Medpor in maxillofacial deformities: report of three cases

Objective  This paper deals with the usefulness and versatility of the porous high-density polyethylene implants for correction of various facial deformities as an augmentation and an onlay graft material with its advantages. Materials and methods  Prefabricated porous high-density polyethylene implants were used in three patients (post-trauma facial deformity, Goldenhar syndrome, nasal deformity in cleft patient) for secondary reconstruction of orbital floor, depressed nose and supra-orbital ridge, augmentation of hypoplastic mandible and depressed nasal dorsum under general anaesthesia. Results  Good esthetic results were achieved in all the three patients treated with porous high-density polyethylene implants with no complications. Conclusion  Porous high-density polyethylene alloplastic implant is an excellent biomaterial for reconstruction of various facial deformities with many advantages over autogenous and other alloplastic materials.     

Optimizing Delivery of Multivalent Targeting Constructs for Detection of Secondary Tumors

Targeting drugs or imaging molecules to specific cells by conjugating them to antibodies or ligands for cell surface receptors may allow earlier detection of pathology, better localization for intervention, and fewer side effects. Delivery of these molecules to the target is complicated by construct size, which cannot cross typical endothelial barriers such as the vascular wall, and lack of a priori knowledge of the location of secondary tumor sites to which the construct is targeted. Here we develop mathematical models for diffusive and convection-enhanced delivery of a trivalent construct. Results show that delivery of the construct to the tissue does not yield acceptable contrast or specificity; therefore, unbound construct must be removed from the area of interest by allowing diffusion out of the area or a follow-up injection of fluid containing no construct (e.g., saline). The need for this additional step requires weeks to months for diffusive delivery to yield acceptable contrast, but convection-enhanced delivery may be able to achieve acceptable contrast within several days. Thus, convection-enhanced delivery of multivalent constructs may provide a mechanism to locate secondary tumor sites without prior knowledge of their location which would greatly enhance the ability to detect and treat cancer.     

酶组织化学方法在HA/TCP体内外生物相容性评价中的初步应用

通过研究材料与细胞 /组织相互作用后胞内酶活性的变化与材料生物相容性之间的关系 ,探讨酶组织化学法应用于材料生物相容性评价的可行性。结果发现 ,与 HA/ TCP和钛合金复合培养的成骨细胞形态学上无明显差异。但 HA/ TCP与兔成骨细胞复合培养初期可导致细胞 NADH、SDH、L DH和 CCO酶活性的一过性下降 ,而钛合金对复合培养细胞的酶活性没有明显影响 ,提示 HA/ TCP材料溶出物对细胞有轻微的损伤。两种材料体内植入后引起的组织学变化过程相似 ,主要表现为损伤引起的急性炎症过程。酶组织化学检测发现 ,术后 10 d内植入体周围组织四种酶活性均明显下降 ,15 - 30 d内逐渐恢复正常。但 HA/ TCP组酶活性的恢复略滞后于钛合金组 ,也表明材料溶出物对细胞有一定损伤。体内外实验均发现酶学指标能更灵敏地反映材料对细胞的作用 ,酶组织化学法可望应用于材料生物相容性评价。     

羟基磷灰石/壳聚糖生物复合材料的制备研究进展

羟基磷灰石/壳聚糖复合材料因其生物相容性和合适的力学性能逐渐成为骨替代材料研究的热点。本文综述了羟基磷灰石/壳聚糖复合材料的研究现状,探讨了其特点、制备和性能。并在此基础上提出了此类材料今后的发展方向：三相复合材料和电、磁学性能的研究。     

壳聚糖/肝素层层自组装涂层与CD133^＋内皮祖细胞生物相容性的实验研究

目的研究壳聚糖/肝素层层自组装涂层对CD133＋内皮祖细胞的黏附、增殖相关基因表达的影响,并从分子生物学角度探讨其作为促内皮修复功能药物洗脱支架涂层材料的可行性。方法（1）分离人脐血单个核细胞,免疫磁珠分选CD133＋内皮祖细胞;（2）制备壳聚糖/肝素层层自组装涂层,1%明胶涂层以及玻璃对照皿,接种并培养分选所得内皮祖细胞;（3）免疫荧光鉴定内皮祖细胞;（4）抽提总RNA,RT-PCR法比较不同培养介质中细胞的eNOS、VE-cadherin、KDR、PECAM-1、Sirtuin-1、Thrombomodulin等基因的表达差异。结果（1）重力梯度离心及磁珠分选法所得CD133＋内皮祖细胞纯度较高（92.88%±0.51%（n=4）,在VEGF诱导下能较好的分化为内皮细胞;（2）eNOS、VE-cadherin、KDR、PECAM-1和Sirtuin-1在壳聚糖/肝素层层自组装涂层组表达丰度较玻璃对照组显著增高（P〈0.05）,与明胶组差异不明显,Thrombomodulin在壳聚糖涂层表达丰度较明胶组、玻璃组表达均增高（P〈0.05）结论壳聚糖涂层能促进内皮祖细胞的黏附、增殖,生物相容性好,为理想的生物材料。     

Formation of carbonate-apatite crystals after implantation of calcium phosphate ceramics

