Human microvasculature fabrication using thermal inkjet printing technology

The current tissue engineering paradigm is that successfully engineered thick tissues must include vasculature. As biological approaches alone, such as VEGF, have fallen short of their promises, one may look for an engineering approach to build microvasculature. Layer-by-layer approaches for customized fabrication of cell/scaffold constructs have shown some potential in building complex 3D structures. With the advent of cell printing, one may be able to build precise human microvasculature with suitable bio-ink. Human microvascular endothelial cells (HMVEC) and fibrin were studied as bio-ink for microvasculature construction. Endothelial cells are the only cells to compose the human capillaries and also form the entire inner lining of cardiovascular system. Fibrin has been already widely recognized as tissue engineering scaffold for vasculature and other cells, including skeleton/smooth muscle cells and chondrocytes. In our study, we precisely fabricated micron-sized fibrin channels using a drop-on-demand polymerization. This printing technique uses aqueous processes that have been shown to induce little, if any, damage to cells. When printing HMVEC cells in conjunction with the fibrin, we found the cells aligned themselves inside the channels and proliferated to form confluent linings. The 3D tubular structure was also found in the printed patterns. We conclude that a combined simultaneous cell and scaffold printing can promote HMVEC proliferation and microvasculature formation.     

3D打印技术在神经外科的应用优势

文题释义：3D打印：是在一种在计算机控制下将材料连接或凝固以创建三维物体的快速成型技术,目前在生物医学领域应用广泛。神经外科：是研究人体神经系统,如脑、脊髓及周围神经系统疾病的病因、发病机制,并探索新的诊断、治疗、预防技术的一门高精尖学科。背景：神经系统解剖结构复杂,相关疾病种类繁多,手术难度大,风险高。它不仅要求医生将病变组织完整切除,还有避免术中对重要神经、血管及功能区造成损伤,因而临床上一直在探索定位准确、手术精度高的治疗方式及相关辅助手段。3D打印是一种快速成型的技术,近年来发展迅猛,目前已经广泛应用于生物医学行业。目的：综述3D打印技术在神经外科常见疾病中的应用现状,并对应用前景进行展望。方法：第一作者以关键词通过计算机检索中国知网(CNKI)、万方数据库、PubMed和Web of Science数据库,检索截止日期为2020年2月的人类研究。检索出相关文献385篇,根据纳入与排除标准,并进行文献增补,最终纳入49篇文献进行综述。结果与结论：①在神经外科领域,3D打印定制个体化植入物可用于修补颅骨缺损,所打印出的病变模型可用于畸形修复、脑血管病、颅底疾病及脊柱脊髓疾病手术的术前模拟,为个体化精准治疗提供依据;②同时模型可用于神经外科教育及术前宣教;③因此3D打印技术在神经外科领域具有广阔的发展前景。ORCID: 0000-0001-8453-906X(温稀超)中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Novel 3D collagen scaffolds fabricated by indirect printing technique for tissue engineering

This article reports the mechanical properties and in vitro evaluation of a collagen scaffold fabricated using an indirect 3D printing technique. Collagen scaffolds, featuring predefined internal channels and capillary networks, were manufactured using phase change printing. It was observed that the collagen scaffolds featured internal channels and a hierarchical structure that varied over length scales of 10-400 microm. In vitro evaluation using hMSCs demonstrated that the resultant collagen based scaffolds have the ability to support hMSC cell attachment and proliferation; cells can migrate and survive deep within the structure of the scaffold. The cell numbers increased 2.4 times over 28 days in culture for the lysine treated scaffolds. The cells were spread along the collagen fibers to form a 3D structure and extracellular matrix was detected on the surface of the scaffolds after 4 weeks in culture. The crosslinking treatment enhanced the biostability and dynamic properties of the collagen scaffolds significantly.     

3D打印技术在创伤骨科中的应用进展

随着3D打印技术的不断发展,其在创伤骨科领域中的应用越来越广泛,几乎涵盖了人体所有的解剖区域。3D打印技术也被称为"增材制造技术"和"快速成形技术",被认为是"第二次工业革命"。3D打印技术不仅可以打印出患者特异性的解剖实体模型,便于医师对患者复杂的解剖结构及疾病有更好的理解,同时有助于医学教育和手术培训,而且对于一些特殊患者可以制造定制的植入导板及假体,匹配患者的解剖结构,有效解决临床治疗难题。本文就3D打印技术在创伤骨科中的应用进展进行综述。     

