生物打印在肌肉骨骼界面重建中的应用

文题释义：生物打印：是一种能够在数字三维模型辅助下,根据增材制造原理定位装配生物材料或细胞单元,从而制备组织工程支架和组织器官等制品的一种新兴技术。 肌肉骨骼界面：是指肌肉骨骼系统中存在的一系列结构、功能和工程相似的部位,其通过肌肉和骨骼附着实现平滑连接,通常这些界面主要包括骨-肌腱、骨-韧带和骨-软骨等。其工作原理和潜在机制使它们成为组织的独特分支,其在细胞组分上显著不同,但在结构和功能上是一致的。 背景：肌肉骨骼损伤和退行性疾病的手术治疗常涉及肌肉骨骼界面的重建,而实现肌肉骨骼界面与周围宿主组织的生物整合的关键是制造具有精确结构和不同材料的替代物。生物打印技术获得的人工组织可与天然肌肉骨骼界面组织具有相似的物理结构和生物活性。 目的：介绍肌肉骨骼界面组织的结构和生物功能特性,以及生物打印技术在肌肉骨骼界面重建中的应用。 方法：由第一作者以“bioprinting, musculoskeletal interface,生物打印,肌肉骨骼界面”为关键词,检索2005至2019年期间PubMed、Web of Science、Springerlink、Medline、万方、CNKI数据库中的相关文献。初检文章201篇,筛选后对60篇文章进行分析。 结果与结论：理想的生物打印肌肉骨骼界面移植物必须结构上与原界面组织相对应,以维持体内多变的生物力学环境;其次,植入之后必须保持这些植入物的生物活性,以开始修复和替换缺陷区域的功能。生物打印技术的发展为解决肌肉骨骼界面的重建带来了希望,但其仍然存在许多挑战：仿生功能性界面结构机械性能的提高、多个仿生结构的整合、生物打印结构的血管化,以及对力学刺激在界面组织发育和再生中的作用缺乏深入的研究。对于未来界面组织工程的研究方向,可以预料的是将种子细胞、细胞因子和基因治疗,以及生物反应器纳入界面组织工程支架中的一大热点,为解决界面组织整合这一难题提供创新性的解决方案。 ORCID: 0000-0002-6668-5036(张君伟) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Engineering Structurally Organized Cartilage and Bone Tissues

The field of tissue engineering promises to deliver biological substitutes to repair or replace tissues in the body that have been injured or diseased. The clinical demand for musculoskeletal tissues is particularly high, especially for cartilage and bone defects. Although they are generally considered biologically simple structures, musculoskeletal tissues consist of highly organized three-dimensional networks of cells and matrix, giving rise to tissue structures with remarkable mechanical properties. Although the field of cartilage and bone tissue engineering has progressed significantly in recent years, the development of structurally ordered tissues has not been accomplished. More strategies are needed to ensure that the appropriate cell and matrix organization is being achieved in the engineered tissues. This review emphasizes how different cell types and scaffold designs can be used to modulate tissue properties and engineer more complex tissue structures, with emphasis on cartilage and bone tissues.     

The effect of ozone gas sterilization on the properties and cell compatibility of electrospun polycaprolactone scaffolds

The growing area of tissue engineering has the potential to alleviate the shortage of tissues and organs for transplantation, and electrospun biomaterial scaffolds are extremely promising devices for translating engineered tissues into a clinical setting. However, to be utilized in this capacity, these medical devices need to be sterile. Traditional methods of sterilization are not always suitable for biomaterials, especially as many commonly used biomedical polymers are sensitive to chemical-, thermal- or radiation-induced damage. Therefore, the objective of this study was to evaluate the suitability of ozone gas for sterilizing electrospun scaffolds of polycaprolactone (PCL), a polymer widely utilized in tissue engineering and regenerative medicine applications, by evaluating if scaffolds composed of either nanofibres or microfibres were differently affected by the sterilization method. The sterility, morphology, mechanical properties, physicochemical properties, and response of cells to nanofibrous and microfibrous PCL scaffolds were assessed after ozone gas sterilization. The sterilization process successfully sterilized the scaffolds and preserved most of their initial attributes, except for mechanical properties. However, although the scaffolds became weaker after sterilization, they were still robust enough to use as tissue engineering scaffolds and this treatment increased the proliferation of L929 fibroblasts while maintaining cell viability, suggesting that ozone gas treatment may be a suitable technique for the sterilization of polymer scaffolds which are significantly damaged by other methods.     

