Biocompatibility In-vitro of Gel/HA Composite Scaffolds Containing Nano-Bioactive Glass for Tissue Engineering

Designing and fabricating nanocomposite scaffolds for bone regeneration from different biodegradable polymers and bioactive materials are an essential step to engineer tissues. In this study, the composite scaffold of gelatin/hyaluronic acid (Gel/HA) containing nano-bioactive glass (NBG) was prepared by using freeze-drying method. The biocompatibilities in-vitro of the Gel-HA/NBG composite scaffolds, including MTT assay, ALP activity, von Kossa staining and tetracycline staining, were investigated. The SEM observations revealed that the prepared scaffolds were porous with three-dimensional (3D) and interconnected microstructure, agglomerated NBG particles were uniformly dispersed in the matrix. MTT results indicated that the tested materials didn't show any cytotoxicity. The presence of NBG in the composite scaffold further enhanced the ALP activity in comparison with the pure Gel/HA scaffold. The von Kossa staining and tetracycline staining results also indicated that the NBG may improve the cell response. Therefore, the results indicated the nanocomposite scaffold made from Gel, HA and NBG particles could be considered as a potential bone tissue engineering implant.     

纳米羟基磷灰石/丝素蛋白复合支架材料的降解特性及生物相容性研究

应用共混法制备了纳米羟基磷灰石/丝素蛋白复合支架材料, 通过体外降解和细胞培养实验研究了复合支架材料的降解特性和生物相容性. 体外降解实验结果显示, 复合支架材料具有稳定的降解能力; 在降解过程中, 羟基磷灰石由于与降解液发生钙、磷等离子的交换, 使其结晶得到了进一步生长和完善. 利用细胞计数法、四甲基偶氮唑盐(MTT)比色法和碱性磷酸酶(ALP)活性测定等分析了复合支架材料的生物相容性, 结果表明, MG63细胞在复合支架材料上具有良好的粘附、增殖能力, 并可引起早期的骨分化. 因此, 纳米羟基磷灰石/丝素蛋白复合支架作为骨组织工程的支架材料具有良好的应用前景.     

低热-高压法制备PLGA多孔支架及其体外降解研究

采用低热-高压法制备了聚(dl-丙交酯／乙交酯)75／25(PLGA75／25)组织工程多孔支架。该方法避免了使用有机溶剂，支架的孔隙率在90％以上，孔径大小分布均匀。多孔支架经过酒精处理后，支架表面产生许多微小的凹陷；用藻酸钙改性处理后，支架形态保持良好。两种处理都使支架的压缩强度有所增大，亲水性增强。虽然孔隙率高的支架降解速率稍慢，但其体外降解规律基本一致：特性粘数争力学强度衰减快，而质量损失较慢，降解6周后，支架的质量损失仅为3％左右；体外降解3周后，支架的形态保持良好，可望在细胞移植争组织修复的早期发挥支撑作用。     

The Design of 3D-Printed Polylactic Acid–Bioglass Composite Scaffold: A Potential Implant Material for Bone Tissue Engineering

Bio-based and patient-specific three-dimensional (3D) scaffolds can present next generation strategies for bone tissue engineering (BTE) to treat critical bone size defects. In the present study, a composite filament of poly lactic acid (PLA) and 45S5 bioglass (BG) were used to 3D print scaffolds intended for bone tissue regeneration. The thermally induced phase separation (TIPS) technique was used to produce composite spheres that were extruded into a continuous filament to 3D print a variety of composite scaffolds. These scaffolds were analyzed for their macro- and microstructures, mechanical properties, in vitro cytotoxicity and in vivo biocompatibility. The results show that the BG particles were homogeneously distributed within the PLA matrix and contributed to an 80% increase in the mechanical strength of the scaffolds. The in vitro cytotoxicity analysis of PLA-BG scaffolds using L929 mouse fibroblast cells confirmed their biocompatibility. During the in vivo studies, the population of the cells showed an elevated level of macrophages and active fibroblasts that are involved in collagen extracellular matrix synthesis. This study demonstrates successful processing of PLA-BG 3D-printed composite scaffolds and their potential as an implant material with a tunable pore structure and mechanical properties for regenerative bone tissue engineering.     

