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3D bioprinting is an advanced manufacturing technology that utilizes biomaterials and bioactive components to manufacture artificial tissues and organs. It has been widely applied in multiple medical fields and possesses outstanding advantages in organ reconstruction. In recent years, 3D bioprinted organs have made an array of groundbreaking achievements. Nevertheless, it is still in the exploratory stage of research and development and still has bottleneck problems, which can not be applied in organ transplantation in vivo. In this article, the application of 3D printing technology in medicine, characteristics of 3D bioprinting technology, research hotspots and difficulties in bionic structure, functional reconstruction and immune response of 3D bioprinted organs, and the latest research progress on 3D bioprinting technology were illustrated, and the application prospect of 3D bioprinting technology in the field of organ reconstruction was elucidated, aiming to provide novel ideas for the research and clinical application of organ reconstruction and artificial organ reconstruction, and promote the development of organ transplantation and individualized medicine.
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Three-dimensional(3D)extrusion-based bioprinting is widely used in tissue engineering and regener-ative medicine to create cell-incorporated constructs or scaffolds based on the extrusion technique.One critical issue in 3D extrusion-based bioprinting is printability or the capability to form and maintain reproducible 3D scaffolds from bioink(a mixture of biomaterials and cells).Research shows that printability can be affected by many factors or parameters,including those associated with the bioink,printing process,and scaffold design,but these are far from certain.This review highlights recent de-velopments in the printability assessment of extrusion-based bioprinting with a focus on the definition of printability,printability measurements and characterization,and printability-affecting factors.Key issues and challenges related to printability are also identified and discussed,along with approaches or strategies for improving printability in extrusion-based bioprinting.
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At present, trachea reconstruction by tissue engineering technology of 3D bio-printing has become an ideal method for repairing long-segment trachea after injury, and how to select printing materials to manufacture appropriate tissue engineering trachea is the key to ensure the perfect survival of trachea grafts in the human body. Bioink is a cellular formula containing bioactive ingredients that could make or break the 3D printed tissue-engineered trachea. It is particularly important to find a bio-ink that has good biocompatibility and can print biological structures with high mechanical strength. This paper aims to review the advantages and disadvantages of bio-ink made of different materials, current application status and clinical application of 3D printed tissue-engineered trachea, so as to promote the clinical transformation of tissue-engineered trachea as soon as possible and put into practical clinical application systematically.
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Decellularized extracellular matrix (dECM), which contains many proteins and growth factors, can provide three-dimensional scaffolds for cells and regulate cell regeneration. 3D bioprinting can print the combination of dECM and autologous cells layer by layer to construct the tissue structure of carrier cells. In this paper, the preparation methods of tissue and organ dECM bioink from different sources, including decellularization, crosslinking, and the application of dECM bioink in bioprinting are reviewed, with future applications prospected.
Subject(s)
Bioprinting , Extracellular Matrix , Printing, Three-Dimensional , Tissue Engineering , Tissue ScaffoldsABSTRACT
A plethora of organic pollutants such as pesticides, polycyclic and halogenated aromatic hydrocarbons, and emerging pollutants, such as flame retardants, is continuously being released into the environment. This poses a huge threat to the society in terms of environmental pollution, agricultural product quality, and general safety. Therefore, effective removal of organic pollutants from the environment has become an important challenge to be addressed. As a consequence of the recent and rapid developments in additive manufacturing, 3D bioprinting technology is playing an important role in the pharmaceutical industry. At the same time, an increasing number of microorganisms suitable for the production of biomaterials with complex structures and functions using 3D bioprinting technology, have been identified. This article briefly discusses the principles, advantages, and disadvantages of different 3D bioprinting technologies for pollutant removal. Furthermore, the feasibility and challenges of developing bioremediation technologies based on 3D bioprinting have also been discussed.
