复方Ⅱ型胶原肠溶胶囊治疗类风湿关节炎50例疗效观察

将100例类风湿性关节炎（RA）患者随机分为两组各50例，治疗组服用复方Ⅱ型胶原肠溶胶囊（2次／d，1粒／次），对照组服用Ⅱ型胶原（2次／d，50斗∥次）。治疗8周后，两组关节疼痛、肿胀、压痛、晨僵均显著改善（P〈0．05），实验室指标均有显著改善（P〈0．05）。与对照组比较，治疗组ESR和RF明显改善，（P〈O．05），CRP两组无显著差异（P〉0．05）。治疗组总有效率、显效率明显高于对照组，P均〈0．05；不良反应发生率明显高于对照组（P〈0．05）。认为复方Ⅱ型胶原肠溶胶囊治疗RA效果好。     

日本血吸虫重组Bb（pGEX—Sj26GST）疫苗免疫BALB／c小鼠脾细胞动态观察

目的观察日本血吸虫重组Bb（pGEX—Sj26GST）疫苗免疫BALB／c小鼠后脾细胞增殖、亚群和凋亡的动态变化。方法将疫苗分别经皮下注射（SC组）和鼻腔粘膜接种（IN组）免疫BALB／c鼠,在免疫后O～22周每2周每组随机剖杀4只小鼠,无菌取脾,制成单个悬浮脾细胞,用四甲基偶氮唑盐比色法（MTT法）检测脾细胞增殖水平、用流式细胞仪（FACsort）检测T细胞亚群和脾细胞凋亡状况。结果未刺激及sjAWA刺激时SC组小鼠脾细胞增值水平于免疫后4～20周明显升高,ConA刺激时于4～18周显著升高,均于免疫后8周达最高水平;IN组脾细胞增殖水平原液组、SjAwA组和ConA组分别于2～18周、2～10周及14～18周、2～8周和12～18周显著升高,均于免疫后4周达最大值（P〈0．01或P〈0．05）。SC组和IN组CD＋T细胞分别于免疫后2～14周、2周及6～16周升高,并于8周达峰值（P〈0．01或P〈0．05）;两组CD＋T细胞均于2～20周轻微升高,分别于8周和6周达较高值（P〉0．05）。未刺激和ConA刺激时SC组脾细胞凋亡水平分别于免疫后2～4周、2～6周升高显著,均于免疫后2周达最大值（P〈O．01或P〈O．05）;IN组均于4周显著升高并达峰值（P〈O．01）。结论日本血吸虫重组Bb（pGEX-Sj26GST）疫苗可诱导脾细胞的增殖,增加cD＋T细胞的数目,抑制脾细胞的凋亡而发挥保护性免疫应答。     

六味地黄丸对糖尿病大鼠胰岛β细胞的保护作用

[目的]观察六味地黄丸对糖尿病大鼠胰岛细胞的保护作用。[方法]将自发性2型糖尿病模型鼠——OLETF鼠分为阳性对照组、六味地黄丸组;非糖尿病对照鼠——LETO鼠为阴性对照组。给药32周后,对各组大鼠观察胰岛,检测胰岛β细胞、胰岛中核因子-κB（NF-κB）的表达。[结果]与阴性对照组比较,阳性对照组、六味地黄丸组大鼠均血糖升高（P〈0．05）、胰岛口细胞减少（P〈0．05）、NF-κB表达增加（P〈0．05）;与阳性对照组比较,六味地黄丸组大鼠胰岛β细胞增加（P〈0．05）,NF-κB表达减少（P〈0．05）。[结论]六味地黄丸可能是通过抑制胰岛中NF-κB的表达保护口细胞。     

2型糖尿病血清铁蛋白与胰岛功能的关系

采用化学发光法测定了107例2型糖尿病组（T2DM）和18例正常对照组（C）的血清铁蛋白（SF）水平，并同时检测了血糖、血脂、胰岛素。采用稳态模式评价胰岛分泌功能（HOMA-β）。结果：T2DM组血清SF明显高于C组（P〈0．05）。Spearman相关分析显示，血清SF水平与胰岛β细胞功能之间呈负相关（r=-0．188，P=0．049）。结论：2型糖尿病患者血清SF水平可能与胰岛β细胞功能密切相关。     

