3D打印胶原/羟基磷灰石支架对骨髓间充质干细胞成骨分化的作用研究

目的探讨3D打印胶原/羟基磷灰石支架对骨髓间充质干细胞成骨分化的作用。 方法分离SPF级雄性SD大鼠骨髓间充质干细胞,实验分为：对照组、浸提组、诱导组及浸提诱导组,MTT法检测对照组,浸提组的细胞增殖情况,对比分析各组细胞的碱性磷酸酶（ALP）活性,对各组细胞诱导培养17天后进行茜素红染色,观察钙结节染色情况。 结果MTT结果显示,浸提组与对照组在不同时间点的OD值比较,差异无统计学意义（P>0.05）,ALP活性结果显示,不同时间点各组与对照组相比,差异均有统计学意义（P<0.05）;不同时间点浸提诱导组与浸提组相比,差异均有统计学意义（P<0.05）;诱导组在48 h及72 h与浸提组相比,差异均有统计学意义（P<0.05）。茜素红染色结果显示,对照组细胞无钙结节点,浸提组及诱导组镜下肉眼可明显观察到红色区域染色,镜下观察可见钙结节点,浸提诱导组所产生的钙结节点的数量、大小以及染色的颜色深度均明显优于其他各组。 结论3D打印胶原/羟基磷灰石支架具有生物相容性好,可促进BMSCs向成骨分化,对细胞毒性低等特点,适宜用作骨缺损的治疗。     

The lamina push test: an alternative to the globe push test for identifying the medial orbit during endoscopic sinus surgery

Background

Aside from endoscopic and image guidance confirmation, the standard method of identifying the lamina involves the surgeon or an assistant applying gentle pressure on the globe externally. This globe push test requires the surgeon to remove one instrument from the endoscopic field or an assistant to press on the globe, and the test is most useful when either the periorbita or periorbital fat is exposed. We propose an alternative, equally accurate, and more efficient technique dubbed the lamina push test.

Methods

A blunt instrument is used to gently apply lateral pressure in the expected location of the medial orbital wall. If the lamina has been adequately skeletonized, the entire lamina will be seen to move as a unit. If residual ethmoid partitions are present, no movement or only localized movement is observed.

Results

Using the lamina push test, we have been able to safely identify the lamina papyracea in all patients undergoing endoscopic sinus surgery, without injury to the lamina or orbital contents. The use of direct pressure significantly increases the movement of an intact lamina.

Conclusion

The lamina push test is a safe and effective technique for identification of the medial orbital wall, confirmation of removal of all lateral ethmoid partitions, and verification of lamina integrity. It enables more consistent identification of an intact lamina, allows the surgeon to keep both instruments in the endonasal surgical field, and does not require an assistant.

     

Reducing the risk of cerebrospinal fluid rhinorrhea following translabyrinthine surgery of the posterior fossa

ObjectiveTo describe the procedure and results of an adapted closure and reconstruction technique for translabyrinthine surgery that focuses on identifying and managing potential pathways for CSF egress to the middle ear and Eustachian tube.MethodsRetrospective review of a cohort of translabyrinthine acoustic neuroma cases that were reconstructed using this technique.ResultsIn addition to meticulous packing of potential conduits using soft tissue, hydroxyapatite cement is used to seal opened air cell tracts prior to obliteration of the mastoid defect using adipose tissue. Early results of a small patient cohort using this technique are encouraging and there were no wound infections. There was a single case of CSF rhinorrhea associated with incomplete sealing of opened petrous apex cells, with no recurrence after appropriate implementation of the described protocol during revision surgery.ConclusionProactive management of potential conduits of CSF egress including opened air cell tracts has a high likelihood of reducing rates of rhinorrhea and need for revision surgery after the translabyrinthine approach to the posterior fossa.     

Hydroxyapatite nanorods loaded with parathyroid hormone (PTH) synergistically enhance the net formative effect of PTH anabolic therapy

Parathyroid hormone (PTH) has been a major contributor to the anabolic therapy for osteoporosis, but its delivery to bone without losing activity and avoiding adverse local effects remain a challenge. Being the natural component of bone, use of hydroxyapatite for this purpose brings a major breakthrough in synergistic anabolism. This study focuses on synthesis, characterization and evaluation of in vitro and in vivo efficacy of PTH (1-34) adsorbed hydroxyapatite nanocarrier for synergistic enhancement in the anabolic activity of PTH for bone regeneration. The negative zeta potential of this nanocarrier facilitated its affinity to the Ca²⁺ rich bone tissue and solubilization at low pH enhanced specific delivery of PTH to the resorption pits in osteoporotic bone. In this process, PTH retained its anabolic effect and at the same time an increase in bone mineral content indicated enhancement of the net formative effect of the PTH anabolic therapy.     