神经组织工程支架材料的研究进展

神经组织工程运用于中枢神经损伤与疾病治疗,用以恢复病变或损伤的中枢神经系统的解剖结构与功能,神经支架材料发挥支撑与营养作用。对神经组织工程中支架材料的研究现状进行综述,并提出面临的问题及今后的研究方向。     

静电纺纳米纤维基组织工程大孔支架的研究进展

静电纺丝作为一种纳米纤维支架的仿生构建方法,已在组织工程和再生医学领域中得到越来越多的应用和关注。但是,静电纺支架的主要问题是密集排列的纳米纤维之间的空隙很小,阻碍细胞的长入和三维(3 D)组织的形成。为了解决这一问题,近年来已发展了许多用于扩大静电纺纳米纤维支架孔尺寸的制备方法。首先概述组织工程支架中大孔对细胞行为的影响,然后对静电纺纳米纤维3 D大孔支架的制备方法和技术研究进展进行综述,讨论这些3 D大孔支架促进细胞长入的效果,最后对静电纺3 D大孔支架在组织工程中应用的主要挑战和前景,提出了看法。     

PCL and PCL-based materials in biomedical applications

Abstract

Biodegradable polymers have met with an increasing demand in medical usage over the last decades. One of such polymers is poly(ε-caprolactone) (PCL), which is a polyester that has been widely used in tissue engineering field for its availability, relatively inexpensive price and suitability for modification. Its chemical and biological properties, physicochemical state, degradability and mechanical strength can be adjusted, and therefore, it can be used under harsh mechanical, physical and chemical conditions without significant loss of its properties. Degradation time of PCL is quite long, thus it is used mainly in the replacement of hard tissues in the body where healing also takes an extended period of time. It is also used at load-bearing tissues of the body by enhancing its stiffness. However, due to its tailorability, use of PCL is not restricted to one type of tissue and it can be extended to engineering of soft tissues by decreasing its molecular weight and degradation time. This review outlines the basic properties of PCL, its composites, blends and copolymers. We report on various techniques for the production of different forms, and provide examples of medical applications such as tissue engineering and drug delivery systems covering the studies performed in the last decades.     

提高骨组织工程支架材料生物相容性的关键影响因素

骨组织工程领域除了对支架材料本身的构成和性能加以研究之外，其研究范围还包括：对支架材料的孔径、孔隙率及三维相通性的研究；种子细胞的筛选、生物活性因子的参与以及生物复合材料的构建等相关因素的研究，这些因素对支架材料的生物相容性以及体内的骨传导性和骨诱导性都至关重要。从这些方面人手，有可能使骨组织工程支架材料的发展取得长足的进步。     

光固化3D打印软组织材料的性能研究进展

光固化3D打印技术具有成型速度快、精度高的特点,可以精确控制需打印软组织的大小、形状和强度等,完成所需替代软组织支架的高匹配定制,有效解决软组织替代物的巨大缺口。目前该技术的应用范围取决于光敏材料的性能,首先,需具备适当的黏度、固化时间和固化收缩率等,以执行光固化打印并能控制打印组织的精度;其次,打印组织还需满足机体使用的机械性能(如强度、硬度、韧性)和良好的生物相容性(如促细胞黏附、增殖及分化),而降解性质、孔隙率、血管化等直接影响打印组织的机械性能或生物相容性。综述软组织支架打印所需光敏材料的基本性能和特殊性能要求及目前改良材料性能的方法,并展望光敏材料的发展趋势,对软组织工程光敏打印材料的开发具有指导意义。     

Design and fabrication of porous biodegradable scaffolds: a strategy for tissue engineering

Current strategies of tissue engineering are focused on the reconstruction and regeneration of damaged or deformed tissues by grafting of cells with scaffolds and biomolecules. Recently, much interest is given to scaffolds which are based on mimic the extracellular matrix that have induced the formation of new tissues. To return functionality of the organ, the presence of a scaffold is essential as a matrix for cell colonization, migration, growth, differentiation and extracellular matrix deposition, until the tissues are totally restored or regenerated. A wide variety of approaches has been developed either in scaffold materials and production procedures or cell sources and cultivation techniques to regenerate the tissues/organs in tissue engineering applications. This study has been conducted to present an overview of the different scaffold fabrication techniques such as solvent casting and particulate leaching, electrospinning, emulsion freeze-drying, thermally induced phase separation, melt molding and rapid prototyping with their properties, limitations, theoretical principles and their prospective in tailoring appropriate micro-nanostructures for tissue regeneration applications. This review also includes discussion on recent works done in the field of tissue engineering.     

