Utility of tricalcium phosphate and osteogenic matrix cell sheet constructs for bone defect reconstruction

AIM: To determine the effects of transplanting osteogenic matrix cell sheets and beta-tricalcium phosphate(TCP) constructs on bone formation in bone defects.METHODS: Osteogenic matrix cell sheets were prepared from bone marrow stromal cells(BMSCs), and a porous TCP ceramic was used as a scaffold. Three experimental groups were prepared, comprised of TCP scaffolds(1) seeded with BMSCs;(2) wrapped with osteogenic matrix cell sheets; or(3) both. Constructs were implanted into a femoral defect model in rats and bone growth was evaluated by radiography, histology, biochemistry, and mechanical testing after 8 wk. RESULTS: In bone defects, constructs implanted with cell sheets showed callus formation with segmentalor continuous bone formation at 8 wk, in contrast to TCP seeded with BMSCs, which resulted in bone nonunion. Wrapping TCP constructs with osteogenic matrix cell sheets increased their osteogenic potential and resulting bone formation, compared with conventional bone tissue engineering TCP scaffolds seeded with BMSCs. The compressive stiffness(mean ± SD) values were 225.0 ± 95.7, 30.0 ± 11.5, and 26.3 ± 10.6 MPa for BMSC/TCP/Sheet constructs with continuous bone formation, BMSC/TCP/Sheet constructs with segmental bone formation, and BMSC/TCP constructs, respectively. The compressive stiffness of BMSC/TCP/Sheet constructs with continuous bone formation was significantly higher than those with segmental bone formation and BMSC/TCP constructs.CONCLUSION: This technique is an improvement over current methods, such as TCP substitution, and is useful for hard tissue reconstruction and inducing earlier bone union in defects.

Calcium phosphate cements for bone engineering and their biological properties

Calcium phosphate cements （CPCs） are frequently used to repair bone defects. Since their discovery in the 1980s, extensive research has been conducted to improve their properties, and emerging evidence supports their increased application in bone tissue engineering. Much effort has been made to enhance the biological performance of CPCs, including their biocompatibility, osteoconductivity, osteoinductivity, biodegradability, bioactivity, and interactions with cells. This review article focuses on the major recent developments in CPCs, including 3D printing, injectability, stem cell delivery, growth factor and drug delivery, and pre- vascularization of CPC scaffolds via co-culture and tri-culture techniques to enhance angiogenesis and osteogenesis.

3D printing of calcium phosphate bioceramic with tailored biodegradation rate for skull bone tissue reconstruction

The bone regenerative scaffold with the tailored degradation rate matching with the growth rate of the new bone is essential for adolescent bone repair.To satisfy these requirement,we proposed bone tissue scaffolds with controlled degradation rate using osteoinductive materials(Ca-P bioceramics),which is expected to present a controllable biodegradation rate for patients who need bone regeneration.Physicochemical properties,porosity,compressive strength and degradation properties of the scaffolds were studied.3D printed Ca-P scaffold(3DS),gas foaming Ca-P scaffold(FS)and autogenous bone(AB)were used in vivo for personalized beagle skull defect repair.Histological results indicated that the 3DS was highly vascularized and well combined with surrounding tissues.FS showed obvious newly formed bone tissues.AB showed the best repair effect,but it was found that AB scaffolds were partially absorbed and degraded.This study indicated that the 3D printed Ca-P bioceramics with tailored biodegradation rate is a promising candidate for personalized skull bone tissue reconstruction.