Subject(s)
Biocompatible Materials , Biodegradation, Environmental , Bioprinting , Environmental Pollutants , Technology , Tissue EngineeringABSTRACT
BACKGROUND: Diffusion tensor imaging, as a relatively new method based on MRI, has become an important means of examination and diagnosis in the field of neuroimaging. OBJECTIVE: To investigate the role of using diffusion tensor tensor imaging data to predict 3D-bioprinted collagen/silk fibroin scaffolds in the locomotor function recovery after spinal cord injury. METHODS: Ordinary and 3D-bioprinted collagen/silk fibroin scaffold were prepared. Forty adult female SD rats provided by the Laboratory Animal Center of the Academy of Military Medical Sciences of the People’s Liberation Army were randomly divided into four groups with 10 rats in each group. In the sham operation group, only T10 vertebral plate was removed. In the model group, spinal cord injury was induced by total transection of spinal cord at T10 segment. In the ordinary collagen scaffold and 3D-printed scaffold groups, after induction of T10 spinal cord injury, ordinary collagen scaffold and 3D-printed scaffold were implanted, respectively. At 1, 2, 3, 4, 6 and 8 weeks after surgery, Basso, Beattie and Bresnahan (BBB) locomotor function scoring and oblique plate test of the hind limbs were carried out. At 8 weeks after surgery, electrophysiological test of the hind limbs was performed to evaluate locomotor function. At 8 weeks after surgery, diffusion tensor imaging of the lumbar spine was performed and the correlation between diffusion tensor imaging parameter and rat locomotor function was analyzed. Animal experiments were approved by the Animal Ethics Committee of Characteristic Medical Center of the Chinese people’s Armed Police Force (approval No. 27653/58). RESULTS AND CONCLUSION: (1) From 3 weeks after surgery, BBB score in the 3D-printed group was significantly higher than that in the model and ordinary collagen scaffold groups (P < 0.05 or P < 0.01). From 2 weeks after surgery, the slope angle in the 3D-printed scaffold group was significantly higher than that in the model and ordinary scaffold groups (P < 0.05 or P < 0.01). (2) The amplitude of motor evoked potential in the 3D-printed scaffold group was significantly greater than that in the model and ordinary collagen scaffold groups (P < 0.05 or P < 0.01). The latency of motor evoked potential in the 3D-printed scaffold group was significantly shorter than that in the model and ordinary collagen scaffold groups (P < 0.05 or P < 0.01). (3) Diffusion tensor imaging showed that the nerve fiber trajectories in the three groups were irregular and lacked the continuity of nerve fibers, but the number of regenerated nerve fiber bundles in the 3D-printed collagen scaffold group was greater than that in the model and ordinary collagen scaffold groups (P < 0.01). The fractional anisotropy at 9, 7.5, 4.5, -3, -6, -7.5, -9 mm from the center of spinal cord injury in 3D-printed collagen scaffold group was significantly higher than that in model and ordinary collagen scaffold groups (P < 0.05 or P < 0.01). (4) The BBB score, slope angle, amplitude of motor evoked potential, latency of motor evoked potential were positively correlated with the fractional anisotropy value of diffusion tensor imaging from head to tail of rats. (5) These results suggest that diffusion tensor imaging can be used as an effective predictor to evaluate the recovery of neurological function after spinal cord injury in experimental animals and clinical cases.
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BACKGROUND@#The shortage of donor corneas is a severe global issue, and hence the development of corneal alternatives is imperative and urgent. Although attempts to produce artificial cornea substitutes by tissue engineering have made some positive progress, many problems remain that hamper their clinical application worldwide. For example, the curvature of tissue-engineered cornea substitutes cannot be designed to fit the bulbus oculi of patients.@*OBJECTIVE@#To overcome these limitations, in this paper, we present a novel integrated three-dimensional (3D) bioprinting-based cornea substitute fabrication strategy to realize design, customized fabrication, and evaluation of multi-layer hollow structures with complicated surfaces.@*METHODS@#The key rationale for this method is to combine digital light processing (DLP) and extrusion bioprinting into an integrated 3D cornea bioprinting system. A designable and personalized corneal substitute was designed based on mathematical modelling and a computer tomography scan of a natural cornea. The printed corneal substitute was evaluated based on biomechanical analysis, weight, structural integrity, and fit.@*RESULTS@#The results revealed that the fabrication of high water content and highly transparent curved films with geometric features designed according to the natural human cornea can be achieved using a rapid, simple, and low-cost manufacturing process with a high repetition rate and quality.@*CONCLUSIONS@#This study demonstrated the feasibility of customized design, analysis, and fabrication of a corneal substitute. The programmability of this method opens up the possibility of producing substitutes for other cornea-like shell structures with different scale and geometry features, such as the glomerulus, atrium, and oophoron.
