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Original Articles

by Rui Yao, Ahmed Yousef F Alkhawtani, Ruoyu Chen, Jie Luan, Mingen Xu
53 Views, 29 PDF Downloads

Rapid reconstruction of functional microvasculature is the urgent challenge of regenerative medicine and ischemia therapy development. The purpose of this study was to assess whether hydrogel based microspheres coated by human umbilical vein endothelial cells (HUVECs) can direct rapid and efficient in vivo angiogenesis without the addition of exogenous growth factors or other supporting cells. Uniform alginate microspheres with adjustable diameter were biofabricated by electro-assisted bioprinting technology. Collagen fibrils were evenly coated on the surface of alginate microspheres via simple self-assembly procedure, and collagen concentration is optimized to achieve highest HUVECs adhesion and proliferation. Immunofluorescence staining and gene analysis confirmed the formation of prevascularized tubular structure and significantly enhanced endothelial gene expression. HUVECs-coated hydrogel microspheres with different diameters were subcutaneously injected in immune-deficient mice, which demonstrated rapid blood vessel regeneration and functional anastomosis with host blood vessels within one week. Besides, microsphere diameter demonstrated influence on blood vessel density with statistical differences, but showed no obvious influence on the area occupied by blood vessels. This study provided a powerful tool for rapid and minimal-invasion angiogenesis of bioprinting constructs and a potential method for vascularized tissue regeneration and ischemia treatment with clinically relevant dimensions. 

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Original Articles

by Yi-Hsuan Ou, Yi-Hui Ou, Jing Gu, Lifeng Kang
59 Views, 45 PDF Downloads

Topical anesthetics are widely used in dental procedures. However, most commercially available medications are in the form of liquid or semisolid, which cannot provide prolonged effect intraorally. To address this issue, we proposed the use of three-dimensional printing (3DP) to fabricate a customizable dental anesthetic patch loaded with lidocaine that can be fitted perfectly onto the affected tooth. It has been shown that that patch can adhere on the tooth for more than 1 h, while releasing lidocaine from the patch made of hydrogels. In addition, the results illustrated the possibility of controlling the drug release profile by altering the shape of the patch, as well the use of a 3DP tooth model as the drug testing platform. Taken together, these data further reinforce the vast potential of the application of 3DP technology in personalized medicine.

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Original Articles

by Ming-You Shie, Hsin-Yuan Fang, Yen-Hong Lin, Alvin Kai-Xing Lee, Joyce Yu, Yi-Wen Chen
54 Views, 26 PDF Downloads

In recent years, the additive manufacture was popularly used in tissue engineering, as the various technologies for this field of research can be used. The most common method is extrusion, which is commonly used in many bioprinting applications, such as skin. In this study, we combined the two printing techniques; first, we use the extrusion technology to form the ceramic scaffold. Then, the stem cells were printed directly on the surface of the ceramic scaffold through a piezoelectric nozzle. We also evaluated the effects of polydopamine (PDA)-coated ceramic scaffolds for cell attachment after printing on the surface of the scaffold. In addition, we used fluorescein isothiocyanate to simulate the cell adhered on the scaffold surface after ejected by a piezoelectric nozzle. Finally, the attachment, growth, and differentiation behaviors of stem cell after printing on calcium silicate/polycaprolactone (CS/PCL) and PDACS/PCL surfaces were also evaluated. The PDACS/PCL scaffold is more hydrophilic than the original CS/PCL scaffold that provided for better cellular adhesion and proliferation. Moreover, the cell printing technology using the piezoelectric nozzle, the different cells can be accurately printed on the surface of the scaffold that provided and analyzed more information of the interaction between different cells on the material. We believe that this method may serve as a useful and effective approach for the regeneration of defective complex hard tissues in deep bone structures.

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Original Articles

by Sanjairaj Vijayavenkataraman, Novelia Vialli, Jerry Y.H. Fuh, Wen Feng Lu
46 Views, 23 PDF Downloads

Bioprinting is increasingly being used for fabrication of engineered tissues for regenerative medicine, drug testing and other biomedical applications. The success of this technology lies with development of suitable bioinks and hydrogels that are specific to the intended tissue application. For applications such as neural tissue engineering, conductivity plays an important role in determining the neural differentiation and neural tissue regeneration. Although several conductive hydrogels based on metal nanoparticles such as gold and silver, carbon-based materials such as graphene and carbon nanotubes (CNTs) and conducting polymers such as polypyrrole (PPy), and polyaniline (PANi) were used, they possess several disadvantages. The long-term cytotoxicity of metal nanoparticles and carbon-based materials restricts their use in regenerative medicine. The conductive polymers on the other hand are non-biodegradable and possess weak mechanical properties limiting their printability into 3D constructs. The aim of this study is to develop a biodegradable, conductive and printable hydrogel based on collagen and a block copolymer of PPy and Polycaprolactone (PCL) (PPy-b-PCL) for bioprinting of neural tissue constructs. The printability including the influence of the printing speed and material flowrate on the printed fiber width, rheological properties and cytotoxicity of these hydrogels were studied. The results prove that the collagen/PPy-b-PCL hydrogels possessed better printability and biocompatibility. Thus, the collagen/PPy-b-PCL hydrogels reported in this study has the potential to be used in the bioprinting of neural tissue constructs for repair of damaged neural tissues and for drug testing or precision medicine applications.

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