Rational Design of a Triple-Layered Coaxial Extruder System: in silico and in vitro Evaluations Directed Toward Optimizing Cell Viability

Abstract

Biofabrication is a rapidly evolving field whose main goal is the manufacturing of three-dimensional (3D) cell-laden constructs that closely mimic tissues and organs. Despite recent advances on materials and techniques directed toward the achievement of this goal, several aspects such as tissue vascularization and prolonged cell functionality are limiting bench-to-bedside translation. Extrusion-based 3D bioprinting has been devised as a promising biofabrication technology to overcome these limitations, due to its versatility and wide availability. Here, we report the development of a triple-layered coaxial nozzle for use in the biomanufacturing of vascular networks and vessels. The design of the coaxial nozzle was first optimized toward guaranteeing high cell viability upon extrusion. This was done with the aid of in silico evaluations and their subsequent experimental validation by investigating the bioprinting of an alginate-based bioink. Results confirmed that the values for pressure distribution predicted by in silico experiments resulted in cell viabilities above 70% and further demonstrated the effect of layer thickness and extrusion pressure on cell viability. Our work paves the way for the rational design of multi-layered coaxial extrusion systems to be used in biofabrication approaches to replicate the very complex structures found in native organs and tissues.

Bioprinting: A Strategy to Build Informative Models of Exposure and Disease

“…The adaptability and versatility of EBB enable the incorporation of a great number of combinations of bioinks/biomaterial inks/cross-linking strategies for extrusion. Coaxial bioprinting being either bi-, tri-or tetra-layered [189], [220], [221] allows the concentric and simultaneous extrusion of multiple materials. Indeed, the fabrication of hollow tubes that function as vasculature [190], [222], [223] has taken advantage of sacrificial biomaterial inks such as alginate or Pluronic® F-127.…”

Advances in Coaxial Additive Manufacturing and Applications

“…Silva et al. [ 40 ] also used a computationally aided design model to analyze three triple‐layered coaxial nozzle designs differing from the diameter of each of the three channels ( d inner / d middle / d outer = 23G (Gauge)/18G/14G; 25G/18G/14G; 20G/15G/13G) in order to optimize the cell viability in biofabrication applications. Using COMSOL Multiphysics, the authors performed simulations to determine the fluid velocity and the pressure distribution within each of the channel of the nozzle.…”

“…Silva et al. [ 40 ] chose to follow a different approach to fabricate single‐layered hollow tubular structures of different dimensions. Indeed, they focused their work on tri‐material coaxial AM of vascular networks.…”

“…Silva et al [40] chose to follow a different approach to fabricate single-layered hollow tubular structures of different Manufacturing process of vascular alginate coil: i) printing of hollow fibers, ii) partial cross-linking of fibers, iii) printing cell-laden tubes over a cylinder, iv) creating a layer of fibroblasts-laden tubes over the previous one, v) placing the fabricated tubular coil in CaCl 2 solution, vi) ejection of collagen solution, vii) passing endothelial cells into the coil; b) morphology of the 3D printed vascular coil i) optical image of a single-layer and a double-layer coil, ii,iii) cross-sections and close up views. c) Potential vascular network applications: i) vascular networks with branches, ii) vascular circulation system, iii) perfusion of cell culture media through the vascular circulation system.…”

Supramolecular Biopolymers for Tissue Engineering

“…To overcome these limitations, different techniques like material extrusion [172,173], material jetting [174][175][176], and vat polymerization [177,178] (which encompasses stereolithography and two-photon polymerization) [179] were introduced. In addition, novel innovative methods have been developed such as, for instance, computed axial lithography, better known as volumetric printing, with the aim to print photocrosslinkable polymers faster and with better resolution [180].…”