Summary The aims of this study were (1) to determine at the crystal level, the nonspecific biological fate of different types of calcium phosphate (Ca−P) ceramics after implantation in various sites (osseous and nonosseous) in animals and (2) to investigate the crystallographic association of newly formed apatitic crystals with the Ca−P ceramics. Noncommercial Ca−P ceramics identified by X-ray diffraction as calcium hydroxylapatite (HA), beta-tricalcium phosphate (β-TCP), and biphasic calcium phosphates (BCP) (consisting of β-TCP/HA=40/60) were implanted under the skin in connective tissue, in femoral lamellar cortical bone, articular spine bone, and cortical mandibular and mastoidal bones of animals (mice, rabbits, beagle dogs) for 3 weeks to 11 months. In humans, HA or β-TCP granules were used to fill periodontal pockets, and biposies of the implanted materials were recovered after 2 and 12 months. Results of this study demonstrated the following: (1) the presence of needle-like microcrystals (new crystals) associated with the Ca−P ceraiic macrocrystals in the microporous regions of the implants regardless of the sites of implantation (osseous or nonosseous), type of Ca−P ceramics (HA, β-TCP, BCP), type of species used (mice, rabbits, dogs, humans), or duration of implantation; (2) decrease in the area occupied by the ceramic crystals and the subsequent filling of the spaces between the ceramic crystals by the new crystals; (3) these new crystals were identified as apatite by electron diffraction and as carbonate-apatite by infrared absorption spectroscopy; (4) high resolution transmission electron microscopy (Hr TEM) revealed one family of apatite lattice fringes in the new crystals in continuity with the lattice planes of the HA of β-TCP ceramic crystals; (5) Hr TEM also demonstrated the presence of linear dislocations at the junction of the new apatite crystals and ceramic crystals. It is suggested that the formation of the CO₃ apatite crystals associated with the implanted Ca−P ceramic is due to dissolution/precipitation and secondary nucleation involving an epitatic growing process and not to an osteogenic property of the ceramic.     

可注射性生物材料构建同种异体工程化软骨

目的研究在有免疫力的动物体内应用生物材料聚氧化乙烯丙烯凝胶构建同种异体工程化软骨的可行性.方法无菌条件下取新生兔关节软骨,经II型胶原酶消化8～12小时后,将软骨细胞和生物材料复合成细胞浓度为5×107/ml的复合物并移植于兔皮下,并以边注射,边后退的方法做条索状注射,以了解可否形成预定棒状软骨.同时分别设立单独注射细胞和材料两个对照组.分别于4、6、8及12周取材行大体观察,石蜡切片HE染色、SafraninO染色、Masson's三色染色,了解软骨形成情况.结果2周后即可于皮下触及新生结节,4周后取材即有基质分泌及胶原形成.于6周左右软骨接近成熟,生物材料基本吸收.8周、12周软骨基本接近正常软骨.同时可以见到以注射的方式塑形而成的棒状软骨.实验中未见明显的免疫排斥反应.而对照组未见软骨形成.结论生物材料聚氧化乙烯丙烯凝胶具有良好的生物相容性、可降解性、无细胞毒,是较理想的组织工程生物材料;应用该实验方法可在有免疫力的动物体内形成同种异体工程化软骨,并可以通过注射的方法进行简单的塑形.     

Development of novel dental restorative composites with dibasic calcium phosphate loaded chitosan fillers

The incorporation of antimicrobial agents in restorative dental composites has the potential to slow the development of carious lesions.ObjectiveThe objectives of the present study were to develop experimental composite resins with chitosan or chitosan loaded with dibasic calcium phosphate anhydrous (DCPA) particles and to demonstrate their antimicrobial potential without loss of mechanical properties or biocompatibility.MethodsChitosan and chitosan/DCPA particles were synthetized by the electrospray method. Experimental composites were formulated by adding 0, 0.5, or 1.0 wt% particles into a resin matrix along with 60 wt% barium glass. The degree of conversion and mechanical properties were measured after 1 and 90 days of aging in water after photoactivation. Cytotoxicity and genotoxicity were evaluated using fibroblasts from dental pulp in conditioned medium. The antimicrobial activity against Streptococcus mutans was assessed by crystal violet biofilm assay.ResultsThe experimental restorative composites were not found to be cytotoxic or genotoxic, with cell viability of 93.1 ± 8.0% (p = 0.328) and 3.0 ± 0.8% micronucleus per group (p = 0.1078), respectively. The antimicrobial results showed that all composites with approximately 20% less biofilm (p < 0.001) relative to the control. No chitosan release was detected from the composites, suggesting direct contact of the bacteria with exposed chitosan particles on the surface was responsible for the observed antimicrobial effect. The addition of the chitosan and chitosan/DCPA submicrometer (<250 nm average diameter) particles to restorative composites did not change the degree of conversion, flexural strength, elastic modulus and fracture toughness compared to the control group after 90 days aging in water.SignificanceIt can be concluded that the addition of chitosan or chitosan/DCPA particles in the restorative composites induced antimicrobial activity without compromising the mechanical properties or biocompatibility of the composites.