Bone tissue engineering via nanostructured calcium phosphate biomaterials and stem cells

Tissue engineering is promising to meet the increasing need for bone regeneration. Nanostructured calcium phosphate （CAP） biomaterials/scaffolds are of special interest as they share chemical/crystallographic similarities to inorganic components of bone. Three applications of nano-CaP are discussed in this review： nanostructured calcium phosphate cement （CPC）; nano-CaP composites; and nano-CaP coatings. The interactions between stem cells and nano-CaP are highlighted, including cell attachment, orientation/ morphology, differentiation and in vivo bone regeneration. Several trends can be seen： （i） nano-CaP biomaterials support stem cell attachment/proliferation and induce osteogenic differentiation, in some cases even without osteogenic supplements; （ii） the influence of nano-CaP surface patterns on cell alignment is not prominent due to non-uniform distribution of nano-crystals; （iii） nano-CaP can achieve better bone regeneration than conventional CaP biomaterials; （iv） combining stem cells with nano-CaP accelerates bone regeneration, the effect of which can be further enhanced by growth factors; and （v） cell microencapsulation in nano-CaP scaffolds is promising for bone tissue engineering. These understandings would help researchers to further uncover the underlying mechanisms and interactions in nano-CaP stem cell constructs in vitro and in vivo, tailor nano-CaP composite construct design and stem cell type selection to enhance cell function and bone regeneration, and translate laboratory findings to clinical treatments.

Macrophages in Degradation of Calcium Phosphate Compound Artificial Bone： An in vitro Study

The isolated mice peritoneal macrophages in degradation of calcium phosphate compound artificial bone - collagen/hydroxylapatite (CHA). hydroxylapatite (HA), beta-tricalcium phosphate (TCP) ceramics, have been studied by use of both Ca++, P concentration assay in cultured supernatant and scanning electron microscopy (SEM). The solubility of Ca++ . composition of materials increased more significantly when macrophages were inoculated than when macrophages were not seeded (P< 0.001), and it was shown that the ground materials were wrapped and phagocytized or resorbed extracellularly by macrophages under SEM, suggesting that macrophages could mediate the degradation of calcium phosphate compound artificial bone by phagocytizing and/or degrading extracellularly.

Preparation and Compressive Strength of Calcium Phosphate Bone Cement Containing N,O-carboxymethyl Chitosan

N, O-carboxymethyl chitosan （ CMCTS ）, a kind of biodegradable organic substance, was added to calcium phosphate bone cement （CPC） to prodnce a composite more similar in composition to human bone. The compressive strength of the new material was inereased by 10 times compared with conventional CPC.

Porous Calcium Phosphate Ceramic Scaffolds for Tissue Engineering

This study examined the biological response of two porous calcium phosphate ceramics, hydroxyapntite （ HA ） and hydroxyapaptite/β-tricalcium phosphate （ HA/β- TCP ） scaffolds. Three different cell types , a human osteoblastic cell line （ HOS ） , primary human osteoblasts （HOB） and human mesenehymal stem cells （MSCs）, were used to examine biocompatibility and osteoinductive capacity. The experimental results showed both materials were highly biocompatible and proliferation was significantly greater on pure HA （ P 〈 0.01 ）, with a peak in proliferation at day 7. Protein levels were significantly higher （ P 〈 0.05） than the control Thermanox（ TMX （ tm） ） for both test materials. Osteoinduction of MSCs was observed on both test materials, with cells seeded on HA/ β-TCP showing greater alkaline phosphatase activity compared to HA alone, indicating an enhancement in osteoinductive property. Both materials show good potential for use as tissue engineered scaffolds.

The Effect of Premixed Schedule on the Crystal Formation of Calcium Phosphate Cement-chitosan Composite with Added Tetracycline

In this study, calcium phosphate cements （CPC） were prepared by mixing cement powders of tetracalcium phosphate （TTCP） with a cement liquid of phosphate acid saline solution. Tetracycline （TTC）-CPC, chitosan-CPC and chitosan-TTC-CPC were investigated with different premixed schedule. It was demonstrate that both TTC and chitosan worked on the phase transition and crystal characteristics. TTCP mixed with phosphate acid saline solution had similar features of Fourier transform-infrared spectrometry （FT-IR） no matter it was mixed with chitosan or TTC or both. TTC premixed with cement liquid or powder had significant different features of FT-IR and 876 cm-1 seemed to be a special peak for TTC when TTC was premixed with cement liquid. This was also supported by XRD analysis, which showed that TTC premixed with cement liquid improved phase transition of TTCP to OCP. Chitosan, as organic additive, regulates the regular crystal formation and inhibits the phase transition of TTCP to OCP, except when it is mingled with cement liquid premixed with TTC in field scanning electron microscope. It was concluded that the premixed schedule influences the crystal formation and phase transition, which may be associated with its biocompatibility and bioactivities in vivo.

