Fabrication and Evaluation of Porous Keratin/chitosan (KCS) Scaffolds for Effectively Accelerating Wound Healing*

ObjectiveTo develop a dressing with desired antibacterial activity, good water maintaining ability and mechanical properties for wound healing and skin regeneration. MethodsThe chitosan with different concentrations were added in keratin solution to form porous keratin/chitosan (KCS) scaffolds. The morphological characteristics, chemical composition, wettability, porosity, swelling ratio and degradation of the scaffolds were evaluated. The antibacterial activity was tested by usingS. aureusandE. colisuspension for 2 h. And L929 fibroblast cells culture was used to evaluate the cytotoxicity of the KCS scaffolds. ResultsThe adding of chitosan could increase the hydrophobicity, decrease porosity, swelling ratio and degradation rate of the KCS porous scaffolds.Mechanical properties of KCS scaffolds could be enhanced and well adjusted by chitosan. KCS scaffolds could obviously decrease bacteria number.The proliferation of fibroblast cells in porous KCS patch increased firstly and then decreased with the increase of chitosan concentration. It was appropriate to add 400 μg/mL chitosan to form porous KCS scaffold for achieving best cell attachment and proliferation compared with other samples. ConclusionThe porous KCS scaffold may be used as implanted scaffold materials forpromoting wound healing and skinregeneration.     

羟基磷灰石／壳聚糖复合微球的制备及其生物学作用的体外研究

目的：通过探究羟基磷灰石（HAp）壳聚糖（CS）复合微球支架对骨髓间充质干细胞体外生物学行为的影响,评估其作为骨组织工程支架的可行性。方法纳米 HAp 和CS 复合物通过微流体技术自组装成微球支架,显微镜下形态学观察。将 P2代骨髓间充质干细胞（BMSCs）与微球行体外共培养,计算前6 h 黏附率。培养1、3、6、9 d,计算增殖率并用 GraphPad Prism 6软件对数据进行处理;行扫描电镜及共聚焦扫描式显微镜检测,观察细胞黏附及分布。将细胞微球复合物填入自制模具中培养14～21 d,进行形态观察。结果显微镜镜下微球为完整的圆形,大小一致。BMSCs 与微球体外培养6 h,黏附率达90％以上。6 d 时,BMSCs 的增殖率达到最高。扫描电镜结果显示微球上有大量 BMSCs 黏附定植并分泌大量胞外基质将微球连接成整体;共聚焦扫描式显微镜结果可见明显的细胞骨架微丝蛋白。细胞微球体外模具培养18 d 后,形成了结构完整的组织块。结论HAp-CS 微球是一种良好的促BMSCs 种子细胞黏附定植的支架材料,是促进细胞生长的有效支撑载体,与共培养细胞形成的复合组织块有望应用于体内动物实验修复标准缺损。     

体外和体内内皮化在胶原包埋羟基磷灰石涂层的人工机械瓣膜的实验研究

目的：通过体外内皮化和体内内皮化,探讨沉积胶原包埋羟基磷灰石（HA）涂层人工机械瓣膜的可行性及其在人工机械瓣膜支架体内的再细胞化能力。方法制备犬血管内皮细胞（VEC）悬液,接种在胶原包埋 HA 涂层人工机械瓣膜材料上,置培养箱内分组培养如下：①37℃孵箱中静态培养2周;②动态旋转培养装置中培养2周,比较两组 VEC 分泌一氧化氮（NO）、前列环素（PGI2）水平;再分别将人工机械瓣膜植入犬右心房,术后6周,取出部分材料,扫描电子显微镜（SEM）下观察 VEC 在 HA 材料上的附着情况,了解 HA支架材料在体内的再细胞化能力。结果与静态系统相比,人工机械瓣膜在动态旋转系统构建胶原包埋 HA 涂层 VEC分泌 NO 、PGI2水平显著升高（P ＜0．05）;在犬右心房人工机械瓣膜取出材料中,动态旋转系统构建胶原包埋 HA 涂层VEC 层均匀分布,并有心脏内皮细胞附着,而静态培养系统中 VEC 层分布不均匀,胶原包埋 HA 涂层有心脏血管内皮细胞附着,而单纯人工机械瓣薄膜表面出现较多的血栓形成。结论动态旋转系统中构建的组织工程化瓣膜模型中, VEC 可能成为组织工程化机械瓣膜材料;胶原包埋的 HA 涂层人工机械瓣膜有利于 VEC 的黏附和生长。     

