 wt%, 5 wt%, and 10 wt%) showed a significant reduction in compressive strength (CS), compositing CPC with 10 wt% F-CHA yielded a CS suitable for orthopedic repair (CS still larger than 30 MPa). Spectroscopic and phase analyses revealed that the phase of the hydrothermally synthesized CHA product was not modified by the heparin template. Injection and disintegration tests indicated that the CPC + F-CHA composites have good biocompatibility even at 10 wt% F-CHA. D1 osteoprogenitor cells were cultured with the composites for 7 days in vitro, and the CPC + 10%F-CHA group demonstrated significantly promoted cell mineralization compared with other groups. Given these results, the use of over 10% F-CHA in CPC composites should be avoided if the latter is to be applied to load-bearing areas. A stress-shielding device may also be recommended to stabilize these areas. These newly developed biocompatible CPC + F-CHA have great potential as osteoconductive bone fillers for bone tissue engineering.

Performance of Calcium Phosphate Cements in the Augmentation of Sheep Vertebrae-An Ex Vivo Study.

Oil-based calcium phosphate cement (Paste-CPC) shows not only prolonged shelf life and injection times, but also improved cohesion and reproducibility during application, while retaining the advantages of fast setting, mechanical strength, and biocompatibility. In addition, poly(L-lactide-co-glycolide) (PLGA) fiber reinforcement may decrease the risk for local extrusion. Bone defects (diameter 5 mm; depth 15 mm) generated ex vivo in lumbar (L) spines of female Merino sheep (2-4 years) were augmented using: (i) water-based CPC with 10% PLGA fiber reinforcement (L3); (ii) Paste-CPC (L4); or (iii) clinically established polymethylmethacrylate (PMMA) bone cement (L5). Untouched (L1) and empty vertebrae (L2) served as controls. Cement performance was analyzed using micro-computed tomography, histology, and biomechanical testing. Extrusion was comparable for Paste-CPC(-PLGA) and PMMA, but significantly lower for CPC + PLGA. Compressive strength and Young's modulus were similar for Paste-CPC and PMMA, but significantly higher compared to those for empty defects and/or CPC + PLGA. Expectedly, all experimental groups showed significantly or numerically lower compressive strength and Young's modulus than those of untouched controls. Ready-to-use Paste-CPC demonstrates a performance similar to that of PMMA, but improved biomechanics compared to those of water-based CPC + PLGA, expanding the therapeutic arsenal for bone defects. O, significantly lower extrusion of CPC + PLGA fibers into adjacent lumbar spongiosa may help to reduce the risk of local extrusion in spinal surgery.

A Novel Fast-Setting Strontium-Containing Hydroxyapatite Bone Cement With a Simple Binary Powder System.

In recent years, strontium-substituted calcium phosphate bone cement (Sr-CPC) has attracted more and more attentions in the field of bone tissue repair due to its comprehensive advantages of both traditional CPC and Sr ions. In this study, a crucial Sr-containing α-Ca3 - x Sr x (PO4)2 salt has been synthesized using a simplified one-step method at lower synthesis temperature. A novel Sr-CPC has been developed based on the simple binary Sr-containing α-Ca3 - x Sr x (PO4)2/Ca4(PO4)2O cement powder. The physicochemical properties and hydration mechanism of this Sr-CPC at various Sr contents were intensively investigated. The setting product of this Sr-CPC after a set for 72 h is a single-phase Sr-containing hydroxyapatite, and its compressive strength slightly decreased and its setting time extended with the increase of Sr content. The hydration process included the initial formation of the medium product CaHPO4⋅2H2O (30 min∼1 h), the following complete hydration of Ca4(PO4)2O and the initially formed CaHPO4⋅2H2O (2∼6 h), and the final self-setting of α-Ca3 - x Sr x (PO4)2 (6 h∼). The compressive strength of Sr-CPC, which was closely related to the transformation rate of Sr-containing hydroxyapatite, tended to increase with the extension of hydration time. In addition, Sr-CPC possessed favorable cytocompatibility and the effect of Sr ions on cytocompatibility of Sr-CPC was not obvious at low Sr contents. The present study suggests α-Ca3 - x Sr x (PO4)2 is a kind of vital Sr-containing salt source which is useful to develop some novel Sr-containing biomaterials. In addition, the new Sr-containing cement system based on this simple binary α-Ca3 - x Sr x (PO4)2/Ca4(PO4)2O cement powder displayed an attractive clinical application potential in orthopedics.