Augmentation of Pedicle Screw Fixation with Calcium Phosphate Cement

To determine whether a biodegradable calcium phosphate cement(CPC) provides significant augmentation of pedicle screw fixation or not,an in vitro biomechanical study was carried out to evaluate the biomechanical effect of CPC in the restoration and augmentation of pedicle screw fixation.Axial pullout test and cyclic bending resistance test were employed in the experiment,and polymethylmethacrylate (PMMA) was chosen as control.The results demonstrate that the pullout strengths following CPC restoration and augmentation are 74% greater on an average than those of the control group,but less than those of PMMA restoration group and augmentation group respectively (increased by 126% versus control).In cyclic bending resistance test,the CPC augmented screws are found to withstand a greater number of cycles or greater loading with less displacement before loosening,but the augmentation effect of PMMA is greater than that of CPC.

The Transformation of Calcium Phosphate Bioceramics in Vivo

To study the transformation process of calcium phosphate bioceramic in vivo,biodegradable porous β-tricalcium phosphate ceramics (β-TCP) were used in this experiment. The materials (5×8mm) were implanted in the tibia of rabbits. The β-TCP ceramics with bone tissue were retrieved and treated for histology, and then observed by using a scanning electron microscope (SEM) and an electron probe X-ray microanalyzer (EMPA) every month. The results show that β-TCP ceramics bond to bone directly,new bones are forming and maturing with materials continuous degrading,and the materials are nearly replaced by the formed bone finally.Parts of the materials were degraded,absorpted and recrystallized,the others dispersped on the cancellous bone and the Haversian lamella with an irregular arrangement incorporating in bone formation directly by remodeling structure.

Biomaterial Based on Doped Calcium Carbonate-Phosphate for Active Osteogenesis

Doped calcium carbonate-phosphate is a biocompatible material that influence actively on the osteogenesis, bone regenerate, strengthening of bone and dental tissues including through the skin. A mechanism of the synthesis reactions of doped nanocrystalline calcium carbonate-phosphate an oscillating type of model for these reactions is proposed. The results indicate that the synthesis involves the formation of hydroxy carbonate complexes from the three calcium carbonate polymorphs (calcite, vaterite, and aragonite) in a solution of ammonium chloride and ammonium carbonate, followed by reaction with orthophosphoric acid. The formation of nanocrystalline calcium carbonate-phosphate doped with Fe2+, Mg2+, Zn2+, K+, Si4+, and Mn2+, has been studied by X-ray diffraction, IR spectroscopy, differential thermal analysis, and energy dispersive X-ray fluorescence analysis. This ensures the preparation of a bioactive material based on octacalcium hydrogen phosphate, and calcium chloride hydroxide phosphates containing cation vacancies. Particle-size analysis data show that the materials contain nanoparticles down to 10 nm in size. Heat treatment of the doped calcium carbonate phosphates produces calcium hydroxyapatite containing cation vacancies, which can be used as a bioactive ceramic.

Development of an Experimental Phosphate-Calcium Cement with a Whisker-Like Structure

In a previous study, the authors tried to synthesize dental materials from dental waste, which was accomplished with alginate impression materials and gypsum. A powder was set by mixing it with phosphate solution. Fibrous curled crystals were found through SEM observation. The present study shows a detailed analysis of the crystals. XRD analysis indicated the crystals are Brushite. A unique profile of the crystal shows it can be a good apatite precursor or cell scaffold;however, this hypothesis requires further examination.

Injectable bone cements:What benefits the combination of calcium phosphates and bioactive glasses could bring?