Mechanical Properties of Different Nanopatterned TiO2 Substrates and Their Effect on Hydrothermally Synthesized Bioactive Hydroxyapatite Coatings

Nanotechnology is a very attractive tool for tailoring the surface of an orthopedic implant to optimize its interaction with the biological environment. Nanostructured interfaces are promising, especially for orthopedic applications. They can not only improve osseointegration between the implant and the living bone but also may be used as drug delivery platforms. The nanoporous structure can be used as a drug carrier to the surrounding tissue, with the intention to accelerate tissue–implant integration as well as to reduce and treat bacterial infections occurring after implantation. Titanium oxide nanotubes are promising for such applications; however, their brittle nature could be a significantly limiting factor. In this work, we modified the topography of commercially used titanium foil by the anodization process and hydrothermal treatment. As a result, we obtained a crystalline nanoporous u-shaped structure (US) of anodized titanium oxide with improved resistance to scratch compared to TiO₂ nanotubes. The US titanium substrate was successfully modified with hydroxyapatite coating and investigated for bioactivity. Results showed high bioactivity in simulated body fluid (SBF) after two weeks of incubation.     

Directing osteogenesis of stem cells with hydroxyapatite precipitated electrospun eri–tasar silk fibroin nanofibrous scaffold

Stimulating stem cell differentiation without growth factor supplement offers a potent and cost-effective scaffold for tissue regeneration. We hypothesise that surface precipitation of nano-hydroxyapatite (nHAp) over blends of non-mulberry silk fibroin with better hydrophilicity and RGD amino acid sequences can direct the stem cell towards osteogenesis. This report focuses on the fabrication of a blended eri–tasar silk fibroin nanofibrous scaffold (ET) followed by nHAp deposition by a surface precipitation (alternate soaking in calcium and phosphate solution) method. Morphology, hydrophilicity, composition, and the thermal and mechanical properties of ET/nHAp were examined by field emission scanning electron microscopy, TEM, FT-IR, X-ray diffraction, TGA and contact angle measurement and compared with ET. The composite scaffold demonstrated improved thermal stability and surface hydrophilicity with an increase in stiffness and elastic modulus (778?±?2.4?N/m and 13.1?±?0.36?MPa) as compared to ET (160.6?±?1.34?N/m and 8.3?±?0.4?MPa). Mineralisation studies revealed an enhanced and more uniform surface deposition of HAp-like crystals, while significant differences in cellular viability and attachment were observed through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and confocal microscopy study. The cell viability and expression of adhesion molecules (CD 44 and CD 29) are found to be optimum for subsequent stages of growth proliferation and differentiation. The rates of proliferation have been observed to decrease owing to the transition of MSC from a state of proliferation to a state of differentiation. The confirmation of improved osteogenic differentiation was finally verified through the alkaline phosphatase assay, pattern of gene expression related to osteogenic differentiation and morphological observations of differentiated cord blood human mesenchymal stem cells under fluorescence microscope. The results obtained showed the improved physicochemical and biological properties of the ET/nHAp scaffold for osteogenic differentiation without the addition of any growth factors.     

Porous polyethylene implant reconstruction of the orbit after resection of spheno-orbital meningiomas: A novel technique

Background

Spheno-orbital meningiomas (SOM) are complex tumors involving the middle cranial fossa and orbit. Following resection of these tumors, reconstruction of the orbit can be challenging. Inadequate reconstruction may lead to cosmetic deformities and functional complications.