3D打印技术在脊柱外科的应用

BACKGROUND: Three-dimensional printing technology is a new technology which can quickly and accurately transform the virtual computer-aided design into the three-dimensional physical prototypes. Three-dimensional printing physical model method can replace the method of traditional preoperative planning and repair surgical simulation, with the characteristic of repeatable, which has been deepened day after day in clinical application of spine surgery. OBJECTIVE: To summarize the application status of three-dimensional printing technology in spine surgery and look forward to its future development directions. METHODS: The articles regarding the application of three-dimensional printing technology on clinical applications in spine surgery were retrieved from PubMed databases, Google Scholar, China National Knowledge Infrastructure and Wanfang Database from January 2000 to July 2015. The key words were 3D printing technology, rapid prototyping technology, spine, vertebra, department of orthopedics, fracture, joint, hand and foot, bone tumor, trauma, cervical vertebrae, thoracic vertebrae, lumbar vertebrae, sacral vertebrae, pedicle of vertebral arch, vertebral body, intervertebral disc, and clinical application. A total of 50 articles with a good representation were selected and discussed after repetitive studies and reviews were excluded. RESULTS AND CONCLUSION: The three-dimensional printing technique has been applied in preoperative diagnosis, individualized orthosis customerization, the communication between doctors and patients, teaching, the formulation of individualized and high-accurate repairing plan, intraoperative navigation and individualized implant customization. These results suggest that with the rapid development of medical imaging, digital medicine and technologies of the cell and tissue culture and new materials, three-dimensional printing technology will have a wide range of applications in spine surgery.       

体外构建3D人工皮肤

BACKGROUND: Epidermis is unable to differentiate into stratum corneum and other parts in the previous artificial skin constructed using three-dimensional printing. OBJECTIVE: To optimize the method of artificial skin construction to obtain more feasible artificial skin. METHODS: Type I collagen extracted from rat-tail and bovine tail was purified. Primary dermal fibroblasts and keratinocytes were isolated from children’s foreskin, and then embedded in bovine or rat tail collage to construct the dermis; keratinocytes were seeded on the dermis for 7 days, followed by 7-day air liquid interface, and the artificial skin was finally achieved. The contraction and hydrophobicity by water contact angle were detected, as well as the morphology was observed by hematoxylin-eosin staining, sirius red staining and immunofluorescence analysis. RESULTS AND CONCLUSION: Seven days after fibroblasts embedded in collagen, the area of bovine collagen was reduced by 21%, while that of rat tail collagen decreased about a half. The water contact angle of the skin constructed by bovine tail collagen was similar to that of human skin, which was much higher than that of the skin constructed by rat tail collagen. Sirius red staining found that the skin constructed by bovine tail collagen had stronger refractivity, more intact structure and thicker fibers than those of the skin constructed by rat tail collagen. Moreover, more multilayer keratinocytes appeared in the skin constructed by bovine tail collagen through hematoxylin-eosin staining. In conclusion, bovine tail collagen is more available for the artificial skin construction. 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

Cytocompatibility of brushite and monetite cell culture scaffolds made by three-dimensional powder printing

This study investigated the cytocompatibility of low-temperature direct 3-D printed calcium phosphate scaffolds in vitro. The fabrication of the scaffolds was performed with a commercial 3-D powder printing system. Diluted phosphoric acid was printed into tricalcium phosphate powder, leading to the formation of dicalcium phosphate dihydrate (brushite). Hydrothermal conversion of the brushite matrices led to the formation of dicalcium phosphate anhydrous (monetite). The biocompatibility was investigated using the osteoblastic cell line MC3T3-E1. Cell viability and the expression of alkaline phosphatase served as parameters. The culture medium was analyzed for pH value, concentration of free calcium and phosphate ions and osteocalcin. Both types of scaffolds showed a considerable increase of cell proliferation and viability; the monetite matrices were a little inferior compared with the brushite ones. The activity of alkaline phosphatase showed a similar pattern. Optical and electron microscopy revealed an obvious cell growth on the surface of both materials. Analysis of the culture medium showed minor alterations of pH value within the physiological range. The concentrations of free calcium and phosphate ions were obviously different among brushite and monetite cultures, due to their different solubility. The content of osteocalcin of the culture medium was reduced by the printed scaffolds due to adsorption. We conclude that the powder printed brushite and monetite matrices have a suitable biocompatibility for their use as cell culture scaffolds. Both materials enable osteoblastic cells in vitro to proliferate and differentiate due to the expression of typical osteoblastic markers.     