Out of the wide range of calcium phosphate(CaP)biomaterials,calcium phosphate bone cements(CPCs)have attracted increased attention since their discovery in the 1980s due to their valuable properties such as bioactivity,osteoconductivity,injectability,hardening ability through a low-temperature setting reaction and moldability.Thereafter numerous researches have been performed to enhance the properties of CPCs.Nonetheless,low mechanical performance of CPCs limits their clinical application in load bearing regions of bone.Also,the in vivo resorption and replacement of CPC with new bone tissue is still controversial,thus further improvements of high clinical importance are required.Bioactive glasses(BGs)are biocompatible and able to bond to bone,stimulating new bone growth while dissolving over time.In the last decades extensive research has been performed analyzing the role of BGs in combination with different CaPs.Thus,the focal point of this review paper is to summarize the available research data on how injectable CPC properties could be improved or affected by the addition of BG as a secondary powder phase.It was found that despite the variances of setting time and compressive strength results,desirable injectable properties of bone cements can be achieved by the inclusion of BGs into CPCs.The published data also revealed that the degradation rate of CPCs is significantly improved by BG addition.Moreover,the presence of BG in CPCs improves the in vitro osteogenic differentiation and cell response as well as the tissue-material interaction in vivo.

Graphene oxide coated three-dimensional printed biphasic calcium phosphate scaffold for angiogenic and osteogenic synergy in repairing critical-size bone defect

The custom-tailored medicine requires a developmental strategy that integrates excellent osteogene-sis with mechanical stability to enhance the reconstruction of the critical-size bone defect(CSBD)and the healing process in weight-bearing bone.We prepared three-dimensional(3D)printed biphasic cal-cium phosphate(BCP)scaffolds composited with nano-graphene oxide(GO).The biological effects of the GO/BCP composite scaffolds could induce the differentiation of rat bone marrow stem cells(BM-SCs)and the migration of human umbilical vein endothelial cells(HUVECs)for bone repair.The proper ratio of GO in the composite scaffold regulated the composites’surface roughness and hydrophilicity to a suitable range for the adhesion and proliferation of BMSCs and HUVECs.Besides,the GO/BCP composite scaffold increased osteogenesis and angiogenesis by activating BMP-2,RUNX-2,Smad1/4,and VEGF.The customized intramedullary nail combined with GO/BCP scaffold was applied to repair CSBD(2.0 cm in length)in a beagle femur model.This fixation strategy was confirmed by finite element analysis.In vivo,the results indicated that the custom-made internal fixation provided sufficient stability in the early stage,ensuring bone healing in a considerable mechanical environment.At 9 months postoperatively,longitudi-nal bony union and blood vessels in osteon were observed in the CSBD area with partial degradation in the 0.3%GO/BCP group.In the three-point bending test,the ultimate load of 0.3%GO/BCP group reached over 50%of the normal femur at 9 months after repair.These results showed a promising application of osteogenic GO/BCP scaffold and custom-made intramedullary nails in repairing CSBD of the beagle femur.This effective strategy could provide an option to treat the clinical CSBD in weight-bearing bones.

Bone without borders-Monetite-based calcium phosphate guides bone formation beyond the skeletal envelope

Calcium phosphates(CaP)represent an important class of osteoconductive and osteoinductive biomaterials.As proof-of-concept,we show how a multi-component CaP formulation(monetite,beta-tricalcium phosphate,and calcium pyrophosphate)guides osteogenesis beyond the physiological envelope.In a sheep model,hollow dome-shaped constructs were placed directly over the occipital bone.At 12 months,large amounts of bone(~75%)occupy the hollow space with strong evidence of ongoing remodelling.Features of both compact bone(osteonal/osteon-like arrangements)and spongy bone(trabeculae separated by marrow cavities)reveal insights into function/need-driven microstructural adaptation.Pores within the CaP also contain both woven bone and vascularised lamellar bone.Osteoclasts actively contribute to CaP degradation/removal.Of the constituent phases,only calcium pyrophosphate persists within osseous(cutting cones)and non-osseous(macrophages)sites.From a translational perspective,this multi-component CaP opens up exciting new avenues for osteotomy-free and minimally-invasive repair of large bone defects and augmentation of the dental alveolar ridge.

