Automated Robotic Dispensing Technique for Surface Guidance and Bioprinting of Cells

Abstract

This manuscript describes the introduction of cell guidance features followed by the direct delivery of cells to these features in a hydrogel bioink using an automated robotic dispensing system. The particular bioink was selected as it allows cells to sediment towards and sense the features. The dispensing system bioprints viable cells in hydrogel bioinks using a backpressure assisted print head. However, by replacing the print head with a sharpened stylus or scalpel, the dispensing system can also be employed to create topographical cues through surface etching. The stylus movement can be programmed in steps of 10 µm in the X, Y and Z directions. The patterned grooves were able to orientate mesenchymal stem cells, influencing them to adopt an elongated morphology in alignment with the grooves' direction. The patterning could be designed using plotting software in straight lines, concentric circles, and sinusoidal waves. In a subsequent procedure, fibroblasts and mesenchymal stem cells were suspended in a 2% gelatin bioink, for bioprinting in a backpressure driven extrusion printhead. The cell bearing bioink was then printed using the same programmed coordinates used for the etching. The bioprinted cells were able to sense and react to the etched features as demonstrated by their elongated orientation along the direction of the etched grooves.

Machine Assisted Experimentation of Extrusion-Based Bioprinting Systems

“…In particular, the general trends of increased extrusion pressure and alginate concentration resulting in decreased cell viability prediction values correlates with findings in previous literature that indicate increasing alginate concentration results in decreased cell viability [21][22][23]. In other cases, trends of predicted values oppose what is seen in the literature [24,25]. These trends include: (1) decreased cell viability with increasing nozzle diameter, (2) increased cell viability with increasing gelatin concentration, and (3) larger filament diameter in DMEM-based bioink compared to saline solution-based bioink.…”

Contact guidance for cardiac tissue engineering using 3D bioprinted gelatin patterned hydrogel

“…Additive manufacturing techniques or 3D printing have emerged as useful approaches in tissue engineering to fabricate cell supporting scaffolds [11]. Indeed, 3D printing has been shown to generate features that influence the behavior of the seeded cells such as the printing of cell aligning features [12][13][14]. Such 3D printed cell aligning grooves and channels are usually fabricated from stiff synthetic polymers by extruding the polymer in a molten state or dissolved in volatile solvents, thus allowing rapid post deposition setting through cooling or solvent evaporation, respectively [15].…”

A bench‐top molding method for the production of cell‐laden fibrin micro‐fibers with longitudinal topography

“…The method consists of four main steps: (a) the injection of the fibrin components including the cells into the silicone tube, (b) the gelation process, (c) the ejection of the gel after polymerization and (d) the stretching of the resulting fiber. We expect that already existing solutions for automated pipetting, handling, collection, gripping of samples and controlled linear displacement could be assembled to create an ad‐hoc automated system for the production of the fibers in a sterile, closed environment (Bhuthalingam, Lim, Irvine, & Venkatraman, ; Bartolo, Domingos, Gloria, & Ciurana, ; P. F. Costa et al, ; Kikuchi et al, ; Mekhileri et al, ). A GMP conform production is facilitated by the limited number of parts in contact with the materials composing the fibers and the commercial availability of GMP‐conform cell‐work stations.…”