A multi-channel collagen conduit with aligned Schwann cells and endothelial cells for enhanced neuronal regeneration in spinal cord injury.

Traumatic spinal cord injury (SCI) leads to Wallerian degeneration and the accompanying disruption of vasculature leads to ischemia, which damages motor and sensory function. Therefore, understanding the biological environment during regeneration is essential to promote neuronal regeneration and overcome this phenomenon. The band of Büngner is a structure of an aligned Schwann cell (SC) band that guides axon elongation providing a natural recovery environment.

FeS-incorporated 3D PCL scaffold improves new bone formation and neovascularization in a rat calvarial defect model.

199Three-dimensional (3D) scaffolds composed of various biomaterials, including metals, ceramics, and synthetic polymers, have been widely used to regenerate bone defects. However, these materials possess clear downsides, which prevent bone regeneration. Therefore, composite scaffolds have been developed to compensate these disadvantages and achieve synergetic effects.

Advances in the development of tubular structures using extrusion-based 3D cell-printing technology for vascular tissue regenerative applications.

Until recent, there are no ideal small diameter vascular grafts available on the market. Most of the commercialized vascular grafts are used for medium to large-sized blood vessels. As a solution, vascular tissue engineering has been introduced and shown promising outcomes.

Overcome the barriers of the skin: exosome therapy.

Exosomes are nano-sized cargos with a lipid bilayer structure carrying diverse biomolecules including lipids, proteins, and nucleic acids. These small vesicles are secreted by most types of cells to communicate with each other. Since exosomes circulate through bodily fluids, they can transfer information not only to local cells but also to remote cells.

3D-printed gelatin methacrylate (GelMA)/silanated silica scaffold assisted by two-stage cooling system for hard tissue regeneration.

Among many biomaterials, gelatin methacrylate (GelMA), a photocurable protein, has been widely used in 3D bioprinting process owing to its excellent cellular responses, biocompatibility and biodegradability. However, GelMA still shows a low processability due to the severe temperature dependence of viscosity. To overcome this obstacle, we propose a two-stage temperature control system to effectively control the viscosity of GelMA.

A skeleton muscle model using GelMA-based cell-aligned bioink processed with an electric-field assisted 3D/4D bioprinting.

The most important requirements of biomedical substitutes used in muscle tissue regeneration are appropriate topographical cues and bioactive components for the induction of myogenic differentiation/maturation. Here, we developed an electric field-assisted 3D cell-printing process to fabricate cell-laden fibers with a cell-alignment cue. : We used gelatin methacryloyl (GelMA) laden with C2C12 cells.

Cell-Electrospinning and Its Application for Tissue Engineering.

Electrospinning has gained great interest in the field of regenerative medicine, due to its fabrication of a native extracellular matrix-mimicking environment. The micro/nanofibers generated through this process provide cell-friendly surroundings which promote cellular activities. Despite these benefits of electrospinning, a process was introduced to overcome the limitations of electrospinning.

Three-dimensional gelatin/PVA scaffold with nanofibrillated collagen surface for applications in hard-tissue regeneration.

The surface topography of a tissue-engineered scaffold is widely known to play an essential role in bone tissue engineering applications. Therefore, the cell-to-material interaction should be considered when developing scaffolds for bone tissue regeneration. Bone is a dynamic tissue with a distinct hierarchical structure composed of mostly collagen and bioceramics.

4D Bioprinting: Technological Advances in Biofabrication.

The development of the three-dimensional (3D) printer has resulted in significant advances in a number of fields, including rapid prototyping and biomedical devices. For 3D structures, the inclusion of dynamic responses to stimuli is added to develop the concept of four-dimensional (4D) printing. Typically, 4D printing is useful for biofabrication by reproducing a stimulus-responsive dynamic environment corresponding to physiological activities.

The fabrication of uniaxially aligned micro-textured polycaprolactone struts and application for skeletal muscle tissue regeneration.

One of the most important factors in skeletal muscle tissue regeneration is the alignment of muscle cells to mimic the native tissue. In this study, we developed a PCL-based scaffold with uniaxially aligned surface topography by stretching a 3D-printed scaffold. We examined the formation of aligned patterns by stretching the samples at different temperatures and stretching rates.