不同烧结温度下三维打印成型多孔钛植入体的实验研究

目的 评价三维打印成型技术(3DP)用于多孔钛植入体制备的可行性,研究不同烧结温度对其组织结构和力学性能的影响.方法 设计试件大小为25×20 mm圆柱体,设定每层的黏结面积为80％.选择纯度98.5％、颗粒直径约75 μm的钛粉为原料,聚乙烯醇粉作为黏结剂,聚乙烯吡咯烷酮粉作为辅助黏结剂.通过三维打印获得多孔钛植入体试件初胚,在氩气保护下,将试件分别烧结至1 200、1 300、1 400℃;对烧结完成的试件进行性能检测,包括孔隙率、显微硬度、扫描电镜观察试件的显微结构、抗压强度及弹性模量.结果 最终获得的多孔钛植入体试件,其收缩均匀、无明显变形、细节清晰、肉眼可见排列整齐的微孔结构、表面无裂纹,呈现金属光泽.在1 200、1 300、1 400℃的烧结温度下,孔隙率分别为(65.01±1.03)％、(46.73±0.73)％、(41.06±0.31)％,显微硬度为115.2±0.6、148.6±1.1、182.8±2.1,弹性模量为(5.9±0.5)、(16.2±0.9)、(34.8±1.5) GPa,抗压强度为(81.3±4.3)、(135.4±8.5)、(218.6±7.1)MPa.扫描电镜观察其孔隙相互连通成三维网状结构.结论 证实了应用三维打印成型技术制备多孔钛植入体的可行性,得到的多孔钛植入体具有与骨组织相匹配的良好的生物力学相容性.     

MEMS-based fabrication and microfluidic analysis of three-dimensional perfusion systems

This paper describes fabrication and fluidic characterization of 3D microperfusion systems that could extend the viability of high-density 3D cultures in vitro. High-aspect ratio towers serve as 3D scaffolds to support the cultures and contain injection sites for interstitial delivery of nutrients, drugs, and other reagents. Hollow and solid-top tower arrays with laser ablated side-ports were fabricated using SU-8. Appropriate sizing of fluidic ports improves the control of agent delivery. Microfluidic perfusion can be used to continuously deliver equal amount of nutrients through all ports, or more media can be delivered at some ports than the others, thus allowing spatial control of steady concentration gradients throughout the culture thickness. The induced 3D flow around towers was validated using micro particle image velocimetry. Based on experimental data, the flow rates from the characteristic ports were found to follow the analytical predictions.     

3D打印技术在髋关节置换中的应用及价值

BACKGROUND: Three-dimensional (3D) printing technology is a new rapid prototyping technology, which has been initially applied in orthopedics, especially in the clinical application of hip replacement surgery.     

三维打印技术在骨组织工程领域的应用研究进展

综述了三维(3D)打印技术的出现、分类与优势等.介绍了该技术在骨组织工程领域的应用,包括光固化立体印刷、熔融沉积成型、选择性激光烧结和3D喷印的工作原理、存在的优缺点以及国内外学者在该领域的研究进展.目前骨组织工程支架的制备大多应用了3D打印技术,以生物可降解的活性材料为原料制备而成.在我国该领域虽然发展迅速,利用3D打印技术进行人工骨合成、骨科术前模拟等已经越来越普遍,亦取得了令人满意的效果,但要研发出合适的生物材料以及设备精度的改进仍是亟待解决的问题.目前,仿生器官的功能化已成为3D打印技术领域的一大困难,其中多细胞共培养、血管化及支架的制备是实现功能化必须克服的问题,相信通过努力,该项技术将会为器官的再生与修复带来更多令人瞩目的成果.     

三维打印组织工程牙计算机辅助设计建模技术的应用

背景：国内外关于如何成功构建组织工程牙支架材料内部空间构型的文献报道较少。 目的：建立适用于组织工程牙需求的支架材料CAD空间构型及支架结构实体微观模型STL格式文件。 方法：采用MICRO CT对离体大鼠第二磨牙进行连续扫描,将MICRO CT获得的DICOM格式文件导入MIMICS软件,将生成的三维模型导入GEOMAGIC12软件,提取外层轮廓,利用偏移功能模拟得到大鼠磨牙外层轮廓数据。利用CATIA V5R17软件构建支架材料空间内部多孔微观模型单体,在空间合适坐标上阵列得到组织工程牙内部支架整体模型,通过变更单体构型还可快速建立多种整体支架构型。装配大鼠磨牙外层轮廓数据与内部空间支架得到三维打印组织工程牙CAD 模型STL文件。 结果与结论：成功建立了牙体组织支架微观结构CAD模型,该CAD STL模型可直接用于三维打印系统快速成型组织工程牙支架。说明基于结合计算机逆向与正向工程建模技术,可快速建立多种符合组织工程牙要求的支架材料空间构型。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      