The promotion of osteointegration under diabetic conditions using chitosan/hydroxyapatite composite coating on porous titanium surfaces

Composited Chitosan/Hydroxyapatite (CS/HA) material coated on titanium surface (cTi) is a promising approach to produce biomaterials with better osseointegration capacity, but its bio-performance under diabetic conditions and the mechanisms involved remain elusive. We propose that the alterations in the Wnt/β-catenin pathway may play a role in mediating the improvement effect of cTi on diabetes-induced impaired implant osteointegration. To confirm the hypothesis, primary rat osteoblasts incubated on Ti and cTi were subjected to normal serum (NS), diabetic serum (DS), DS + Wnt3a (a specific Wnt agonist) and DS + Dkk1 (a specific Wnt antagonist) treatment. In vivo study was performed on diabetic sheep implanted with Ti or cTi into the bone defect on crista iliaca. Results showed that diabetes depressed osteoblast function evidenced by impaired cell adhesion and morphology, decreased cell proliferation and ALP activity, and higher apoptotic rate on Ti. Importantly, both cTi and Wnt3a treatment ameliorated osteoblastic dysfunction and apoptosis under diabetic condition. Implantation with cTi significantly improved osteointegration evidenced by Micro-CT and histological examinations compared with Ti. Moreover, the aforementioned promotive effects afforded by cTi were abolished by blocking Wnt pathway with Dkk1. Our study explicitly demonstrates that CS/HA composite material improves diabetes-induced impaired osteointegration of Ti via the reactivation of Wnt/β-catenin pathway and provides a target point for biomaterial modification to attain better clinical performance in diabetic patients.     

透明质酸/壳聚糖复合支架的制备及其力学性能评价

目的　模拟天然骨组织的结构和成分,寻找适合骨组织工程的新型支架材料。 方法 以透明质酸、壳聚糖为基质材料,在微酸性环境中以一定配比与氯化钙和磷酸二氢钠混合,冷冻干燥得到多孔复合支架材料。然后在乙醇/水/尿素环境中分别陈化0、2、4、8、12和24 h,以生成产物钙磷盐前驱体转变为羟基磷灰石,最终制备出一种深度矿化的透明质酸/壳聚糖复合支架。并通过SEM、EDS等对支架进行表征,研究支架的形貌、成分及力学强度等性能。 结果 SEM观察显示,支架材料具有比较均匀的多孔结构,孔径大小为100~200 μm。EDS结果表明,复合支架在一次冻干之后形成的是磷酸氢钙（DCPD）,随着陈化时间的延长,DCPD逐渐向羟基磷灰石（HAP）转化。而压缩强度则表明经过原位矿化的支架力学性能显著提高。 结论 通过该法得到的透明质酸/壳聚糖复合支架可作为骨组织工程的新型支架材料。     

Remineralization potential of fully demineralized dentin infiltrated with silica and hydroxyapatite nanoparticles

Objective

This study investigates the potential of a novel guided tissue regeneration strategy, using fully demineralized dentin infiltrated with silica and hydroxyapatite (HA) nanoparticles (NPs), to remineralize dentin collagen that is completely devoid of native hydroxyapatite.

Methods

Dentin blocks were fully demineralized with 4 N formic acid and subsequently infiltrated with silica and HA NPs. The remineralizing potential of infiltrated dentin was assessed following a twelve week exposure to an artificial saliva solution by means of TEM, EDS and micro-CT. Measurements were taken at baseline and repeated at regular intervals for the duration of the study to quantify the P and Ca levels, the mineral volume percentage and mineral separation of the infiltrated dentin specimens compared to sound dentin and non-infiltrated controls.

Results

Infiltration of demineralized dentin with nano-HA restored up to 55% of the P and Ca levels at baseline. A local increase in the concentration of calcium phosphate compounds over a period of twelve weeks resulted in a higher concentration in P and Ca levels within the infiltrated specimens when compared to the non-infiltrated controls. Remineralization of demineralized dentin with silica NPs by immersion in artificial saliva was the most effective strategy, restoring 20% of the P levels of sound dentin. Micro-CT data showed a 16% recovery of the mineral volume in dentin infiltrated with silica NPs and a significant decrease in the mineral separation to levels comparable to sound dentin.

