冰微粒致孔制备聚羟基丁酸酯(PHB)多孔支架

目的以冰粒子为致孔剂,用粒子滤出—冷冻干燥复合工艺制备PHB多孔支架。方法本实验以氯仿为溶剂,将PHB溶液浇入预先排列好的冰微粒空隙中,采用真空渗流方法制备冰微料-PHB复合体,液氮冷却成型后,用粒子滤出—冷冻干燥复合工艺制备多孔支架。通过扫描电镜(SEM)观测,研究该制备工艺对支架形貌的影响。结果制备的块状三维多孔支架孔径可调、孔隙结构良好、孔隙连通度高。结论本文工艺所制备的多孔支架无致孔剂残留,孔隙率高,孔隙连通度高,制备过程不会损害材料的生物相容性,可安全地用于组织工程可降解聚合物多孔支架的制备。     

胎儿骨髓间充质干细胞复合PLGA支架的形态学观察

目的 探讨胎儿骨髓间充质干细胞(fetal bone marrow mesenehymal stem cells，fBMSCs)与低热高压法制作的聚丙交酯-乙交酯(PLGA)支架材料复合培养。构建组织工程化骨的可行性。方法 预制PLGA支架材料，取5月胎儿肱骨和股骨骨髓，用单核细胞分离液分离fBMSCs，含双抗的低糖DMEM原代和传代培养，倒置显微镜下观察细胞生物学特性，用F1TC标记的抗CDl05、CD44和用PE标记的抗CD34、CD29对第4代细胞进行流式细胞鉴定，并与PLGA支架材料复合培养l周后行扫描电镜观察。结果原代及传代培养的fBMSCs增殖较迅速，第4代CD105阳性细胞占84．08％，CD29阳性细胞占88．77％，CD44阳性细胞占89．53％。复合PLGA支架材料细胞生长状态良好。结论 骨髓间充质干细胞(bone mesenchymal stem cells，BMSCs)是骨组织工程适宜的种子细胞，与低热高压制作的PLGA支架材料复合可体外构建组织工程骨。     

组织工程心脏瓣膜研究进展

目前组织工程心脏瓣膜研究已在支架的选材、种子细胞的选择、种子细胞的种植与瓣膜构建方法三个方面取得进展，并已构建出三种代表性组织工程心脏瓣膜。对它们各自的特点进行综述。     

基于选区激光熔融技术制备的多孔钛合金支架的力学性能及成骨能力评价

目的评价选区激光熔融(selective laser melting,SLM)技术制备的多孔钛合金支架的力学性能及成骨能力。方法通过SLM技术制备两种多孔钛合金(Ti6-Al4-V)支架,分别为均一多孔组和复合多孔组,简称均一组与复合组,并对其力学性能、体外细胞相容性和体内骨整合能力进行评价。结果与传统锻件相比,多孔钛合金支架的弹性模量更接近人体正常骨组织,且复合组的弹性模量高于均一组,差异具有统计学意义(0.05)。细胞相容性方面,随着时间的推移,间充质干细胞数量在两组多孔支架上均有增加,但复合组钛合金支架在5 d和7 d的细胞数量高于均一组(0.05)。该组在成骨分化实验的7 d也具有更高的ALP活性(0.05)。诱导14 d后两组ALP活性无差异。体内植入实验表明,3个月时,复合组的骨体积分数与均一组比较差异无统计学意义(0.05)。结论本研究表明,基于SLM制备的多孔钛合金支架弹性模量适宜,具有骨整合能力,适合做骨缺损修复材料。     

组织工程用聚合物多孔支架的制备技术

组织工程用多孔支架不仅要有普通生物材料具有的性能,而且对其孔径、孔隙率、比表面积等物理性能也有一定的要求,而这些物理性能与多孔支架的制备工艺密切相关。本文对组织工程用聚合物多孔支架的制备方法进行了较为全面的回顾,包括纤维粘结法、粒子致孔法、熔融成型法、气体发泡法、相分离法、烧结微球法和快速成型等方法。每种方法各有其优缺点,将多种方法结合,制备出同时具有复杂外形和规则的相连孔结构是组织工程多孔支架制备技术研发的方向。     

Comparison of adipose stem cells sources from various locations of rat body for their application for seeding on polymer scaffolds

Adipose tissue yields adult adipose stem cells (ASCs) in large quantities via less-invasive methods. These cells are of interest owing to their modulating properties and paracrine activities, which can be harnessed in regenerative medicine. Many studies on the use of rat fat tissue in an autologous animal model have been conducted; however, the different locations to obtain stromal vascular fraction of rat fat depots have not been fully characterized. The purpose of the current study was to identify optimal source of ASC from various locations of rat body. Animal experiments in vitro revealed that fat depots from cervical fat are an optimal ASC source. A high ASC yield facilitates subsequent studies on autologous transplantation in rats. The secondary objective was to compare the efficiency of osteoinductive media composition and evaluate of osteogenic potential of ASCs for seeding on scaffolds for bone repair. Scaffolds were assessed in vitro, using rat adipose stem cells and three-dimensional (3D) scaffolds comprising polycaprolactone (PCL) or polycaprolactone covered with tricalcium phosphate (PCL + 5%TCP). Seeded ASCs adhere to the surface and migrate to the scaffolds. Upon staining and determining alkaline phosphatase levels, PCL + 5%TCP scaffolds performed better than PCL scaffolds. Furthermore, growth factors such as BMP2 and FGF2 significantly increased ASC mineralization and induced osteogenesis (p?<?0.05). Our results may help select and develop pre-clinical animal model for confirming the use of ASC, alone or in association with appropriate biomaterials for bone repair.     