2型糖尿病血清铁蛋白与胰岛功能的关系

采用化学发光法测定了107例2型糖尿病组（T2DM）和18例正常对照组（C）的血清铁蛋白（SF）水平，并同时检测了血糖、血脂、胰岛素。采用稳态模式评价胰岛分泌功能（HOMA-β）。结果：T2DM组血清SF明显高于C组（P〈0．05）。Spearman相关分析显示，血清SF水平与胰岛β细胞功能之间呈负相关（r=-0．188，P=0．049）。结论：2型糖尿病患者血清SF水平可能与胰岛β细胞功能密切相关。     

氟对骨髓基质细胞增殖和成骨能力的影响

目的探讨氟对体外培养的大鼠骨髓基质细胞（MSCs）增殖能力与成骨能力的影响。方法体外培养大鼠MSCs。噻唑蓝（MTT）比色法分析不同染氟水平下MSCs的增殖能力；光、电镜下观察不同染氟水平下MSCs成骨转化能力和相应超微结构变化。结果与对照组比较，低水平染氟（0．02mg／L）96h后促进MSCs增殖（P〈0．05）；较高水平染氟（0．05～1．00mg／L）72h即可促进MSCs增殖（P〈0．05或〈0．01）；高水平染氟（10．00、20．00mg／L）对MSCs具有抑制增殖和促细胞凋亡作用（P〈0．01）。较高水平染氟（2．00～20．00mg／L）时MSCs成骨转化受抑（P〈0．01），较低水平染氟（0．01～1．00mg／L）时MSCs成骨转化增强（P〈0．01）。结论低水平染氟促进MSCs增殖。成骨转化能力增强；高水平染氟抑制MSCs增殖，促进细胞凋亡，抑制MSCs成骨转化能力。     

中药联合聚乙二醇干扰素α-2a对慢性乙型肝炎肝纤维化指标及病毒复制的影响

[目的]观察清热利湿、疏肝健脾中药联合聚乙二醇干扰素α-2a（IFNα-2a）对慢性乙型肝炎（CHB）肝纤维化指标及病毒复制的影响。[方法]治疗组60例HBeAg阳性CHB患者,予聚乙二醇IFNα-2a180腭皮下注射,每周1次,疗程48周,同时服用清热利湿、疏肝健脾中药每日1剂,疗程24周;对照组62例仅予聚乙二醇IFNα-2a,用法同治疗组。荧光定量PCR检测乙肝病毒核酸（HBV-DNA）,放射免疫法检测血清肝纤维化指标。[结果]治疗24周时,治疗组HBeAg血清转换率、HBV-DNA定量下降值高于对照组（P〈0．05）,而治疗48周时,虽高于对照组,但差异无统计学意义（P〉0．05）;治疗组血清透明质酸、层黏连蛋白、Ⅳ型胶原、Ⅲ型前胶原肽,较治疗前显著改善（P〈0．01）,且在治疗24周时显著低于对照组（P〈0．05,〈0．01）;治疗48周时肝纤维化指标改善优于对照组,但差异无统计学意义（P〉0．05）;治疗组不良反应轻于对照组（P〈0．05）。[结论]清热利湿、疏肝健脾中药联合聚乙二醇IFNα-2a,可更好抑制乙肝病毒复制,改善血清肝纤维化指标,同时减轻聚乙二醇IFNα-2a的不良反应,使患者更好地坚持治疗。     