Significance

Demineralized dentin infiltrated with silica NPs appears to encourage heterogeneous mineralization of the dentin collagen matrix following exposure to an artificial saliva solution.     

珊瑚骨粉复合组织补片进行拔牙位点保存的临床研究

目的探讨使用珊瑚骨粉复合组织补片进行拔牙位点保存的临床效果。方法选取自2012年12月至2014年2月期间在武警总医院口腔种植科门诊采用微创技术拔除磨牙的患者45例,试验组20例,拔牙窝内植入珊瑚骨粉,组织补片覆盖表面关闭拔牙窝;对照组25例,拔牙后常规处理。1、3、6个月复诊,观察拔牙窝愈合情况。拔牙前及拔牙6个月后进行口内取模灌注石膏模型并拍摄X线牙片,分别测量牙槽嵴的高度和宽度,使用配对t检验分别对两组拔牙前至6个月期间牙槽嵴高度、宽度的变化进行统计学分析,使用两独立样本的t检验进行两组间牙槽嵴高度、宽度变化的比较,P〈0.05为差异具有统计学意义。结果临床观察除有一例组织补片脱落外,试验组其他拔牙窝均愈合良好,牙槽骨丰满,牙龈色、形、质与邻牙协调;而对照组牙槽嵴吸收、萎缩,高度降低、宽度显著缩小。统计学分析试验组牙槽嵴高度和宽度的改变无显著的统计学差异（P〉0.05）;对照组的上述改变具有统计学差异（P〈0.05）。两组间牙槽嵴高度、宽度的变化相比,二者间的差异均具有统计学意义（P〈0.05）。结论珊瑚骨粉复合组织补片有效保存了进行种植牙修复所必需的骨量,是进行拔牙后位点保存术的合适材料。     

Substrate geometry directs the in vitro mineralization of calcium phosphate ceramics

Repetitive concavities on the surface of bone implants have recently been demonstrated to foster bone formation when implanted at ectopic locations in vivo. The current study aimed to evaluate the effect of surface concavities on the surface mineralization of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) ceramics in vitro. Hemispherical concavities with different diameters were prepared at the surface of HA and β-TCP sintered disks: 1.8 mm (large concavity), 0.8 mm (medium concavity) and 0.4 mm (small concavity). HA and β-TCP disks were sintered at 1100 or 1200 °C and soaked in simulated body fluid for 28 days at 37 °C; the mineralization process was followed by scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction and calcium quantification analyses. The results showed that massive mineralization occurred exclusively at the surface of HA disks treated at 1200 °C and that nucleation of large aggregates of calcium phosphate started specifically inside small concavities instead of on the planar surface of the disks. Regarding the effect of concavity diameter size on surface mineralization, it was observed that small concavities induce 124- and 10-fold increased mineralization compared to concavities of large or medium size, respectively. The results of this study demonstrated that (i) in vitro surface mineralization of calcium phosphate ceramics with surface concavities starts preferentially within the concavities and not on the planar surface, and (ii) concavity size is an effective parameter to control the spatial position and extent of mineralization in vitro.     

A novel injectable,cohesive and toughened Si-HPMC (silanized-hydroxypropyl methylcellulose) composite calcium phosphate cement for bone substitution

This study reports on the incorporation of the self-setting polysaccharide derivative hydrogel (silanized-hydroxypropyl methylcellulose, Si-HPMC) into the formulation of calcium phosphate cements (CPCs) to develop a novel injectable material for bone substitution. The effects of Si-HPMC on the handling properties (injectability, cohesion and setting time) and mechanical properties (Young’s modulus, fracture toughness, flexural and compressive strength) of CPCs were systematically studied. It was found that Si-HPMC could endow composite CPC pastes with an appealing rheological behavior at the early stage of setting, promoting its application in open bone cavities. Moreover, Si-HPMC gave the composite CPC good injectability and cohesion, and reduced the setting time. Si-HPMC increased the porosity of CPCs after hardening, especially the macroporosity as a result of entrapped air bubbles; however, it improved, rather than compromised, the mechanical properties of composite CPCs, which demonstrates a strong toughening and strengthening effect. In view of the above, the Si-HPMC composite CPC may be particularly promising as bone substitute material for clinic application.