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

Abstract

Rapid construction of pre-vascular structure is highly desired for engineered thick tissue. However, angiogenesis in free-standing scaffold has been rarely reported because of limitation in growth factor (GF) supply into the scaffold. This study, for the 1st time, investigated angiogenic sprouting in free-standing two-vasculature-embedded scaffold with three different culture conditions and additional GFs. A two-core laminar flow device continuously extruded one vascular channel with human umbilical vein endothelial cells (HUVECs) and a 3 mg/ml type-1 collagen, one hollow channel, and a shell layer with 2% w/v gelatin-alginate (70:30) composite. Under the GF flowing condition, angiogenic sprouting from the HUVEC vessel had started since day 1 and gradually grew toward the hollow channel on day 10. Due to the medium flowing, the HUVECs showed elongated spindle-like morphology homogeneously. Their viability has been over 80% up to day 10. This approach could apply to vascular investigation, and drug discovery further, not only to the engineered thick tissue.

Ultrasound standing wave spatial patterning of human umbilical vein endothelial cells for 3D micro-vascular networks formation

“…Especially, the sprout length increased abruptly from day 5 to day 9. This observation was similar with the previous reports [23,62]…”

“…Hence, branching is a fundamental process that plays a critical role in the vessel network organization and functionality. For long-term survival and proper function of the engineered tissue, the vasculature networks need to meet some requirements; (i) a 3D dense network to surpass the 200 µm diffusion limit of oxygen and nutrients, (ii) branching connections to cover the maximum tissue volume, (iii) functions of angiogenesis and perfusion, (iv) implantability to target host [20][21][22][23][24].…”

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 ].…”

“… Bioprinting Method Key Aspects Advantages Disadvantages References Inkjet First bioprinting technology that has a bio-ink cartridge. Minimum droplet volume of 20 nL Low cost Easy accessibility High cell viability (>85%) Thermal actuator is potentially prone to high-temperature stress [ 13 , 14 , 15 , 16 ] Extrusion A modification of inkjet-based bioprinting that prints a cylindrical stream onto a printing surface in a continuous line Highly controlled printing structure Limited resolution (100–500 µm) Reduced cell viability [ 22 , 23 , 32 ] Laser-assisted Propels bio-ink onto the printing surface High cell viability (>95%) Fast printing speed High resolution (10–50 µm) High cost Long-term effects of laser unclear [ 11 , 20 , 21 , 33 ] Stereolithography Uses UV light to solidify bio-ink layer-by-layer Fast printing speed High resolution Excellent cell adhesion …”

Double-layered blood vessels over 3 mm in diameter extruded by the inverse-gravity technique

“…To fabricate long vasculatures with affordable systems in laboratories [38][39][40][41][42][43][44][45][46][47][48], direct extrusion techniques were developed by different research groups. The developed microfluidic devices usually induce coaxial laminar flow and simultaneously encapsulate vascular cells in hydrogels, such as decellularised extracellular matrix [49,50], type-I collagen [39], calcium alginate [51][52][53], a mixture of collagen and alginate [50,54], and customised gelatine methacryloyl (GelMA) [55].…”