Ⅳ型胶原、MMP-2及TIMP-2在妊高征胎盘组织中的表达及意义

选取60例重度子痫前期孕妇（观察组）及30例正常妊娠孕妇（对照组）,以免疫组化S-P法检测两组Ⅳ型胶原、细胞外基质金属蛋白酶-2（MMP-2）及其抑制剂（TIMP-2）的表达并分析其临床意义。结果两组Ⅳ型胶原均主要分布于胎盘绒毛间质,但观察组表达强度明显高于对照组（P〈0．05）;MMP-2及TIMP-2主要分布于滋养细胞跑质,前者在观察组表达明显低于对照组,后者则相反,P均〈0．05。认为MMP-2／TIMP-2协同作用所致胎盘绒毛Ⅳ型胶原明显增加可能是妊娠高血压综合征形成的病理基础。     

高碘对大鼠海马神经细胞凋亡的影响

目的观察长期高碘对大鼠海马神经细胞形态结构及细胞凋亡的影响，并探讨其作用机制。方法SD大鼠随机分为3组：对照组、高碘Ⅰ组、高碘Ⅱ组，分别以含碘量为5、5000、10000μg／L的自来水及普通饲料喂养。6个月时检测血清总甲状腺激素（TT3、TT4）水平；光、电镜下观察神经细胞尼氏小体及超微结构改变；流式细胞仪检测细胞凋亡率及细胞周期的变化；分光光度法检测一氧化氮（NO）水平及一氧化氮合酶（NOS）活性；RT-PCR法检测凋亡相关基因bcl-2、baxmRNA表达。结果对照组、高碘Ⅰ组、高碘Ⅱ组血清TT3、TT4水平呈逐渐下降趋势，组间比较差异无统计学意义。高碘Ⅰ、Ⅱ组光镜下神经元尼氏小体模糊减少，胞质淡染，电镜下细胞核内染色质浓缩成块．聚集在核膜边缘，形成花瓣状、马蹄状等不规则形态，核膜内陷、包裹聚集的染色质形成凋亡小体。海马神经细胞凋亡率高碘Ⅰ、Ⅱ组均较对照组明显升高（P〈0．01），但高碘Ⅰ组、高碘Ⅱ组间比较未见明显差异（P〉0．05）。与对照组相比，高碘I、Ⅱ组S期细胞减少（P〈0．01），G2／M期增加（P〈0．05），G．期无明显变化（P〉0．05）。高碘Ⅰ、Ⅱ组大鼠海马组织NOS活性及NO水平均明显低于对照组（P〈0．01），bcl-2mRNA表达降低（P〈0．01）、baxmRNA表达升高（P〈0、01），但高碘I组、高碘Ⅱ组间未见明显改变（P〉0．05）。结论长期高碘可诱导大鼠海马神经细胞凋亡，细胞周期改变；其机制可能与NOS活性、NO水平降低以及bax过度表达、bcl-2表达下调有关。     

坎地沙坦抑制盐负荷高血压大鼠肾脏氧化应激

目的探讨血管紧张素Ⅱ（AngⅡ）受体拮抗剂坎地沙坦对盐负荷易卒中自发性高血压大鼠（SHR—SP）肾脏氧化应激和氧化型低密度脂蛋白受体1（LOX-1）表达的影响。方法12周龄Wistar-Kyoto（wKY）大鼠和SHRSP予8％高盐饮食。高盐WKY大鼠（n=6）作为对照组，高盐SHRSP随机分为3组：1）坎地沙坦组（Can，n=6），Can1．0mg／（kg·d）灌胃；2）三氯噻嗪组（TCM，n=6），TCM1．6mg／（kg·d）；3）SHRSP组（n=6），给予等量溶媒。用尾部袖套测量法每周检测1次血压。大鼠给药2周后摘取肾脏，留取24h尿量。采用实时定量PCR检测肾脏NAD（P）H氧化酶亚单位p22phox、p47phox和gp91phox mRNA表达，RT—PCR方法检测LOX-1、转化生长因子β1（TGF—β1）和Ⅳ型胶原mRNA的表达。免疫组化检测肾组织gp91phox和LOX-1蛋白表达，ELISA方法检测尿白蛋白排泄，放免法检测肾脏AngⅡ水平，天狼猩红染色观察肾组织胶原表达。结果实验2周后，SHRSP组收缩压显著高于对照组（P〈0．01），Can和TCM均降低高盐SHRSP组的收缩压（P〈0．01），二者间的降压幅度无差别（P〉0．05）。与对照组比较，肾皮质NAD（P）H氧化酶亚单位、LOX-1、TGF-β1和Ⅳ型胶原mRNA的表达、肾组织AngⅡ水平和尿白蛋白排泄，SHRSP组显著增高；Can降低高盐SHRSP肾组织AngⅡ水平（P〈0．01），下调肾皮质NAD（P）H氧化酶亚单位、LOX-1、TGF-β1和Ⅳ型胶原mRNA的表达（P〈0．01），减少尿白蛋白的排泄（P〈0．01），减轻肾组织胶原的沉积。等效降压剂量的TCM对高盐SHRSP肾组织NAD（P）H氧化酶亚单位、LOX-1的表达和尿白蛋白水平无明显影响。结论Can对盐负荷SHRSP的肾脏保护作用，与抑制氧化应激和LOX-1表达有关，可能不一定依赖其降压作用。     