泌尿外科组织工程的发展现状及展望

基于组织工程学的组织工程技术和干细胞研究在克服组织器官损伤、修复组织器官功能缺失及减少手术并发症等问题上现已取得很大进展。以往传统方法是利用生物替代材料修复组织,而组织工程技术注重将种子细胞与生物材料结合,形成与自身组织结构和功能相同的生物组织来修复组织缺损,优势在于通过组织工程技术可克服供体材料获取的局限性,并能有效减少并发症。组织工程技术的研究目的便是找到最终能很好替代原有组织生物学功能的合适的种子细胞、生物材料,构建适合的体内微环境。本文主要描述目前泌尿外科学中各领域组织工程的发展现状,探讨组织工程技术应用于治疗复杂泌尿系统疾病的未来趋势。本文研究结果显示,尽管目前临床试验还相对较少,但现有研究在动物模型上取得的良好结果揭示了组织工程技术今后用于治疗各种泌尿系统疾病的光明前景。     

Combining mechanical foaming and thermally induced phase separation to generate chitosan scaffolds for soft tissue engineering

In this paper, a novel foaming methodology consisting of turbulent mixing and thermally induced phase separation (TIPS) was used to generate scaffolds for tissue engineering. Air bubbles were mechanically introduced into a chitosan solution which forms the continuous polymer/liquid phase in the foam created. The air bubbles entrained in the foam act as a template for the macroporous architecture of the final scaffolds. Wet foams were crosslinked via glutaraldehyde and frozen at ?20 °C to induce TIPS in order to limit film drainage, bubble coalescence and Ostwald ripening. The effects of production parameters, including mixing speed, surfactant concentration and chitosan concentration, on foaming are explored. Using this method, hydrogel scaffolds were successfully produced with up to 80% porosity, average pore sizes of 120 μm and readily tuneable compressive modulus in the range of 2.6 to 25 kPa relevant to soft tissue engineering applications. These scaffolds supported 3T3 fibroblast cell proliferation and penetration and therefore show significant potential for application in soft tissue engineering.     

高分子纳米纤维在组织工程支架材料研究中的应用

介绍了高分子纳米纤维的特点、合成方法、生物相容性以及表明修饰,阐明其作为新型支架材料在骨组织工程中的应用价值。     

Factors Affecting the Longevity and Strength in an <Emphasis Type="Italic">In Vitro</Emphasis> Model of the Bone–Ligament Interface

The interfaces between musculoskeletal tissues with contrasting moduli are morphologically and biochemically adapted to allow the transmission of force with minimal injury. Current methods of tissue engineering ligaments and tendons do not include the interface and this may limit the future clinical success of engineered musculoskeletal tissues. This study aimed to use solid brushite cement anchors to engineer intact ligaments from bone-to-bone, creating a functional musculoskeletal interface in vitro. We show here that modifying anchor shape and cement composition can alter both the longevity and the strength of an in vitro model of the bone–ligament interface: with values reaching 23 days and 21.6 kPa, respectively. These results validate the use of brushite bone cement to engineer the bone–ligament interface in vitro and raise the potential for future use in ligament replacement surgery.     

组织工程人工肌腱的研究进展

本文对目前组织工程肌腱的研究成果作一综述,主要从细胞支架、种子细胞、生长因子、周期性张力等各方面进行了阐述。今后,对材料进行合理改进,使之能供给肌腱细胞最适合的生存环境,解决种子细胞的来源问题,加入适当的生长因子,并施以符合生理条件的周期性张力,组织工程化肌腱将成为修复肌腱缺损的一种理想而可靠的方法。     

超临界二氧化碳流体发泡技术制备组织工程支架及其泡孔形貌控制研究进展

组织工程支架作为细胞生长的载体,在组织工程再生组织的研究中具有非常重要的地位。传统方法在三维支架的理论研究与制备技术方面均已趋于成熟,但制备过程仍存在工艺复杂,有机溶剂难以去除,制备条件不利于保持生物分子活性等问题。近年来,超临界二氧化碳流体技术利用优越的传质性与环境友好性,已广泛用于制备各种三维结构的组织工程支架,其中以超临界发泡技术最为经典。三维多孔支架在超临界发泡技术制备过程中,泡孔形貌受材料性质、致孔剂种类及工艺参数等方面的影响。本文就采用该技术制备的多孔支架研究进展及存在的问题进行综述,同时对该技术控制泡孔形貌的发展方向提出展望。     

VEGF-mediated angiogenesis and vascularization of a fumarate-crosslinked polycaprolactone (PCLF) scaffold

Purpose: Revascularization of natural and synthetic scaffolds is a critical part of the scaffold’s incorporation and tissue ingrowth. Our goals were to create a biocompatible polymer scaffold with 3D-printing technology, capable of sustaining vascularization and tissue ingrowth. Methods: We synthesized biodegradable polycaprolactone fumarate (PCLF) scaffolds to allow tissue ingrowth via large interconnected pores. The scaffolds were prepared with Poly(lactic-co-glycolic acid)(PLGA) microspheres seeded with or without different growth factors including VEGF,FGF-2, and/or BMP-2. Scaffolds were implanted into the subcutaneous tissues of rats before undergoing histologic and microCT angiographic analysis.