3D打印技术在骨科关节中的应用进展

【摘要】随着新材料技术的不断发展,3D打印技术在骨科关节领域中的应用越来越广泛。本文综述了3D打印技术在骨科关节中的研究进展,分别介绍了3D打印在解剖学教育、医生和患者及其家属的术前沟通、临床治疗方案设计的应用,并对关节置换和骨关节软骨修复在组织工程领域的进展进行了阐述。最后,对3D打印技术在该领域未来的机遇和挑战进行了预测。     

Mechanical properties and degradation of drug eluted bioresorbable vascular scaffolds prepared by three-dimensional printing technology

Bioresorbable vascular scaffolds are expected to replace the traditional metal stent, avoiding the long-term complications of metal stents. However, it is hard for the traditional scaffold manufacturing process to meet the requirements of individualized treatment for vascular lesions, which requires different morphologies. Here, we used a new method of scaffold manufacturing, three-dimensional printing technology, to prepare bioresorbable vascular scaffolds. The fabricated scaffold was loaded with sirolimus mixed with scaffold preparation material for slow drug release. The engineered, drug- loaded, bioresorbable vascular scaffold (BVS) was analyzed and tested in vivo. The scaffolds produced by three-dimensional printing technology exhibited good mechanical properties and in vitro degradation performance. The results also suggested that these scaffolds could maintain effective radial strength after long-term degradation and sustained release of the drug. As a new scaffold preparation method, it may provide a promising idea for developing bioresorbable vascular scaffold technology.     

Scaffold design and fabrication technologies for engineering tissues--state of the art and future perspectives

Today, tissue engineers are attempting to engineer virtually every human tissue. Potential tissue-engineered products include cartilage, bone, heart valves, nerves, muscle, bladder, liver, etc. Tissue engineering techniques generally require the use of a porous scaffold, which serves as a three-dimensional template for initial cell attachment and subsequent tissue formation both in vitro and in vivo. The scaffold provides the necessary support for cells to attach, proliferate, and maintain their differentiated function. Its architecture defines the ultimate shape of the new grown soft or hard tissue. In the early days of tissue engineering, clinically established materials such as collagen and polyglycolide were primarily considered as the material of choice for scaffolds. The challenge for more advanced scaffold systems is to arrange cells/tissue in an appropriate 3D configuration and present molecular signals in an appropriate spatial and temporal fashion so that the individual cells will grow and form the desired tissue structures--and do so in a way that can be carried out reproducibly, economically, and on a large scale. This paper is not intended to provide a general review of tissue engineering, but specifically concentrate on the design and processing of synthetic polymeric scaffolds. The material properties and design requirements are discussed. An overview of the various fabrication techniques of scaffolds is presented, beginning with the basic and conventional techniques to the more recent, novel methods that combine both scaffold design and fabrication capabilities.     

鞍区病变3D打印模型的临床应用观察

目的 探讨根据薄层增强扫描数据制作的鞍区占位性病变3D打印模型在术前制订手术计划和术中指导手术操作中的应用价值。方法 采用前瞻性研究方法,纳入2015年3月—2017年6月解放军福州总医院神经外科15例鞍区病变患者,其中男6例、女9例,年龄40~75岁;垂体腺瘤13例,鞍结节脑膜瘤和颈内动脉床突上段动脉瘤各1例。将CTA、MRI薄层扫描数据输入Mimic软件,建立数字模型,通过3D打印机制作模型。在3D打印模型上分析病变与周围结构的解剖关系、模拟建立手术入路并进行模拟手术操作,确定手术方案。临床采用经单侧鼻孔-蝶窦入路显微手术切除垂体腺瘤13例、开颅手术切除鞍结节脑膜瘤1例、开颅手术夹闭左侧颈内动脉床突上段大型动脉瘤1例,并在手术中进一步参考和验证模型的模拟结果。结果 3D打印模型上,13例垂体腺瘤在经鼻蝶入路视角下,可清晰显示鞍底隆突的形态、蝶窦的大小、气化分型、蝶窦分隔情况和蝶窦后壁形态,还可观察侧壁的骨性隆突;根据影像和3D模型观察结果进行适当地鞍底开窗,外侧缘不累及颈内动脉,上缘达到前海绵间窦,下方显露充分。1例鞍结节脑膜瘤及1例动脉瘤患者病变均与前床突关系密切,术中所见与3D打印模型所见一致。15例患者临床手术均顺利完成,术中、术后无血管及重要脑组织结构损伤、脑脊液漏、感染等并发症发生。结论 3D打印模型可清晰显示鞍区病变与周围骨质、血管的关系,为术前手术方案设计提供了良好、直观的立体解剖结构观察,并可用于模拟手术操作,进而提高手术安全性和成功率。     

