Vol 4, No 2 (2018)

ONLINE FIRST

Table of Contents

Review Articles

by Cijun Shuai, Wenjing Yang, Shuping Peng, Chengde Gao, Wang Guo, Yuxiao Lai, Pei Feng
226 Views, 21 PDF Downloads
Physical stimulations such as magnetic, electric and mechanical stimulation could enhance cell activity and promote bone formation in bone repair process via activating signal pathways, modulating ion channels, regulating bone-related gene expressions, etc. In this paper, bioeffects of physical stimulations on cell activity, tissue growth and bone healing were systematically summarized, which especially focused on their osteogenesis-inducing mechanisms. Detailedly, magnetic stimulation could produce Hall effect which improved the permeability of cell membrane and promoted the migration of ions, especially accelerating the extracellular calcium ions to pass through cell membrane. Electric stimulation could induce inverse piezoelectric effect which generated electric signals, accordingly up-regulating intracellular calcium levels and growth factor synthesis. And mechanical stimulation could produce mechanical signals which were converted into corresponding biochemical signals, thus activating various signaling pathways on cell membrane and inducing a series of gene expressions. Besides, the equipments of physical stimulation system were discussed. The opportunities and challenges of physical stimulations were also presented from the perspective of bone repair.
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Review Articles

by Deepak Choudhury, Shivesh Anand, May Win Naing
65 Views, 48 PDF Downloads

The dawn of commercial bioprinting is rapidly advancing the tissue engineering field. In the past few years, new bioprinting approaches as well as novel bioinks formulations have emerged, enabling biological research groups to demonstrate the use of such technology to fabricate functional and relevant tissue models. In recent years, several companies have launched bioprinters pushing for early adoption and democratisation of bioprinting. This article reviews the progress in commercial bioprinting since the inception, with a particular focus on the comparison of different available printing technologies and important features of the individual technologies as well as various existing applications. Various challenges and potential design considerations for next generations of bioprinters are also discussed.

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Review Articles

by Hooi Yee Ng, Kai-Xing Alvin Lee, Che-Nan Kuo, Yu-Fang Shen
28 Views, 30 PDF Downloads
Vascular networks have an important role to play in transporting nutrients, oxygen, metabolic wastes and maintenance of homeostasis. Bioprinting is a promising technology as it is able to fabricate complex, specific multi-cellular constructs with precision. In addition, current technology allows precise depositions of individual cells, growth factors and biochemical signals to enhance vascular growth. Fabrication of vascularized constructs has remained as a main challenge till date but it is deemed as an important stepping stone to bring organ engineering to a higher level. However, with the ever advancing bioprinting technology and knowledge of biomaterials, it is expected that bioprinting can be a viable solution for this problem. This article presents an overview of the biofabrication of vascular and vascularized constructs, the different techniques used in vascular engineering such as extrusion-based, droplet-based and laser-based bioprinting techniques, and the future prospects of bioprinting of artificial blood vessels.
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Review Articles

by Cavin Tan, Wei Yan Toh, Gladys Wong, Li Lin
6 Views, 6 PDF Downloads

To help people with dysphagia increase their food intake, 3D printing can be used to improve the visual appeal of pureed diets. In this review, we have looked at the works done to date on extrusion-based 3D food printing with an emphasis on the edible materials (food inks) and machinery (printers) used. We discuss several methods that researchers have employed to modify conventional food materials into printable formulations. In general, additives such as hydrocolloids may modify the rheological properties and texture of a pureed food to confer printability. Some examples of such additives include starch, pectin, gelatin, nanocellulose, alginate, carrageenan etc. In the second part, we have looked at various food printers that have been developed for both academic and commercial purposes. We identified several common advantages and limitations that these printers shared. Moving forward, future research into food printer development should aim to improve on these strengths, eliminate these limitations and incorporate new capabilities.

