Stimulus-assisted in situ bioprinting: advancing direct bench-to-bedside delivery.

The fabrication of 3D bioconstructs using bioprinters will advance the field of regenerative medicine owing to its ability to facilitate clinical treatments. Additional stimulations have been applied to the bioconstructs to guide cells laden in the bioconstructs. However, the conventional bench-to-bedside delivery based on separate bioprinting and biostimulating processes may increase the risks of contamination and shape discordance owing to the considerably long process involved.

Bioprinted hASC-laden collagen/HA constructs with meringue-like macro/micropores.

Extrusion-based bioprinting is one of the most effective methods for fabricating cell-laden mesh structures. However, insufficient cellular activities within the printed cylindrical cell-matrix blocks, inducing low cell-to-cell interactions due to the disturbance of the matrix hydrogel, remain to be addressed. Hence, various sacrificial materials or void-forming methods have been used; however, most of them cannot solve the problem completely or require complicated fabricating procedures.

ASC/chondrocyte-laden alginate hydrogel/PCL hybrid scaffold fabricated using 3D printing for auricle regeneration.

Tissue engineering using adipose derived stem cells (ASCs) has become one of the most promising treatments for defective articular cartilage owing to the stability and dynamic differentiation of ASCs. In this study, we fabricated a 3D hybrid scaffold using poly(ε-caprolactone) (PCL) to support the mechanical properties of the regenerating auricle cartilage, and injected a cell-laden alginate hydrogel, containing a mixture of ASCs and chondrocytes, into the PCL scaffold. Using the cell-laden 3D auricle structure, the in vitro chondrogenesis of the ASCs with and without the presence of chondrocytes was examined.

Fabrication of Mechanically Reinforced Gelatin/Hydroxyapatite Bio-Composite Scaffolds by Core/Shell Nozzle Printing for Bone Tissue Engineering.

In tissue engineering, biocompatible scaffolds are used as 3D cell niches to provide a similar environment to that of native tissue for seeded cells to regenerate the target tissue. When engineering bone tissue, high mechanical strength and calcium phosphate composition are essential factors to consider. In this study, we fabricated biocompatible composite scaffolds composed of synthetic polymers (polycaprolactone (PCL) and poly (vinyl alcohol) (PVA)), natural polymers (gelatin and collagen) and bioceramic (hydroxyapatite; HA) for bone tissue engineering.

Innovative Cryopreservation Process Using a Modified Core/Shell Cell-Printing with a Microfluidic System for Cell-Laden Scaffolds.

This work investigated the printability and applicability of a core/shell cell-printed scaffold for medium-term (for up to 20 days) cryopreservation and subsequent cultivation with acceptable cellular activities including cell viability. We developed an innovative cell-printing process supplemented with a microfluidic channel, a core/shell nozzle, and a low-temperature working stage to obtain a cell-laden 3D porous collagen scaffold for cryopreservation. The 3D porous biomedical scaffold consisted of core/shell struts with a cell-laden collagen-based bioink/dimethyl sulfoxide mixture in the core region and an alginate/poly(ethylene oxide) mixture in the shell region.

Development of a tannic acid cross-linking process for obtaining 3D porous cell-laden collagen structure.

Cell-printing is an emerging technique that enables to build a customized structure using biomaterials and living cells for various biomedical applications. In many biomaterials, alginate has been widely used for rapid gelation, low cost, and relatively high processability. However, biocompatibilities enhancing cell adhesion and proliferation were limited, so that, to overcome this problem, an outstanding alternative, collagen, has been extensively investigated.

New strategy for enhancing in situ cell viability of cell-printing process via piezoelectric transducer-assisted three-dimensional printing.

Tissue engineering has become one of the great applications of three-dimensional cell printing because of the possibility of fabricating complex cell-laden scaffolds. Three typical methods (inkjet, micro-extrusion, and laser-assisted bio-printing) have been used to fabricate structures. Of these, micro-extrusion is a comparatively easy method, but has some drawbacks such as low in situ cell viability after fabricating cell-laden structures because of the high wall shear stress in micro-sized nozzles.