数字化结合3D打印技术辅助复杂骨盆骨折的手术设计

目的　探讨Mimics14. 11软件数字化结合3D打印模型模拟手术辅助复杂骨盆骨折内固定的手术设计。 方法　筛选1例复杂骨盆骨折患者,将患者的骨盆及全套内固定物的薄层CT数据导入Mimics 14.11软件,进行骨折三维建模、骨折块虚拟复位、建立骨盆内固定物标准件库、选取最佳匹配的钢板及螺钉。3D打印出患者1:1的骨盆实体模型, 在模型上按照数字化设计进行模拟手术,将骨盆重建板的位置、钉道长度和方向同数字化设计比较,确定术中使用的钢板及螺钉。最后,按照术前演练进行实际手术骨折复位、钢板内固定。 结果　模拟手术共植入2块重建钢板和15枚螺钉,钢板植入的位置、螺钉植入的方向均与数字化术前设计高度一致,钉道长度与数字化术前设计比较无显著性差异(P>0.05)。实际手术与模拟手术的手术效果一致。 结论　数字化设计结合3D打印技术实现了复杂型骨盆骨折的个体化、精准化治疗,明显减少了患者的出血量,缩短了患者的康复周期。     

三维打印双相磁性纳米复合支架材料的性能测定

目的研究制备出一种新型双相磁性纳米复合支架材料(PLGA/Col-I-PLGA/n-HA/Fe_2O_3),通过各项生物学性能检测,评价并探讨其作为骨组织工程支架的可行性。方法通过低温快速成型方法制备双相磁性纳米复合支架材料(PLGA/Col-I-PLGA/n-HA/Fe_2O_3),采用电子试验机检测支架材料的抗弯,抗压,弹性模量评价其力学性能,通过电镜观察支架材料超微结构;以介质(乙醇)浸泡法测定支架材料的孔隙率,将支架材料与骨髓间充质干细胞复合共培养,检测其生物相容性。结果双相磁性纳米复合支架材料力学检测结果显示其具有良好的力学性能,电镜观察结果显示上下两层孔径均匀分布,上层软骨相孔径较小,中间连续相良好融合,孔径及孔隙率检测结果显示软骨层支架的孔径为189um,孔隙率86.5%。骨层支架的孔径为364um,孔隙率77.1%,符合双层支架材料的设计要求。双相磁性纳米复合支架材料与骨髓间充质干细胞共培养,结果显示骨髓间充质干细胞的增殖效果很好,能更好的促进分化为目的细胞,说明双相磁性纳米复合支架材料具有良好的生物相容性。结论双相磁性纳米复合支架材料(PLGA/Col-I-PLGA/n-HA/Fe_2O_3)有很好的力学性能和生物相容性,孔径及孔隙率达到细胞粘附生长的要求,与正常的关节软骨及软骨下骨生理结构更加接近,有望可以更好的修复骨关节炎或者外伤等疾病带来的软骨和软骨下骨损伤。     

New depowdering-friendly designs for three-dimensional printing of calcium phosphate bone substitutes

Powder-based three-dimensional printing (3DP) is a versatile method that allows creating synthetic calcium phosphate (CaP) scaffolds of complex shapes and structures. However, one major drawback is the difficulty of removing all remnants of loose powder from the printed scaffolds, the so-called depowdering step. In this study, a new design approach was proposed to solve this problem. Specifically, the design of the printed scaffolds consisted of a cage with windows large enough to enable depowdering while still trapping loose fillers placed inside the cage. To demonstrate the potential of this new approach, two filler geometries were used: sandglass and cheese segment. The distance between the fillers was varied and they were either glued to the cage or free to move after successful depowdering. Depowdering efficiency was quantified by microstructural morphometry. The results showed that the use of mobile fillers significantly improved depowdering. Based on this study, large 3DP scaffolds can be realized, which might be a step towards a broader clinical use of 3D printed CaP scaffolds.