Combined construction of injectable tissue-engineered bone with CPC and BMMSCs and its study of repair effect on rabbit bone defect model.

OBJECTIVE: to investigate the combined construction of injectable tissue-engineered bone with calcium phosphate bone cement composite (CPC) and bone marrow mesenchymal stem cells (BMMSCs). METHODS: The proliferation activity of BMMSCs encapsulated was detected by CCK8 method on the 7th day after its self-coagulation by CPC. qRT-PCR was used to detect the expressions of mRNA. The microcapsules of BMMSCs combined with CPC were completely filled in the defect site in the experimental group, and the control group not filled. The two groups were sutured and routinely reared, double upper limb X-ray examination performed after operation. RESULTS: Those of two groups were on the rise over time, which were higher at the 1st, 3rd, 5th and 7th days than those at the previous time points (all P<0.05). The relative expressions of ALP and CALCR at the 7th day were higher than those at the day in BMMSCs combined with the CPC group and BMMSCs group (all P<0.05). The relative expression of CALCR was significantly higher in BMMSCs combined with the CPC group than that in the BMMSCs group on the 7th day (P<0.05). CONCLUSION: With good cell activity and biological activity, the combined construction of the tissue-engineered bone with BMMSCs and CPC can be used as an ideal treatment material for bone tissue repair and connection.

CaP cement is equivalent to iliac bone graft in filling of large metaphyseal defects: 2 year prospective randomised study on distal radius osteotomies.

The purpose of this prospective randomised study was to compare the clinical and radiological outcomes of injectable CaP bone cement with corticocancellous bone graft used to fill voids after corrective opening wedge osteotomies in the distal radius. 17 women/3 men, median age 56 (51.3; 61.0), underwent an open-wedge osteotomy of a dorsal malunion in the distal radius randomised to filling the defect either with bone graft (10) or CaP bone cement (10). Dorsal titanium locking plates were used and the wrist was plastered for 8 weeks. Follow-ups for 24 months included X-rays, CT scans, VAS on wrist and iliac crest, grip strength, ROM, Quick-DASH and Gartland & Werley scores. No difference was found between the 2 groups as to clinical outcome or radiological results with no loss of reduction. One bone graft patient developed a pseudarthrosis and one CaP patient suffered a plate fracture 6 months post-operatively. CaP bone cement is a good alternative to bone graft as a void filler in open-wedge osteotomies of the distal radius. The procedure is shorter, easier with the post-operative advantage of no donor site pain. Level of Evidence Randomised controlled trial. Level I evidence.

Trivalent chromium incorporated in a crystalline calcium phosphate matrix accelerates materials degradation and bone formation in vivo.

Remodeling of calcium phosphate bone cements is a crucial prerequisite for their application in the treatment of large bone defects. In the present study trivalent chromium ions were incorporated into a brushite forming calcium phosphate cement in two concentrations (10 and 50 mmol/mol ß-tricalcium phosphate) and implanted into a femoral defect in rats for 3 and 6 month, non-modified brushite was used as reference. Based on our previous in vitro findings indicating both an enhanced osteoclastic activity and cytocompatibility towards osteoprogenitor cells we hypothesized a higher in vivo remodeling rate of the Cr3+ doped cements compared to the reference. A significantly enhanced degradation of the modified cements was evidenced by micro computed tomography, X-ray and histological examinations. Furthermore the formation of new bone tissue after 6 month of implantation was significantly increased from 29% to 46% during remodeling of cements, doped with the higher Cr3+ amount. Time of flight secondary ion mass spectrometry (ToF-SIMS) of histological sections was applied to investigate the release of Cr3+ ions from the cement after implantation and to image their distribution in the implant region and the surrounding bone tissue. The relatively weak incorporation of chromium into the newly formed bone tissue is in agreement to the low chromium concentrations which were released from the cements in vitro. The faster degradation of the Cr3+ doped cements was also verified by ToF-SIMS. The positive effect of Cr3+ doping on both degradation and new bone formation is discussed as a synergistic effect of Cr3+ bioactivity on osteoclastic resorption on one hand and improvement of cytocompatibility and solubility by structural changes in the calcium phosphate matrix on the other hand. STATEMENT OF SIGNIFICANCE: While biologically active metal ions like strontium, magnesium and zinc are increasingly applied for the modification of ceramic bone graft materials, the present study is the first report on the incorporation of low doses of trivalent chromium ions into a calcium phosphate based biomaterial and testing of its performance in bone defect regeneration in vivo. Chromium(III)-doped calcium phosphate bone cements show improved cytocompatibility and both degradation rate and new bone formation in vivo are significantly increased compared to the reference cement. This important discovery might be the starting point for the application of trivalent chromium salts for the modification of bone graft materials to increase their remodelling rate.