骨水泥在骨质疏松性脊柱压缩骨折的应用与研究现状

骨水泥已广泛应用在脊柱外科领域。在椎体成形术和后凸成形术中应用的主要是三种骨水泥：聚甲基丙烯酸甲酯骨水泥（PMMA）;磷酸钙骨水泥（CPC）,硫酸钙骨水泥（CSC）;掺骨生长因子的其他可注射物。它们各有优缺点。随着骨水泥材料学、生物力学研究的进展,骨水泥的性能不断改进,在此基础上研究的新的骨水泥将能更好的用于脊柱骨折。     

The Influence of Nanosilica on Properties of Cement Based on Tetracalcium Phosphate/Monetite Mixture with Addition of Magnesium Pyrophoshate

The effect of nanosilica on the microstructure setting process of tetracalcium phosphate/nanomonetite calcium phosphate cement mixture (CPC) with the addition of 5 wt% of magnesium pyrophosphate (assigned as CT5MP) and osteogenic differentiation of mesenchymal stem cells cultured in cement extracts were studied. A more compact microstructure was observed in CT5MP cement with 0.5 wt% addition of nanosilica (CT5MP1Si) due to the synergistic effect of Mg₂P₂O₇ particles, which strengthened the cement matrix and nanosilica, which supported gradual growth and recrystallization of HAP particles to form compact agglomerates. The addition of 0.5 wt% of nanosilica to CT5MP cement caused an increase in CS from 18 to 24 MPa while the setting time increased almost twofold. It was verified that adding nanosilica to CPC cement, even in a low amount (0.5 and 1 wt% of nanosilica), positively affected the injectability of cement pastes and differentiation of cells with upregulation of osteogenic markers in cells cultured in cement extracts. Results revealed appropriate properties of these types of cement for filling bone defects.     

Characterization of Tetracalcium Phosphate/Monetite Biocement Modified by Magnesium Pyrophosphate

Magnesium pyrophosphate modified tetracalcium phosphate/monetite cement mixtures (MgTTCPM) were prepared by simple mechanical homogenization of compounds in a ball mill. The MgP₂O₇ was chosen due to the suitable setting properties of the final cements, in contrast to cements with the addition of amorphous (Ca, Mg) CO₃ or newberite, which significantly extended the setting time even in small amounts (corresponding ~to 1 wt% of Mg in final cements). The results showed the gradual dissolution of the same amount of Mg₂P₂O₇ phase, regardless of its content in the cement mixtures, and the refinement of formed HAP nanoparticles, which were joined into weakly and mutually bound spherical agglomerates. The compressive strength of composite cements was reduced to 14 MPa and the setting time was 5–10 min depending on the composition. Cytotoxicity of cements or their extracts was not detected and increased proliferative activity of mesenchymal stem cells with upregulation of osteopontin and osteonectin genes was verified in cells cultured for 7 and 15 days in cement extracts. The above facts, including insignificant changes in the pH of simulated body fluid solution and mechanical strength close to cancellous bone, indicate that MgTTCPM cement mixtures could be suitable biomaterials for use in the treatment of bone defects.     