Objective

The development of a technique for orbital reconstruction which is technically straightforward, cost-effective, with an excellent functional and cosmetic outcome.

Technique

Twelve patients with SOM each underwent a modified orbital-zygomatic craniotomy with osteotomies based on individual tumor location. After tumor resection, the lateral orbit and orbital roof, where necessary, were reconstructed using a 1 mm porous polyethylene sheet, customized to reconstruct the bony anatomy of the lateral and superior orbit and secured with 1.5 × 4 mm titanium screws into the orbital roof and rim.

Results

All patients demonstrated stabilization or improvement of vision and satisfactory cosmetic outcomes. One complication (surgical site infection) was noted. Follow-up imaging was obtained at regular intervals. The resection cavity was easily visualized without interference from the implant in each case. One patient developed tumor recurrence requiring re-operation 20 months after the initial procedure.

Conclusions

Use of a 1 mm porous polyethylene sheet for reconstruction of the lateral orbit offers an excellent functional and cosmetic outcome, does not interfere with postoperative imaging, is technically straightforward, and is cost-effective.     

组织工程骨修复兔下颌骨缺损的实验研究

目的:探讨以兔骨髓基质细胞(BMSCs)为种子细胞、纳米羟基磷灰石/胶原(nHAC)为支架材料、兔自体富血小板血浆(PRP)为生长因子,构建组织工程骨修复兔下颌骨缺损能力。方法:兔下颌骨体部15mm×15mm全层骨缺损分别采取:A组,组织工程骨;B组,自体髂骨;C组,单纯nHAC材料;D组,对照组修复。术后1、3、6个月行放射性核素骨检测、骨密度测定及组织学观察。结果:放射性核素骨检测:术后1、3个月,A、B组成骨代谢能力明显优于C、D组,术后6个月时,各组之间骨代谢能力无明显差异;骨密度测定:A、B、C组骨缺损区域骨密度逐渐增加明显高于D组,术后3个月A组、B组骨密度较C组明显提高;组织学检查:A组术后1个月可见小片状类骨质出现,nHAC开始降解,术后3个月时新生骨成大片状结构,术后6个月nHAC几乎全部降解,缺损由骨组织修复,其成骨量与B组无明显差异却明显大于C组,D组仅为纤维组织修复。结论:本实验构建的组织工程骨修复颌骨缺损能力与自体髂骨相似而强于单独使用nHAC,且nHAC材料于体内可完全降解,因此BMSCs与nHAC及自体PRP复合所构建的组织工程骨是一种良好的骨缺损替代材料。     

新型骨支架复合材料修复牙槽骨缺损研究

目的:探讨多孔聚丙烯晴基碳纤维/壳聚糖/双相磷酸钙/聚乳酸-羟基乙酸(PAN/CS/BCP/PLGA)复合支架对大白兔牙槽骨缺损的修复能力。方法:采用真空冷冻干燥技术制备多孔PAN/CS/BCP/PLGA复合支架。选取32只成年雄性新西兰大白兔,随机分为实验组和对照组,手术制备大小为10mm×10mm×10mm牙槽骨缺损区。实验组骨缺损区植入PAN/CS/BCP/PLGA复合支架,对照组植入CS/PLGA复合材料,术后2、4、8、12周分期取材,进行X线检查、组织学观察、扫描电镜(SEM)检测和成骨细胞计数分析。结果:术后12周实验组检测结果,X线观察:骨缺损区阻射影与自体骨相同。组织学观察:骨缺损区完全被新骨充填,且为较成熟的板层骨,与自体骨完全融合。SEM检测:骨-材料界面形成骨性结合,移植材料大部分降解,被成熟骨组织替代。成骨细胞计数分析:成骨细胞生长活跃,统计学有显著性差异。结论:多孔PAN/CS/BCP/PLGA复合支架具备良好的生物活性和生物可降解性,对骨缺损的修复能力要优于CS/PLGA复合材料,为其成为骨组织工程支架替代材料提供理论依据。