Bioactive calcium and mangnesium phosphate bone adhesive for enhanced vascularization and bone regeneration

Bone adhesive is a promising material for the treatment of bone fractures,which is helpful for the fast and effective reduction and fixation of broken bones.However,the existing adhesives bond weakly to bone tissues,and are non-absorbable,or hard to cure under wet conditions.Herein,inspired by the cement-based adhesive used in the industry field,we report a bioactive calcium and magnesium phosphate bone adhesive(MPBA)with the properties of facile preparation,robust adhesion,and bioactive.MPBA is equipped with similar strength to cancellous bones and shows reliable bonding performance for various interfaces,such as Ti6Al4V,Al2O3,and poly(ether-ether-ketone).MPBA achieves excellent bonding ability for the above interfaces with the bonding strengths of 2.28±0.47,2.32±0.15,and 1.44±0.38 MPa,respectively.Besides,it also shows reliable fixation ability for bovine bone surfaces.The bonding behavior to materials and bones suggests that MPBA could be used for both fracture treatment and implant fixation.Meanwhile,MPBA possesses good biological activity,which could promote the vascularization process and osteogenic differentiation.Finally,in vivo experiments confirmed MPBA can effectively restore bone strength and promote bone regeneration.

双能量CT联合肌骨超声鉴别诊断焦磷酸钙沉积病与痛风性关节炎的价值

目的 探究双能量CT联合肌骨超声鉴别诊断焦磷酸钙沉积病与痛风性关节炎的价值。方法 回顾性分析痛风性关节炎102例和焦磷酸钙沉积病102例患者的病历资料,分别记为痛风组和钙沉积组。所有患者均行双能量CT和肌骨超声检查,并以关节滑液或关节腔内晶体物质的穿刺结果作为金标准。评估双能量CT、肌骨超声诊断焦磷酸钙沉积病与痛风性关节炎的效能。结果 痛风组患者的男性比例、血尿酸均高于钙沉积组(P <0.05)。痛风组患者中膝关节、第一跖趾关节、踝关节的受累率偏高,钙沉积组患者中膝关节、腕关节、肩关节的受累率偏高。痛风组患者的骨皮质不规则、软骨损伤、半月板退行性变的所占比例均低于钙沉积组(P <0.05)。痛风组患者的双轨征、痛风石、韧带内强回声、肌腱内强回声、骨侵蚀占比高于钙沉积组(P <0.05),软骨钙化低于钙沉积组(P <0.05)。双能量CT、肌骨超声及二者联合诊断焦磷酸钙沉积病和痛风性关节炎的灵敏度分别为86.27%、83.33%、94.12%,特异度分别为89.22%、88.24%、86.27%,阳性预测值分别为88.89%、87.63%、87.27%,阴性预测值分别为86.67%、84.11%、93.63%,准确率分别为87.75%、85.78%、90.20%,一致性Kappa值分别为0.755、0.716、0.804。结论 双能量CT联合肌骨超声在焦磷酸钙沉积病与痛风性关节炎中的诊断效能良好,可用于辅助鉴别诊断两种疾病。