Fabrication and Properties of Porous Collagen/Hyaluronic Composite Scaffolds Containing Nano-Bioactive Glass for Tissue Engineering

In this work, nano-structured scaffolds were designed for tissue engineering using collagen, hyaluronic acid (HA) and nano-bioactive glass (NBAG) as their main components. The scaffold was prepared via freeze-drying method and the properties including morphology, porosity, compressive strength, swelling ratio and cytotoxicity in-vitro, were also evaluated. The composite scaffolds showed well interconnected macropores with the pore size of ranging from 100 to 500 μm. The porosity percent and swelling ability were decreased with the introduction of NBAG into the collagen/HA hydrogel; however, the compressive strength was enhanced. The cytotoxicity in-vitro study shows that the collagen-HA/NBAG scaffolds have good biocompatibility with improving effect on fibroblastic cells growth. It could be concluded that this scaffold fulfills the main requirements to be considered as a bone substitute.     

Injectable Nanohybrid Scaffold for Biopharmaceuticals Delivery and Soft Tissue Engineering

An injectable nanofibrous hydrogel scaffold integrated with growth factors (GFs) loaded polysaccharide nanoparticles was developed that specifically allows for targeted adipose‐derived stem cells (ASCs) encapsulation and soft tissue engineering. The nanofibrous hydrogel was produced via biological conjugation of biotin‐terminated star‐shaped poly(ethylene glycol) (PEG‐Biotin) and streptavidin‐functionalized hyaluronic acid (HA‐Streptavidin). The polysaccharide nanoparticles were noncovalently assembled via electrostatic interactions between low‐molecular‐weight heparin (LMWH) and N,N,N‐trimethylchitosan chloride (TMC). Vascular endothelial growth factor (VEGF) was entrapped in the LMWH/TMC nanoparticles by affinity interactions with LMWH.     

Evaluation of Chitosan/Biphasic Calcium Phosphate Scaffolds for Maxillofacial Bone Tissue Engineering

Porous, 3D chitosan/biphasic calcium phosphate (BCP) scaffolds were used to prepare tissue engineering constructs for maxillofacial bone tissue reconstruction. Mesenchymal stem cells (MSC's) were seeded and cultured on clinically relevant sized scaffolds. In vitro engineered constructs facilitated the healing of mandibular defects in pigs if accompanied with delivery of basic fibroblast growth factor (bFGF).     

3D Plotted PCL Scaffolds for Stem Cell Based Bone Tissue Engineering

The ability to control the architecture and strength of a bone tissue engineering scaffold is critical to achieve a harmony between the scaffold and the host tissue. Rapid prototyping (RP) technique is applied to tissue engineering to satisfy this need and to create a scaffold directly from the scanned and digitized image of the defect site. Design and construction of complex structures with different shapes and sizes, at micro and macro scale, with fully interconnected pore structure and appropriate mechanical properties are possible by using RP techniques. In this study, RP was used for the production of poly(ε-caprolactone) (PCL) scaffolds. Scaffolds with four different architectures were produced by using different configurations of the fibers (basic, basic-offset, crossed and crossed-offset) within the architecture of the scaffold. The structure of the prepared scaffolds were examined by scanning electron microscopy (SEM), porosity and its distribution were analyzed by micro-computed tomography (µ-CT), stiffness and modulus values were determined by dynamic mechanical analysis (DMA). It was observed that the scaffolds had very ordered structures with mean porosities about 60%, and having storage modulus values about 1 × 10⁷ Pa. These structures were then seeded with rat bone marrow origin mesenchymal stem cells (MSCs) in order to investigate the effect of scaffold structure on the cell behavior; the proliferation and differentiation of the cells on the scaffolds were studied. It was observed that cell proliferation was higher on offset scaffolds (262000 vs 235000 for basic, 287000 vs 222000 for crossed structure) and stainings for actin filaments of the cells reveal successful attachment and spreading at the surfaces of the fibers. Alkaline phosphatase (ALP) activity results were higher for the samples with lower cell proliferation, as expected. Highest MSC differentiation was observed for crossed scaffolds indicating the influence of scaffold structure on cellular activities.     

可注射性骨组织工程支架材料不饱和聚磷酸酯的合成

以富马酸、1,2-丙二醇和三氯氧磷为起始原料,合成了主链重复结构单元中含不饱和双键的聚磷酸酯.FTIR及NMR研究表明.不饱和聚磷酸酯(UPPE)主链结构中含有富马酸二(1,2-丙二醇)酯(BPGF)的三种异构体.利用GPC研究了反应时间对聚合反应的影响,结果表明,延长反应时间有利于提高分子量,聚合物趋向于单分散性.反应18 h后,聚合物重均分子量达到5 956 g/mol,分散度为1.12.通过测定UPPE与N-乙烯基吡咯烷酮(NVP)的交联温度曲线,确定交联反应最高温度为41.14-82.30℃,固化时间在1.95-10.28 m in之间.     