Results: At harvest after 12 weeks, scaffolds had tissue infiltrating into their pores without signs of scar tissue formation, fibrous capsule formation, or immune responses against PCLF. Histology for M1/M2 macrophage phenotypes confirmed that there were no overt signs of immune responses. Both microCT angiography and histologic analysis demonstrated marked tissue and vessel ingrowth throughout the pores traversing the body of the scaffolds. Scaffolds seeded with microspheres containing VEGF or VEGF with either BMP-2 or FGF-2 had significantly higher vascular ingrowth and vessel penetration than controls. All VEGF-augmented scaffolds were positive for Factor-VIII and exhibited collagen tissue infiltration throughout the pores. Furthermore, scaffolds with VEGF and BMP-2 had high levels of mineral deposition throughout the scaffold that are attributable to BMP-2.

Conclusions: PCLF polymer scaffold can be utilized as a framework for vascular ingrowth and regeneration of multiple types of tissues. This novel scaffold material has promise in tissue regeneration across all types of tissues from soft tissue to bone.     

Tissue Engineering Strategies for the Regeneration of Orthopedic Interfaces

A major focus in the field of orthopedic tissue engineering is the development of tissue engineered bone and soft tissue grafts with biomimetic functionality to allow for their translation to the clinical setting. One of the most significant challenges of this endeavor is promoting the biological fixation of these grafts with each other as well as the implant site. Such fixation requires strategic biomimicry to be incorporated into the scaffold design in order to re-establish the critical structure–function relationship of the native soft tissue-to-bone interface. The integration of distinct tissue types (e.g. bone and soft tissues such as cartilage, ligaments, or tendons), necessitates a multi-phased or stratified scaffold with distinct yet continuous tissue regions accompanied by a gradient of mechanical properties. This review discusses tissue engineering strategies for regenerating common tissue-to-tissue interfaces (ligament-to-bone, tendon-to-bone, or cartilage-to-bone), and the strategic biomimicry implemented in stratified scaffold design for multi-tissue regeneration. Potential challenges and future directions in this emerging field will also be presented. It is anticipated that interface tissue engineering will enable integrative soft tissue repair, and will be instrumental for the development of complex musculoskeletal tissue systems with biomimetic complexity and functionality.     

水凝胶材料和间充质干细胞在组织工程中的应用进展

随着组织工程学的发展, 人们越来越关注将水凝胶作为支架材料并与细胞3D培养相结合用于组织器官再生与修复。水凝胶由亲水性聚合物、共聚物或可以形成大分子链的单体大分子交联而成, 可吸收大量水分并保持3D结构, 具有良好的生物相容性、可包埋细胞和有效的递送生物活性分子等特点, 因而被广泛用于生物医药领域的药物输送和组织工程等领域。间充质干细胞可以从骨髓、脂肪、脐带等多种组织中获取, 具有低免疫原性及多向分化潜能, 是细胞3D培养以及细胞治疗的首选。目前间充质干细胞主要是2D培养模式, 该培养模式下的间充质干细胞繁殖率低, 且无法模拟体内的生长环境。水凝胶材料作为3D细胞培养支架具有良好的相容性, 可以模拟体内的生长环境, 在修复受损软骨、骨、皮肤和心脏等组织中有巨大潜力。概述水凝胶、间充质干细胞以及间充质干细胞和水凝胶材料在组织工程中的应用, 展示水凝胶材料与间充质干细胞的3D培养在不同组织再生和修复中的发展趋势和可能性, 以期为后续水凝胶和干细胞的深入应用研究提供参考。     

骨组织工程种子细胞的研究进展

随着骨组织工程研究的进展 ,选择什么细胞作为其种子细胞成为近年来研究的热点。目前 ,骨组织工程应用中种子细胞有五种来源 :骨、骨膜、骨髓、骨外组织和早期胚胎。本文介绍了五种来源种子细胞的研究状况 ,并对种子细胞各自存在的问题及应用前景进行了分析。