髓芯减压联合骨形成蛋白活性诱导棒植入术治疗早期股骨头坏死的效果

目的探讨髓芯减压联合骨形成蛋白(BMP)活性诱导棒植入术治疗早期股骨头坏死的效果。方法回顾性分析2018年6月至2022年6月收治的116例早期股骨头坏死患者,按照不同的手术方式分为髓芯减压联合BMP活性诱导棒组(BMP组)和同种异体骨组。BMP组60例,采用髓芯减压联合BMP活性诱导棒植入术治疗。同种异体骨组56例,采用髓芯减压联合同种异体骨打压植骨术治疗。对比两组患者术前、术后6个月和术后1年的髋关节Harris评分、疼痛视觉模拟评分(VAS)的差异,并对患者术后1年疗效和股骨头存活率进行比较。结果所有患者均获得随访,两组患者术前VAS评分、Harris评分差异无统计学意义(P>0.05),术后6个月、1年时两组患者VAS评分、Harris评分均显著改善,且BMP组优于同种异体骨组,差异有统计学意义(P<0.05)。术后1年时,BMP组Harris髋关节评分优良率高于同种异体骨组,差异有统计学意义(P<0.05);BMP组股骨头存活率高于同种异体骨组,差异有统计学意义(P<0.05)。结论髓芯减压联合BMP活性诱导棒植入术治疗早期股骨头坏死早期具有疗效,能够加速诱导新骨生成,提高新骨质量,为股骨头提供生物力学支撑,有效避免股骨头塌陷,且生物相容性好、能够在体内降解吸收,值得在临床上推广。

磷酸钙复合重组人骨形态发生蛋白2修复和重建胫骨感染性骨缺损

背景:尽管Masquelet技术在临床的应用取得了广泛成功,但目前优化该技术各个环节的研究仍在不断开展,其中加快植骨后骨愈合速度、缩短骨愈合时间是医生关注的焦点。目的:观察磷酸钙复合重组人骨形态发生蛋白2材料修复胫骨感染性骨缺损的效果。方法:选择2017年6月至2022年6月简阳市人民医院收治的感染性胫骨缺损患者31例,均接受Masquelet技术分期治疗,二期手术根据植骨材料的不同分为对照组(n=15)与研究组(n=16),对照组植入异体骨/自体骨颗粒,研究组植入磷酸钙复合重组人骨形态发生蛋白2/自体骨颗粒。二期术后6个月,检测患者外周血白细胞数、C-反应蛋白、血沉等炎性指标,记录影像学骨愈合时间、骨愈合X射线评分、骨缺损愈合分级和邻近关节功能,观察是否存在钉道感染、植入吸收、取骨区疼痛、感染等情况。结果与结论:①两组患者二期术后6个月外周血白细胞计数、血沉、C-反应蛋白水平均低于一期术前(P<0.05),两组间各指标比较差异无显著性意义(P>0.05);②研究组骨愈合时间短于对照组(P<0.05);③研究组患者二期术后6个月的骨愈合X射线评分高于对照组(P<0.05),骨缺损愈合优良率与邻近关节功能优良率均高于对照组(P<0.05);两组间感染复发率与并发症发生率比较差异均无显著性意义(P>0.05);④结果表明,Masquelet技术二期术中应用磷酸钙复合重组人骨形态发生蛋白2治疗胫骨感染性骨缺损的愈合效果良好、安全性高。

明胶/二水磷酸氢钙/二水硫酸钙复合多孔支架材料的制备与性能研究

以二水磷酸氢钙、α-半水硫酸钙为原料,利用搅拌干燥喷雾法制备二水磷酸氢钙/二水硫酸钙核壳结构复合球状颗粒,并将球状颗粒与明胶进行复合,之后在模具成型的方法,最终制备出明胶/二水磷酸氢钙/二水硫酸钙复合多孔生物支架。通过XRD、SEM等方法对制备出的复合多孔支架材料进行了检测,研究分析了支架材料的成分、形貌以及内部的结构特征,并就支架材料的体外降解性、孔隙率、力学性能和细胞毒性等进行了探究。结果表明:明胶/二水磷酸氢钙/二水硫酸钙复合多孔支架有一定的孔洞结构,平均初始孔隙率达到61%,可以满足骨组织工程对于支架材料的要求;并且支架材料具有良好的抗压强度,平均数值达到(6.1±0.05)MPa;该复合多孔支架的体外模拟体液浸泡降解周期约80 d,无细胞毒性,在骨组织修复方面具有良好的应用前景。