Fabrication and enhanced mechanical properties of porous PLA/PEG copolymer reinforced with bacterial cellulose nanofibers for soft tissue engineering applications

A new class of polylactic acid (PLA)/polyethylene glycol (PEG) copolymer reinforced with bacterial cellulose nanofibers (BC) was prepared using a solvent casting and particulate leaching methods. Four weight fractions of BC (1, 2.5, 5, and 10 wt%) were incorporated into copolymer via silane coupling agent. Mechanical properties were evaluated using response surface method (RSM) to optimize the impact of pore size, porosity, and BC contents. Compressive strength obtained for PLA/PEG-5 BC wt% was 9.8 MPa, which significantly dropped after developing a porous structure to 4.9 MPa. Nielson model was applied to investigate the BC stress concentration on the PLA/PEG. Likewise, krenche and Hapli-Tasi model were employed to investigate the BC nanofiber reinforcement and BC orientation into PLA/PEG chains. The optimal parameters of the experiment results found to be 5 wt% for BC, 230 μm for pore size, and 80% for porosity. Scanning electron microscopy (SEM) micrograph indicates that uniform pore size and regular pore shape were achieved after an addition of BC-5% into PLA/PEG. The weight loss of copolymer-BC with scaffolds enhanced to the double values, compared with PLA/PEG-BC % without scaffolds. Differential Scanning Calorimetric (DSC) results revealed that the BC nanofiber improved glass transition temperature (T_g) 57 °C, melting temperature (T_m) 171 °C, and crystallinity (χ %) 43% of PLA/PEG reinforced-BC-5%.     

组织工程细胞支架及其细胞亲和性改进研究进展

综述近年来组织工程中有关细胞在材料上粘附的机理研究并从生物学观点和材料观点来分析影响细胞亲和性的因素,介绍了目前研究中的改性生物医学材料细胞亲和性的研究方法,并对今后的研究提出了建议。     

Polysaccharides and Their Derivatives for Versatile Tissue Engineering Application

Research and development in the design, synthesis, modification, evaluation, and characterization of polysaccharide‐based bioactive polymeric materials for guiding and promoting new tissue in‐growth is reviewed. Emphasis is given in this interdisciplinary field of tissue engineering (TE) with particular reference to bone, cartilage, and skin TE. Current strategies in scaffold‐guided TE approaches using polymers of natural origin and their composites are elaborated. Innovative modification techniques in creating functional materials for advanced TE applications are presented. Challenges and possible solutions in the technological innovation in factor molecules incorporation and surface functionalization for improving the fabrication of biomaterials scaffolds for cost‐effective TE are also presented.

     

Production and characterization of elastomeric cardiac tissue-like patches for Myocardial Tissue Engineering

Cardiovascular disease remains the leading cause of death. Damaged heart muscle is the etiology of heart failure. Heart failure is the most frequent cause of hospital and emergency room admissions. As a differentiated organ, current therapeutics and techniques can not repair or replace the damaged myocardial tissue. Myocardial tissue engineering is one of the promising treatment modalities for repairing damaged heart tissue in patients with heart failure. In this work, random Polylactic acid (PLA), Polylactic acid/Polyethylene glycol (PLA/PEG) and random and aligned Polylactic acid/Polyethylene glycol/Collagen (PLA/PEG/COL) nanofiber patches were successfully produced by the electrospinning technique. In vitro cytotoxic test (MTT), morphological (SEM), molecular interactions between the components (FT-IR), thermal analysis (DSC), tensile strength and physical analysis were carried out after production. The resulting nanofiber patches exhibited beadless and smooth structures. When the fiber diameters were examined, it was observed that the collagen doped random nanofiber patches had the lowest fiber diameter value (755 nm). Mechanical characterization results showed that aligned nanofiber patches had maximum tensile strength (5.90 MPa) values compared to PLA, PLA/PEG, and PLA/PEG/COL (random). In vitro degradation test reported that aligned patch had the highest degradation ratio. The produced patches displayed good alignment with tissue on cardiomyocyte cell morphology studies. In conclusion, newly produced patches have noticeable potential as a tissue-like cardiac patch for regeneration efforts after myocardial infarction.     