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Original Articles

by Cijun Shuai, Youwen Yang, Pei Feng, Shuping Peng, Wang Guo, Anjie Min, Chengde Gao
511 Views, 185 PDF Downloads

It is critical to develop a fabrication technology for precisely controlling an interconnected porous structure of scaffolds to mimic the native bone microenvironment. In this work, a novel combined process of additive manufacturing (AM) and chemical etching was developed to fabricate graphene oxide/poly(L-lactic acid) (GO/PLLA) scaffolds with multi-scale porous structure. Specially, AM was used to fabricate an interconnected porous network with pore sizes of hundreds of microns. And the chemical etching in sodium hydroxide solution constructed pores with several microns or even smaller on scaffolds surface. The degradation period of the scaffolds was adjustable via controlling the size and quantity of pores. Moreover, the scaffolds exhibited surprising bioactivity after chemical etching, which was ascribed to the formed polar groups on scaffolds surfaces. Furthermore, GO improved the mechanical strength of the scaffolds.

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Original Articles

by Xiaoxiao Han, Julien Courseaus, Jamel Khamassi, Nadine Nottrodt, Sascha Engelhardt, Frank Jacobsen, Claas Bierwisch, Wolfdietrich Meyer, Torsten Walter, Jürgen Weisser, Raimund Jaeger, Richard Bibb, Russell Harris
531 Views, 86 PDF Downloads

This paper demonstrates the essential and efficient methods to design, and fabricate optimal vascular network for tissue engineering structures based on their physiological conditions. Comprehensive physiological requirements in both micro and macro scales were considered in developing the optimisation design for complex vascular vessels. The optimised design was then manufactured by stereolithography process using materials that are biocompatible, elastic and surface bio-coatable. The materials are self-developed photocurable resin consist of BPA-ethoxylated-diacrylate, lauryl acrylate and isobornylacrylate with Irgacure® 184, the photoinitiator. The optimised vascular vessel offers many advantages: 1) it provides the maximum nutrient supply; 2) it minimises the recirculation areas and 3) it allows the wall shear stress on the vessel in a healthy range. The stereolithography manufactured vascular vessels were then embedded in the hydrogel seeded with cells. The results of in vitro studies show that the optimised vascular network has the lowest cell death rate compared with a pure hydrogel scaffold and a hydrogel scaffold embedded within a single tube in day seven. Consequently, these design and manufacture routes were shown to be viable for exploring and developing a high range complex and specialised artificial vascular networks. 

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Original Articles

by Wafaa Arab, Sakandar Rauf, Ohoud Al-Harbi, Charlotte Hauser
9 Views, 3 PDF Downloads
The ability of skeletal muscle to self-repair after a traumatic injury, tumor ablation, or muscular disease is slow and limited, and the capacity of skeletal muscle to self-regenerate declines steeply with age. Tissue engineering of functional skeletal muscle using 3D bioprinting technology is promising for creating tissue constructs that repair and promote regeneration of damaged tissue. Hydrogel scaffolds used as biomaterials for skeletal muscle tissue engineering can provide chemical, physical and mechanical cues to the cells in three dimensions thus promoting regeneration. Herein, we have developed two synthetically designed novel tetramer peptide biomaterials. These peptides are self-assembling into a nanofibrous 3D network, entrapping 99.9% water and mimicking the native collagen of an extracellular matrix. Different biocompatibility assays including MTT, 3D cell viability assay, cytotoxicity assay and live-dead assay confirm the biocompatibility of these peptide hydrogels for mouse myoblast cells (C2C12). Immunofluorescence analysis of cell-laden hydrogels revealed that the proliferation of C2C12 cells was well-aligned in the peptide hydrogels compared to the alginate-gelatin control. These results indicate that these peptide hydrogels are suitable for skeletal muscle tissue engineering. Finally, we tested the printability of the peptide bioinks using a commercially available 3D bioprinter. The ability to print these hydrogels will enable future development of 3D bioprinted scaffolds containing skeletal muscle myoblasts for tissue engineering applications.
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