Melt-spun shaped fibers with enhanced surface effects: Fiber fabrication,characterization and application to woven scaffolds

Scaffolds with a high surface-area-to-volume ratio (SA:V) are advantageous with regard to the attachment and proliferation of cells in the field of tissue engineering. This paper reports on the development of novel melt-spun fibers with a high SA:V, which enhanced the surface effects of a fiber-based scaffold while maintaining its mechanical strength. The cross-section of the fibers was altered to a non-circular shape, producing a higher SA:V for a similar cross-sectional area. To obtain fibers with non-circular cross-sectional shape, or shaped fibers, three different types of metal spinnerets were fabricated for the melt-spinning process, each with circular, triangular or cruciform capillaries, using deep X-ray lithography followed by nickel electroforming. Using these spinnerets, circular and shaped fibers were manufactured with biodegradable polyester, polycaprolactone. The SA:V increase in the shaped fibers was experimentally investigated under different processing conditions. Tensile tests on the fibers and indentation tests on the woven fiber scaffolds were performed. The tested fibers and scaffolds exhibited similar mechanical characteristics, due to the similar cross-sectional area of the fibers. The degradation of the shaped fibers was notably faster than that of circular fibers, because of the enlarged surface area of the shaped fibers. The woven scaffolds composed of the shaped fibers significantly increased the proliferation of human osteosarcoma MG63 cells. This approach to increase the SA:V in shaped fibers could be useful for the fabrication of programmable, biodegradable fiber-based scaffolds in tissue engineering.     

Engineering strategies to control vascular endothelial growth factor stability and levels in a collagen matrix for angiogenesis: The role of heparin sodium salt and the PLGA-based microsphere approach

New vessel formation is the result of the complex orchestration of various elements, such as cells, signalling molecules and extracellular matrix (ECM). In order to establish the suitable conditions for an effective cell response, the influence of vascular endothelial growth factor (VEGF) complexation with heparin sodium salt (Hp) on its pro-angiogenic activity has been evaluated by an in vitro capillary-like tube formation assay. VEGF with or without Hp was embedded into collagen gels, and the activated matrices were characterized in terms of VEGF activity and release kinetics. Taking into account the crucial role of Hp in VEGF stability and activity, VEGF/Hp complex was then encapsulated into microspheres based on poly(lactide-co-glycolide) (PLGA), and microsphere properties, VEGF/Hp release kinetics and VEGF in vitro activity over time were evaluated. Integrated microsphere/collagen matrices were developed in order to provide a continuous release of active VEGF/Hp inside the matrix but also a VEGF gradient at the boundary, which is an essential condition for endothelial cell attraction and scaffold invasion. The results confirmed a strong influence of Hp on VEGF configuration and, consequently, on its activity, while the encapsulation of VEGF/Hp complex in PLGA-microspheres guaranteed a sustained release of active VEGF for more than 30 days. This paper confirms the importance of VEGF stability and signal presentation to cells for an effective proangiogenic activity and highlights how the combination of two stabilizing approaches, namely VEGF/Hp complexation and entrapment within PLGA-based microspheres, may be a very effective strategy to achieve this goal.     

Balancing mechanical strength with bioactivity in chitosan–calcium phosphate 3D microsphere scaffolds for bone tissue engineering: air- vs. freeze-drying processes

The objective of this study was to evaluate the potential benefit of 3D composite scaffolds composed of chitosan and calcium phosphate for bone tissue engineering. Additionally, incorporation of mechanically weak lyophilized microspheres within those air-dried (AD) was considered for enhanced bioactivity. AD microsphere, alone, and air- and freeze-dried microsphere (FDAD) 3D scaffolds were evaluated in vitro using a 28-day osteogenic culture model with the Saos-2 cell line. Mechanical testing, quantitative microscopy, and lysozyme-driven enzymatic degradation of the scaffolds were also studied. FDAD scaffold showed a higher concentration (p?<?0.01) in cells per scaffold mass vs. AD constructs. Collagen was ～31% greater (p?<?0.01) on FDAD compared to AD scaffolds not evident in microscopy of microsphere surfaces. Alternatively, AD scaffolds demonstrated a superior threefold increase in compressive strength over FDAD (12 vs. 4?MPa) with minimal degradation. Inclusion of FD spheres within the FDAD scaffolds allowed increased cellular activity through improved seeding, proliferation, and extracellular matrix production (as collagen), although mechanical strength was sacrificed through introduction of the less stiff, porous FD spheres.     

In vitro development of engineered muscle using a scaffold based on the pressure‐activated microsyringe (PAM) technique

The development of new human skeletal muscle tissue is an alternative approach to the replacement of tissue after severe damage, for example in the case of traumatic injury, where surgical reconstruction is often needed following major loss of natural tissue. Treatment to date has involved the transfer of muscle tissue from other sites, resulting in a functional loss and volume deficiency of donor sites. Approaches that seek to eliminate these problems include the relatively new solution of skeletal muscle engineering. Here there are two main components to consider: (a) the cells with their regenerative potential; and (b) the polymeric structure onto which cells are seeded and where they must perform their activities. In this paper we describe well‐defined two‐ and three‐dimensional polymeric structures able to drive the myoblast process of adhesion, proliferation and differentiation. We examine a series of polymers and protein adhesions with which to functionalize the structures, and cell‐seeding methods, with a view to defining the optimal protocol for engineering skeletal muscle tissue. All polymer samples were tested for their mechanical and biological properties, to support the validity of our results in the real context of muscle tissue engineering. Copyright © 2014 John Wiley & Sons, Ltd.