组分对含羟基磷灰石/脂肪族聚氨酯复合骨组织工程支架的理化性能及生物学性能的影响

以异佛尔酮二异氰酸酯为聚氨酯硬段,通过原位聚合使聚合过程中释放的气体发泡,制备了用作骨组织工程材料的羟基磷灰石/脂肪族聚氨酯多孔支架.系统考察了不同组成配方,即羟基磷灰石(HA)含量、发泡剂含量以及聚氨酯(PU)软硬段的比例对三维支架材料的机械性能和微观孔隙结构等的影响,并通过体外细胞培养和体内肌肉植入初步评价了该复合...     

电活性和生物活性多巴-胰岛素样生长因子-1@聚(乙交酯-丙交酯)/聚(3-己基噻吩)静电纺丝纤维的制备及神经组织工程应用

理想型神经修复材料应具备与正常神经相似的导电性、仿生细胞外基质结构以及释放特定的生长因子等性能。 本研究将不同质量分数(0、3%、5%、10%)的聚(3-己基噻吩)(P3HT)加入到聚(乙交酯-丙交酯)(PLGA)中,采用静电纺丝工艺,制备了具有电活性和仿生结构的复合纤维。 利用酪氨酸羟化酶,将不同质量浓度(10、50、100 ng/mL)的含多巴接头的胰岛素样生长因子-1(DOPA-IGF-1)绑定在纤维表面,实现生长因子长效稳定的作用。 通过扫描电子显微镜、接触角表征了纤维直径、分布以及表面亲疏水性。 利用细胞培养、荧光染色实验评估了纤维在体外的生物相容性和生物活性。 结果表明,该电活性纤维能有效促进大鼠肾上腺嗜铬细胞瘤细胞(PC12)增殖,其中,PLGA/P3HT-5%纤维表现出更好的细胞响应性。 结合DOPA-IGF-1质量浓度为10 ng/mL的纤维更利于PC12细胞的黏附、生长。 兼具电活性和生物活性的纳米纤维DOPA-IGF-1@PLGA/P3HT在神经组织修复领域具有潜在的应用价值。     

用高度取向石墨烯/聚乳酸(Gr/PLLA)复合超细纤维构建神经导管

制备了一种高度取向的石墨烯(Gr)/聚乳酸(PLLA)复合超细纤维,并构建了神经导管,研究了Gr/PLLA促进神经细胞生长与分化的协同诱导作用.研究结果表明,Gr/PLLA具有较好的纤维形貌与取向度;Gr的引入提高了纤维的热性能及力学性能;Gr加入量(≤1%)的增加及纤维取向度的提高使雪旺细胞(SCs)的黏附数量及伸展比例均呈增加趋势;Gr/PLLA纤维可促进SCs的增殖,雪旺细胞在96 h时达到最佳生长状态,表明Gr/PLLA纤维具有较好的细胞相容性.基于细胞形貌及轴突数量统计发现,Gr/PLLA纤维也能促进大鼠肾上腺嗜铬细胞瘤(PC12细胞)的神经分化.直径为2 mm的Gr/PLLA纤维导管具有较好的纤维取向度和抗压能力,能促进细胞沿管轴方向取向生长.     

Natural and Synthetic Polymer Scaffolds Comprising Upconversion Nanoparticles as a Bioimaging Platform for Tissue Engineering

Modern biocompatible materials of both natural and synthetic origin, in combination with advanced techniques for their processing and functionalization, provide the basis for tissue engineering constructs (TECs) for the effective replacement of specific body defects and guided tissue regeneration. Here we describe TECs fabricated using electrospinning and 3D printing techniques on a base of synthetic (polylactic-co-glycolic acids, PLGA) and natural (collagen, COL, and hyaluronic acid, HA) polymers impregnated with core/shell β-NaYF₄:Yb³⁺,Er³⁺/NaYF₄ upconversion nanoparticles (UCNPs) for in vitro control of the tissue/scaffold interaction. Polymeric structures impregnated with core/shell β-NaYF₄:Yb³⁺,Er³⁺/NaYF₄ nanoparticles were visualized with high optical contrast using laser irradiation at 976 nm. We found that the photoluminescence spectra of impregnated scaffolds differ from the spectrum of free UCNPs that could be used to control the scaffold microenvironment, polymer biodegradation, and cargo release. We proved the absence of UCNP-impregnated scaffold cytotoxicity and demonstrated their high efficiency for cell attachment, proliferation, and colonization. We also modified the COL-based scaffold fabrication technology to increase their tensile strength and structural stability within the living body. The proposed approach is a technological platform for “smart scaffold” development and fabrication based on bioresorbable polymer structures impregnated with UCNPs, providing the desired photoluminescent, biochemical, and mechanical properties for intravital visualization and monitoring of their behavior and tissue/scaffold interaction in real time.