Nano­calcium phosphate bone cement based on Si-stabilized α-tricalcium phosphate with improved mechanical properties.

This study aimed to develop nano­calcium phosphate cement (nCPC) and evaluate the effect of nanosized precursors on mechanical, physical and handling properties (injectability and setting time) as well as conversion rate of nano-reactants into nano-hydroxyapatite (nHA). In this study, while alpha tricalcium phosphate (α-TCP, 98wt%) and HA (2wt%) were applied as the powder phase, 2.5wt% NaH2PO4 solution was used as liquid phase of cement. Before nano-CPC preparation, Si-stabilized α-TCP nanopowder with particle size of 10±3.6nm was firstly synthesized in a two-step process of sol-gel followed by mechanical alloying. Moreover, HA nanopowder with particle size of 32±3.6nm was synthesized using sol-gel process. Our results revealed that after 3days of immersion in ringer's solution, reactants almost completely converted to nHA. Moreover, the initial and final setting time of nano-CPC was obtained 6.3±2.1min and 14.3±4.0min, respectively. Furthermore, injectability of this formulation was reached 87.90±2.60%. In addition, our results confirmed that the compressive strength and modulus of nano-CPC enhanced with increasing immersion time in ringer's solution from 9.50±1.27MPa and 0.38±0.07GPa (at 1day) to 18.70±2.23MPa and 0.57±0.15GPa (at 5days), respectively. Finally, in order to evaluate cellular responses to nano-CPC, MG63 cells were cultured on it and cell morphology and cytotoxicity were evaluated. Results revealed that nano-CPC enhanced proliferation and spreading of osteoblast like cells compared to control (tissue culture plate) which could be due to both appropriate physical and chemical properties of nano-CPC which stimulate cell proliferation. Our findings suggest the formation of an injectable nano-CPC with appropriate mechanical, physical and degradation rate which can potentially utilized for filling bone defects.

Incorporation of Collagen in Calcium Phosphate Cements for Controlling Osseointegration.

In this study, we investigated the effect of supplementing a non-dispersive dicalcium phosphate-rich calcium phosphate bone cement (DCP-rich CPC) with type I collagen on in vitro cellular activities and its performance as a bone graft material. Varying amounts of type I collagen were added during the preparation of the DCP-rich CPC. In vitro cell adhesion, morphology, viability, and alkaline phosphatase (ALP) activity were evaluated using progenitor bone cells. Bone graft performance was evaluated via a rat posterolateral lumbar fusion model and osteointegration of the implant. New bone formations in the restorative sites were assessed by micro-computed tomography (micro-CT) and histological analysis. We found that the incorporation of collagen into the DCP-rich CPC was associated with increased cell adhesion, cell viability, and ALP activity in vitro. The spinal fusion model revealed a significant increase in bone regeneration. Additionally, better osseointegration was observed between the host bone and graft with the DCP-rich CPC supplemented with collagen than with the collagen-free DCP-rich CPC control graft. Furthermore, compared to the control graft, the results of micro-CT showed that a smaller amount of residual material was observed with the collagen-containing DCP-rich CPC graft compared with the control graft, which suggests the collagen supplement enhanced new bone formation. Of the different mixtures evaluated in this study (0.8 g DCP-rich CPC supplemented with 0.1, 0.2, and 0.4 mL type I collagen, respectively), DCP-rich CPC supplemented with 0.4 mL collagen led to the highest level of osteogenesis. Our results suggest that the DCP-rich CPC supplemented with collagen has potential to be used as an effective bone graft material in spinal surgery.

Recurrence of Enchondroma in a Middle Finger after Curettage and Back-filling with Calcium Phosphate Bone Cement: a Case Report.

We report a case of recurrence of enchondroma in a middle finger after curettage and back-filling with calcium phosphate bone cement (CPC). The radiograph showed a lytic lesion around the CPC filling which showed no signs of absorption after 12 years. The tumor was curated easily, however, a steel bar was needed to remove the CPC mass in a carefully manner not to break the cortex. CPC has an advantage of immediate biomechanical stability, on the other hand, a disadvantage of being unabsorbed inside of bone. Although enchondroma has a low recurrence rate after surgery generally, in consideration of recurrence, we recommend the use of absorbable materials when a use of artificial bone substitute to fill the defect is planned.