Preparation and Characterization of Injectable Brushite Filled-Poly (Methyl Methacrylate) Bone Cement

Powder-liquid poly (methyl methacrylate) (PMMA) bone cements are widely utilized for augmentation of bone fractures and fixation of orthopedic implants. These cements typically have an abundance of beneficial qualities, however their lack of bioactivity allows for continued development. To enhance osseointegration and bioactivity, calcium phosphate cements prepared with hydroxyapatite, brushite or tricalcium phosphates have been introduced with rather unsuccessful results due to increased cement viscosity, poor handling and reduced mechanical performance. This has limited the use of such cements in applications requiring delivery through small cannulas and in load bearing. The goal of this study is to design an alternative cement system that can better accommodate calcium-phosphate additives while preserving cement rheological properties and performance. In the present work, a number of brushite-filled two-solution bone cements were prepared and characterized by studying their complex viscosity-versus-test frequency, extrusion stress, clumping tendency during injection through a syringe, extent of fill of a machined void in cortical bone analog specimens, and compressive strength. The addition of brushite into the two-solution cement formulations investigated did not affect the pseudoplastic behavior and handling properties of the materials as demonstrated by rheological experiments. Extrusion stress was observed to vary with brushite concentration with values lower or in the range of control PMMA-based cements. The materials were observed to completely fill pre-formed voids in bone analog specimens. Cement compressive strength was observed to decrease with increasing concentration of fillers; however, the materials exhibited high enough strength for consideration in load bearing applications. The results indicated that partially substituting the PMMA phase of the two-solution cement with brushite at a 40% by mass concentration provided the best combination of the properties investigated. This alternative material may find applications in systems requiring highly injectable and viscous cements such as in the treatment of spinal fractures and bone defects.     

Mechanical Properties and Cytocompatibility Improvement of Vertebroplasty PMMA Bone Cements by Incorporating Mineralized Collagen

Polymethyl methacrylate (PMMA) bone cement is a commonly used bone adhesive and filling material in percutaneous vertebroplasty and percutaneous kyphoplasty surgeries. However, PMMA bone cements have been reported to cause some severe complications, such as secondary fracture of adjacent vertebral bodies, and loosening or even dislodgement of the set PMMA bone cement, due to the over-high elastic modulus and poor osteointegration ability of the PMMA. In this study, mineralized collagen (MC) with biomimetic microstructure and good osteogenic activity was added to commercially available PMMA bone cement products, in order to improve both the mechanical properties and the cytocompatibility. As the compressive strength of the modified bone cements remained well, the compressive elastic modulus could be significantly down-regulated by the MC, so as to reduce the pressure on the adjacent vertebral bodies. Meanwhile, the adhesion and proliferation of pre-osteoblasts on the modified bone cements were improved compared with cells on those unmodified, such result is beneficial for a good osteointegration formation between the bone cement and the host bone tissue in clinical applications. Moreover, the modification of the PMMA bone cements by adding MC did not significantly influence the injectability and processing times of the cement.     

Prolonged Post-Polymerization Biocompatibility of Polymethylmethacrylate-Tri-n-Butylborane (PMMA-TBB) Bone Cement

