Page 269 - IJB-9-2

International Journal of Bioprinting Bioprinting of β-islet-like constructs

Figure 2. Bioartificial pancreatic islets. (A) PEC-Encap device, created by ViaCyte, committed pancreatic endoderm cells derived from human embry-
onic stem cells encapsulated in an immunoprotective membrane that can diffuse oxygen and glucose to induce insulin and glucagon secretion into the
blood circulation. (B) Schematic view of different bioprinting approaches to creating pancreatic constructs. (C) Schematic view of coaxial extrusion bio-
printing method that provides the possibility of bioprinting of pancreatic islets or insulin-producing cells in the core and supportive cells in the shell of
extruded strands.
Table 2. Comparison of bioprinting approaches

Bioprinting techniques Viscosity/Material Resolution Printing speed Postprinting viability References
Material jetting Low/ 10–200 μm Fast High [67,70]
Hydrogel: Alginate, agarose, gelatin, collagen,
fibrin, HA, GelMA, PEG
Vat polymerization Low-High/ Photoinitiator and photopolymer 5–100 μm Fast High [76,77]
GelMA, HAMA, PEGDA
Material extrusion High/ 15–400 μm Slow Medium [81–83]
Hydrogel: Alginate, agarose, gelatin, collagen,
fibrin, HA, GelMA, PEG
HA, hyaluronic acid; GelMA, gelatin methacrylate acid; PEG, polyethylene glycol; HAMA, hyaluronic acid methacrylate; PEGDA, polyethylene diacrylate.
is composed of both acinar and ductal cells by using laser- form and subsequently solidified using photo-crosslinking,
assisted bioprinting techniques for the study of factors that temperature, or pH phase transition. The postprint structural
contribute to the formation and progression of pancreatic integrity depends on the ratio between a hydrogel and cells
ductal adenocarcinoma. Although LIFT is a generally within the hydrogel. The mechanical strength increases with
excellent method, the droplet size tends to be much smaller the amount of hydrogel used, although the viability is little
than those of inkjet printers; therefore, the print time is without the cellular component. Typically used hydrogels are
increased, and more droplets are required to cover the naturally derived, including proteins and polysaccharides,
same area . Hydrogels are used as a printing medium in such as collagen, gelatin, fibrinogen, chitosan, and alginate
[75]
material jetting systems. They are printed in their hydrous (Figure 2B and Table 2) .
[70]

Volume 9 Issue 2 (2023) 261 http://doi.org/10.18063/ijb.v9i2.665