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Creation of a vascular system for organ manufacturing

Figure 2. Several bioprinters made in Tsinghua Unversity, Prof. X Wang’s group. (A) Hepatocyte and adipose-derived stem cell
(ADSC) assembling based on the first generation of cell assembling technique [40–51] . (B) Cell assembling based on a two syringe RP
technique.Two different cell types in the gelatin-based hydrogels can be assembled simultaneously into a construct [52,53] . (C) A
double-nozzle, low-temperature deposition manufacturing (DLDM) technique. An elliptical hybrid hierarchical polyurethane and
cell/hydrogel construct was fabricated using the DLDM system [56–63] . (D) A schematic description of the modeling and manufacturing
processes of four liver lobe-like constructs with a four-nozzle low-temperature deposition manufacturing (FLDM) bioprinting sys-
tem [10] .

turing, such as the heart, the liver, and breast, have building block approach was used to print multi-
been successfully designed and printed (Figure 2(D)). channel 3D organ regenerative scaffolds [56–63] . With
We have published more than 110 research articles this technique, a specific model was selected via CAD
and 40 patents with these bioprinting techniques. In and solid free form fabrication processes were con-
addition, the first combined multi-nozzle 3D printer ducted under computer’s directions.
has also been developed in our group and a viable liv- Hybrid hierarchical polyurethane (PU)-cell/hydro-
er substitute with various branching functional chan- gel constructs were automatically created using a
nels has been printed. These RP techniques have be- double-nozzle, low-temperature deposition device based
come the most convenient and reliable techniques for on the layer-by-layer manufacturing principle [62,63] . The
the manufacturing of complex organs, including the elastomeric PU, mainly based on polycaprolactone
vascular trees, in the coming years. and poly(ethylene glycol) with excellent biocompati-
bility and tunable biodegradation properties, was used
3.2 A Low-Temperature Deposition Manufacturing
(LDM) Technology as a supportive template for cell/hydrogel accommo-
dation, growth, immigration and proliferation. Bio-
Particularly, in order to generate complex organs with reactors can be applied for pulsatile cultures of the 3D
adequately strong mechanical properties and hierar- vascular templates with the principal axis. Further
chical structures, we have developed a series of LDM researches are carried out for stem cell engagement in
technologies to process various biomaterials under a the construct for a real vascular system.
temperature ~ –20℃. Both synthetic and natural po-
lymers, including cells, can be designed and fabricated 3.3 Several Examples Made from the LDM
Technology
into complex 3D objects with an intrinsic network of
interconnected channels (Figure 2(C) and 2(D)). A A primary branched vascular template, made of syn-

80 International Journal of Bioprinting (2015)–Volume 1, Issue 1