Coaxial printing of double-layered and free-standing blood vessel analogues without ultraviolet illumination for high-volume vascularised tissue

Abstract

Human umbilical vein endothelial cells (HUVECs) and human aortic smooth muscle cells (HASMCs) were coaxially and continuously extruded without ultraviolet illumination using a microfluidic-based nozzle. Type I collagen (3 mg ml−1) containing HUVECs and a crosslinking reagent (100 mM CaCl2) were supplied as the core material. A mixture of 3 mg ml−1 of type I collagen (25%) and 1.8% weight volume−1 of sodium alginate (75%) was provided as the shell layer material surrounding the core material. The HUVECs were well proliferated at the core and reshaped into a monolayer formation along the axial direction of the scaffold. The HASMCs showed more than 90% cell viability in the shell layer. Fluorescent beads were passed through the inside channel of the scaffold with the HUVEC core and HASMC shell using an in-house connector. This double-layered scaffold showed higher angiogenesis in growth factor-free medium than the scaffold with only a HUVEC core. The HASMCs in the shell layer affected angiogenesis, extracellular matrix secretion, and outer diameter. The proposed technique could be applied to three-dimensional bioprinting for the production of high-volume vascularised tissue.

Angiogenesis in Free-Standing Two-Vasculature-Embedded Scaffold Extruded by Two-Core Laminar Flow Device

“…Confocal images of the HUVEC core exhibited a hollow center in cross-section view ( Figure 5F ). HUVEC has the propensity to form luminal structures in the three-dimensional matrix[ 22 ], which can be perfused[ 18 , 22 , 23 ].…”

“…Duong et al . extruded the double-layered single-vascular scaffold with human umbilical vein endothelial cell (HUVEC) and human aortic smooth muscle cell (HASMC)[ 18 ]. In their investigation, the GF secreted from the HASMC layer-induced angiogenic sprouting.…”

Acoustic Cell Patterning in Hydrogel for Three-Dimensional Cell Network Formation

“…Cell viability was determined using a ratio calculation between the mean grey value (gv) of 2 color channels (green for live cells and red for dead cells) on a black background. The grey values were obtained from 10× confocal images, which were split into 2 separate color channels using ImageJ 1.51 h. The calculation was carried out according to the following equation [21,24]:…”

“…An alternative method was proposed by Kang et al, using layer-by-layer three-dimensional liquid bioink printing to construct a cell-laden scaffold that embedded hollow network structures [16] (albeit not a vascularized network). Another bio-printing method applying co-axial laminar flows enabled researchers to continuously extrude cell-laden structures of a single-conduit geometry, but not in a network format [8,[17][18][19][20][21]. Even though the pioneering work on the above methods inspired studies on vascularized networks, these were not appropriate for the recently developed bio-printing techniques, since they stacked pre-fabricated cell-laden layers with the requirement of a precise alignment.…”

3D Bioprinting for Next-Generation Personalized Medicine

“…Extrusion-based bioprinting is a modification of inkjet printing that exerts a constant force on the bio-ink during output [ 21 ]. This results in a cylindrical printed stream that attaches to the intended surface as a continuous line [ 22 , 23 ]. This is a significantly different approach to the singular, high-cell-density, bio-ink droplets found in standard inkjet bioprinting [ 24 ].…”