Gelatin/PVA scaffolds fabricated using a 3D-printing process employed with a low-temperature plate for hard tissue regeneration: Fabrication and characterizations.

Tissue engineering aims to repair or replace damaged tissues or organs using biomedical scaffolds cultured with cells. The scaffolds composed of biomaterials should guide the cells to mature into functional tissues or organs. An ideal scaffold to regenerate hard tissues should have mechanical stability as well as biocompatibilities.

Fabrication of micro/nanoporous collagen/dECM/silk-fibroin biocomposite scaffolds using a low temperature 3D printing process for bone tissue regeneration.

Biomaterials must be biocompatible, biodegradable, and mechanically stable to be used for tissue engineering applications. Among various biomaterials, a natural-based biopolymer, collagen, has been widely applied in tissue engineering because of its outstanding biocompatibility. However, due to its low mechanical properties, collagen has been a challenge to build a desired/complex 3D porous structure with appropriate mechanical strength.

Alternately plasma-roughened nanosurface of a hybrid scaffold for aligning myoblasts.

For successful skeletal muscle tissue regeneration, inducing alignment and fusion of myoblasts into multinucleated myotubes is critical. Many studies are ongoing to induce myoblast alignment using various micro/nanopatternings on scaffold surfaces, mechanically stretching scaffolds, or aligned micro/nanofibers. In this study, we have developed a simple method to induce myoblast alignment using a modified plasma treatment on a hybrid PCL scaffold consisting of melt-printed perpendicular PCL struts and an electrospun PCL fibrous mat.

3D bioprinting and its in vivo applications.

The purpose of 3D bioprinting technology is to design and create functional 3D tissues or organs in situ for in vivo applications. 3D cell-printing, or additive biomanufacturing, allows the selection of biomaterials and cells (bioink), and the fabrication of cell-laden structures in high resolution. 3D cell-printed structures have also been used for applications such as research models, drug delivery and discovery, and toxicology.

Additive-manufactured polycaprolactone scaffold consisting of innovatively designed microsized spiral struts for hard tissue regeneration.

Three-dimensional biomedical polycaprolactone scaffolds consisting of microsized spiral-like struts were fabricated using an additive manufacturing process. In this study, various processing parameters such as applied pressure, polymer viscosity, printing nozzle-to-stage distance, and nozzle moving speed were optimized to achieve a unique scaffold consisting of spiral-like struts. Various physical and biological analyses, including the morphological structure of spirals, mechanical properties, cell proliferation, and osteogenic activities, were performed to evaluate the effect of the spirals of the scaffold.

Mechanically reinforced cell-laden scaffolds formed using alginate-based bioink printed onto the surface of a PCL/alginate mesh structure for regeneration of hard tissue.

Cell-printing technology has provided a new paradigm for biofabrication, with potential to overcome several shortcomings of conventional scaffold-based tissue regeneration strategies via controlled delivery of various cell types in well-defined target regions. Here we describe a cell-printing method to obtain mechanically reinforced multi-layered cell-embedded scaffolds, formed of micron-scale poly(ε-caprolactone) (PCL)/alginate struts coated with alginate-based bioink. To compare the physical and cellular activities, we used a scaffold composed of pure alginate (without cells) coated PCL/alginate struts as a control.

A hybrid PCL/collagen scaffold consisting of solid freeform-fabricated struts and EHD-direct-jet-processed fibrous threads for tissue regeneration.

Hybrid biomedical structures have been used widely in various tissue-regenerating materials because they effectively induce exceptional physical and cellular responses. In this study, a new hybrid process was used to design a three-dimensional (3D) biomedical hybrid scaffold with a controlled pore-structure and high mechanical strength. A melt-dispensing method was used to obtain mechanical properties and electrohydrodynamic direct-jet (EHD-DJ) printing was used to provide microsized fibrous structures for the scaffold.

Tissue engineering bioreactor systems for applying physical and electrical stimulations to cells.

Bioreactor systems in tissue engineering applications provide various types of stimulation to mimic the tissues in vitro and in vivo. Various bioreactors have been designed to induce high cellular activities, including initial cell attachment, cell growth, and differentiation. Although cell-stimulation processes exert mostly positive effects on cellular responses, in some cases such stimulation can also have a negative effect on cultured cells.