It is unique easy-to-control method of bioprinting to create more flexible and complex 3D construct by changing the line width during one printing path. The dragging technique uses the stretching phenomenon when viscoelastic material is dispensed throughout the printing nozzle. We proposed and fabricated a unique 3D printing method called by the dragging technique. This technology can produce free-form structures, unlike electro-spinning technology. Thus, technical limitations exist that preclude composition of free-form constructs such as the esophageal mucosa and muscle layers.Įxtrusion-based 3D bioprinting has been extensively studied to enable the production of the tubular free-form construct in tissue engineering 19, 20. However, since the use of a rotating mandrel is an essential element for the manufacture of tubular construct, the shape and size of the tubular construct were determined by a rotating mandrel.
For this reason, electrospinning has been actively applied to esophagus tissue engineering. Electrospinning was considered a promising technology because it can recapitulate microstructures mimicking the environment of the extracellular matrix (ECM) in native tissue. However, these studies focused on fabricating an epithelial layer, and lacked the multi-layered hierarchical structure of the esophagus.Įlectrospinning and extrusion-based 3D bioprinting technology have been used to fabricate tubular constructs for esophageal regeneration 14, 15, 16, 17, 18. Previous studies have used the porcine bladder-derived dECM sheet 10, 11, collagen sheet 8, 12, and silicone meshes 13, 14. Several approaches were considered to fabricate tubular constructs for esophageal tissueengineering.
Therefore, it is necessary to develop esophageal tissueengineering that enables regeneration of esophageal mucosa and muscle layers. Human esophageal tissue consists of the mucosa, submucosa, and muscular layers. Therefore, a tissue engineering-based approach has been proposed as a promising alternative for reconstruction of circumferential esophageal defects 7, 8, 9. Unfortunately, surgical resection and ablation can cause postoperative complications and various surgical morbidities 4, 5, 6.
#Why is construct 3 free limited to 2 layers skin#
Congenital or acquired esophageal disorders such as esophageal cancer, malignancy, and esophageal achalasia usually require reconstruction of the defect site after the surgery and stomach, small and large intestine, and skin tissues are used to repair the esophagus tissues 1, 2, 3. The esophageal tissue refers to the hollow organ between the oropharynx and the stomach, which allows food to pass to the stomach through peristalsis. This structure can be applied to full-thickness circumferential esophageal defects and esophageal regeneration. The two types of esophageal tissue derived-decellularized extracellular matrix bioinks can mimic the inherent components and composition of original tissues with layer specificity. Based on this suggested technique, we developed a bioprinted 3D esophageal structure with multi-layered features and converged with biochemical microenvironmental cues of esophageal tissue by using decellularizedbioinks from mucosal and muscular layers of native esophageal tissues. In this study, we developed a extrusion-based 3D printing technique to control the size and the shape of the pore in a single extrusion process, so that the fabricated structure has a higher flexibility than that fabricated in the conventional process. 3D bioprinting is known as a suitable method to fabricate complex free-form tubular structures with desired pore characteristic. However, the fabrication techniques are nearly limited to creating only cylindrical outer shapes with the help of additional apparatus (e.g., mandrels for electrospinning) and are unable to recapitulate multi-layered characteristic or complex-shaped inner architectures. To date, polymer-based esophageal substitutes have been studied as an alternative. Surgeons usually use ectopic conduit tissues including stomach and intestine, presumably inducing donor site morbidity and severe complications. There are no commercialized off-the-shelf alternatives to current esophageal reconstruction and regeneration methods. The incidences of various esophageal diseases (e.g., congenital esophageal stenosis, tracheoesophageal fistula, esophageal atresia, esophageal cancer) are increasing, but esophageal tissue is difficult to be recovered because of its weak regenerative capability.
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