Polymethylmethacrylate (PMMA)-based acrylic bone cement is commonly used to fix bone and metallic implants in orthopedic procedures. The polymerization initiator tri-n-butylborane (TBB) has been reported to significantly reduce the cytotoxicity of PMMA-based bone cement compared to benzoyl peroxide (BPO). However, it is unknown whether this benefit is temporary or long-lasting, which is important to establish given that bone cement is expected to remain in situ permanently. Here, we compared the biocompatibility of PMMA-TBB and PMMA-BPO bone cements over several days. Rat femur-derived osteoblasts were seeded onto two commercially-available PMMA-BPO bone cements and experimental PMMA-TBB polymerized for one day, three days, or seven days. Significantly more cells attached to PMMA-TBB bone cement during the initial stages of culture than on both PMMA-BPO cements, regardless of the age of the materials. Proliferative activity and differentiation markers including alkaline phosphatase production, calcium deposition, and osteogenic gene expression were consistently and considerably higher in cells grown on PMMA-TBB than on PMMA-BPO, regardless of cement age. Although osteoblastic phenotypes were more favorable on older specimens for all three cement types, biocompatibility increased between three-day-old and seven-day-old PMMA-BPO specimens, and between one-day-old and three-day-old PMMA-TBB specimens. PMMA-BPO materials produced more free radicals than PMMA-TBB regardless of the age of the material. These data suggest that PMMA-TBB maintains superior biocompatibility over PMMA-BPO bone cements over prolonged periods of at least seven days post-polymerization. This superior biocompatibility can be ascribed to both low baseline cytotoxicity and a further rapid reduction in cytotoxicity, representing a new biological advantage of PMMA-TBB as a novel bone cement material.     

Influence of Natural Polysaccharides on Properties of the Biomicroconcrete-Type Bioceramics

In this paper, novel hybrid biomicroconcrete-type composites were developed and investigated. The solid phase of materials consisted of a highly reactive α -tricalcium phosphate (α-TCP) powder, hybrid hydroxyapatite-chitosan (HAp-CTS) material in the form of powder and granules (as aggregates), and the polysaccharides sodium alginate (SA) or hydroxypropyl methylcellulose (HPMC). The liquid/gel phase in the studied materials constituted a citrus pectin gel. The influence of SA or HPMC on the setting reaction, microstructure, mechanical as well as biological properties of biomicroconcretes was investigated. Studies revealed that manufactured cement pastes were characterized by high plasticity and cohesion. The dual setting system of developed biomicroconcretes, achieved through α-TCP setting reaction and polymer crosslinking, resulted in a higher compressive strength. Material with the highest content of sodium alginate possessed the highest mechanical strength (~17 MPa), whereas the addition of hydroxypropyl methylcellulose led to a subtle compressive strength decrease. The obtained biomicroconcretes were chemically stable and characterized by a high bioactive potential. The novel biomaterials with favorable physicochemical and biological properties can be prosperous materials for filling bone tissue defects of any shape and size.     

Characterization of Properties,In Vitro and In Vivo Evaluation of Calcium Phosphate/Amino Acid Cements for Treatment of Osteochondral Defects

Novel calcium phosphate cements containing a mixture of four amino acids, glycine, proline, hydroxyproline and either lysine or arginine (CAL, CAK) were characterized and used for treatment of artificial osteochondral defects in knee. It was hypothesized that an enhanced concentration of extracellular collagen amino acids (in complex mixture), in connection with bone cement in defect sites, would support the healing of osteochondral defects with successful formation of hyaline cartilage and subchondral bone. Calcium phosphate cement mixtures were prepared by in situ reaction in a planetary ball mill at aseptic conditions and characterized. It was verified that about 30–60% of amino acids remained adsorbed on hydroxyapatite particles in cements and the addition of amino acids caused around 60% reduction in compressive strength and refinement of hydroxyapatite particles in their microstructure. The significant over-expression of osteogenic genes after the culture of osteoblasts was demonstrated in the cement extracts containing lysine and compared with other cements. The cement pastes were inserted into artificial osteochondral defects in the medial femoral condyle of pigs and, after 3 months post-surgery, tissues were analyzed macroscopically, histologically, immunohistochemically using MRI and X-ray methods. Analysis clearly showed the excellent healing process of artificial osteochondral defects in pigs after treatment with CAL and CAK cements without any inflammation, as well as formation of subchondral bone and hyaline cartilage morphologically and structurally identical to the original tissues. Good integration of the hyaline neocartilage with the surrounding tissue, as well as perfect interconnection between the neocartilage and new subchondral bone tissue, was demonstrated. Tissues were stable after 12 months’ healing.     