Subject(s)
Humans , Artificial Organs , Bioprinting , Cornea/cytology , Models, Theoretical , Printing, Three-Dimensional , Tensile Strength , Tissue Engineering/methods , Tissue ScaffoldsABSTRACT
Background: The shortage of donor corneas is a severe global issue, and hence the development of corneal alternatives is imperative and urgent. Although attempts to produce artificial cornea substitutes by tissue engineering have made some positive progress, many problems remain that hamper their clinical application worldwide. For example, the curvature of tissue-engineered cornea substitutes cannot be designed to fit the bulbus oculi of patients. Objective: To overcome these limitations, in this paper, we present a novel integrated three-dimensional (3D) bioprinting-based cornea substitute fabrication strategy to realize design, customized fabrication, and evaluation of multi-layer hollow structures with complicated surfaces. Methods: The key rationale for this method is to combine digital light processing (DLP) and extrusion bioprinting into an integrated 3D cornea bioprinting system. A designable and personalized corneal substitute was designed based on mathematical modelling and a computer tomography scan of a natural cornea. The printed corneal substitute was evaluated based on biomechanical analysis, weight, structural integrity, and fit. Results: The results revealed that the fabrication of high water content and highly transparent curved films with geometric features designed according to the natural human cornea can be achieved using a rapid, simple, and low-cost manufacturing process with a high repetition rate and quality. Conclusions: This study demonstrated the feasibility of customized design, analysis, and fabrication of a corneal substitute. The programmability of this method opens up the possibility of producing substitutes for other cornea-like shell structures with different scale and geometry features, such as the glomerulus, atrium, and oophoron.
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BACKGROUND: The tissue engineering and regenerative medicine approach require biomaterials which are biocompatible, easily reproducible in less time, biodegradable and should be able to generate complex three-dimensional (3D) structures to mimic the native tissue structures. Click chemistry offers the much-needed multifunctional hydrogel materials which are interesting biomaterials for the tissue engineering and bioprinting inks applications owing to their excellent ability to form hydrogels with printability instantly and to retain the live cells in their 3D network without losing the mechanical integrity even under swollen state. METHODS: In this review, we present the recent developments of in situ hydrogel in the field of click chemistry reported for the tissue engineering and 3D bioinks applications, by mainly covering the diverse types of click chemistry methods such as Diels–Alder reaction, strain-promoted azide-alkyne cycloaddition reactions, thiol-ene reactions, oxime reactions and other interrelated reactions, excluding enzyme-based reactions. RESULTS: The click chemistry-based hydrogels are formed spontaneously on mixing of reactive compounds and can encapsulate live cells with high viability for a long time. The recent works reported by combining the advantages of click chemistry and 3D bioprinting technology have shown to produce 3D tissue constructs with high resolution using biocompatible hydrogels as bioinks and in situ injectable forms. CONCLUSION: Interestingly, the emergence of click chemistry reactions in bioink synthesis for 3D bioprinting have shown the massive potential of these reaction methods in creating 3D tissue constructs. However, the limitations and challenges involved in the click chemistry reactions should be analyzed and bettered to be applied to tissue engineering and 3D bioinks. The future scope of these materials is promising, including their applications in in situ 3D bioprinting for tissue or organ regeneration.
Subject(s)
Biocompatible Materials , Bioprinting , Click Chemistry , Cycloaddition Reaction , Hydrogels , Hydrogels , Ink , Regeneration , Regenerative Medicine , Tissue EngineeringABSTRACT
Rapid progress in tissue engineering research in past decades has opened up vast possibilities to tackle the challenges of generating tissues or organs that mimic native structures. The success of tissue en-gineered constructs largely depends on the incorporation of a stable vascular network that eventually anastomoses with the host vasculature to support the various biological functions of embedded cells. In recent years, significant progress has been achieved with respect to extrusion, laser, micro-molding, and electrospinning-based techniques that allow the fabrication of any geometry in a layer-by-layer fashion. Moreover, decellularized matrix, self-assembled structures, and cell sheets have been explored to replace the biopolymers needed for scaffold fabrication. While the techniques have evolved to create specific tissues or organs with outstanding geometric precision, formation of interconnected, functional, and perfused vascular networks remains a challenge. This article briefly reviews recent progress in 3D fab-rication approaches used to fabricate vascular networks with incorporated cells, angiogenic factors, proteins, and/or peptides. The influence of the fabricated network on blood vessel formation, and the various features, merits, and shortcomings of the various fabrication techniques are discussed and summarized.