Development and Analysis of a Hydroxyapatite Supplemented Calcium Silicate Cement for Endodontic Treatment

Aim: To develop an endodontic cement using bovine bone-derived hydroxyapatite (BHA), Portland cement (PC), and a radiopacifier. Methods: BHA was manufactured from waste bovine bone and milled to form a powder. The cements were developed by the addition of BHA (10%/20%/30%/40% wt), 35% wt, zirconium oxide (radiopacifier) to Portland cement (PC). A 10% nanohydroxyapatite (NHA) cement containing PC and a radiopacifier, and a cement containing PC (PC65) and a radiopacifier were also manufactured as controls. The cements were characterised to evaluate their compressive strength, setting time, radiopacity, solubility, and pH. The biocompatibility was assessed using Saos-2 cells where ProRoot MTA acted as the control. Compressive strength, solubility and pH were evaluated over a 4-week curing period. Results: The compressive strength (CS) of all cements increased with the extended curing times, with a significant CS increase in all groups from day 1 to day 28. The BHA 10% exhibited significantly higher CS compared with the other cements at all time points investigated. The BHA 10% and 20% groups exhibited significantly longer setting times than BHA 30%, 40% and PC65. The addition of ZrO₂ in concentrations above 20% wt and Ta₂O₅ at 30% wt resulted in a radiopacity equal to, or exceeding that of, ProRoot MTA. The experimental cements exhibited relatively low cytotoxicity, solubility and an alkaline pH. Conclusions: The addition of 10% and 20% BHA to an experimental PC-based cement containing 35% ZrO₂ improved the material’s mechanical strength while enabling similar radiopacity and biocompatibility to ProRoot MTA. Although BHA is a cost-effective, biomimetic additive that can improve the properties of calcium silicate endodontic cements, further studies are now warranted to determine its clinical potential.     

Tetracalcium Phosphate/Monetite/Calcium Sulfate Hemihdrate Biocement Powder Mixtures Prepared by the One-Step Synthesis for Preparation of Nanocrystalline Hydroxyapatite Biocement-Properties and In Vitro Evaluation

A modified one-step process was used to prepare tetracalcium phosphate/monetite/calcium sulfate hemihydrate powder cement mixtures (CAS). The procedure allowed the formation of monetite and calcium sulfate hemihydrate (CSH) in the form of nanoparticles. It was hypothesized that the presence of nanoCSH in small amounts enhances the in vitro bioactivity of CAS cement in relation to osteogenic gene markers in mesenchymal stem cells (MSCs). The CAS powder mixtures with 15 and 5 wt.% CSH were prepared by milling powder tetracalcium phosphate in an ethanolic solution of both orthophosphoric and sulfuric acids. The CAS cements had short setting times (around 5 min). The fast setting of the cement samples after the addition of the liquid component (water solution of NaH₂PO₄) was due to the partial formation of calcium sulfate dihydrate and hydroxyapatite before soaking in SBF with a small change in the original phase composition in cement powder samples after milling. Nanocrystalline hydroxyapatite biocement was produced by soaking of cement samples after setting in simulated body fluid (SBF). The fast release of calcium ions from CAS5 cement, as well as a small rise in the pH of SBF during soaking, were demonstrated. After soaking in SBF for 7 days, the final product of the cement transformation was nanocrystalline hydroxyapatite. The compressive strength of the cement samples (up to 30 MPa) after soaking in simulated body fluid (SBF) was comparable to that of bone. Real time polymerase chain reaction (RT-PCR) analysis revealed statistically significant higher gene expressions of alkaline phosphatase (ALP), osteonectin (ON) and osteopontin (OP) in cells cultured for 14 days in CAS5 extract compared to CSH-free cement. The addition of a small amount of nanoCSH (5 wt.%) to the tetracalcium phosphate (TTCP)/monetite cement mixture significantly promoted the over expression of osteogenic markers in MSCs. The prepared CAS powder mixture with its enhanced bioactivity can be used for bone defect treatment and has good potential for bone healing.