Photocrosslinkable Materials for the Fabrication of Tissue-Engineered Constructs by Stereolithography - Tissue Engineering: Computer Modeling, Biofabrication and Cell Behavior - page 160

Fig. 11 Fluorescence confocal microscopy of PEGDA hydrogel scaffolds produced with pre-de-
fined spatial-pattern in a single layer ( A ) and multi-layered scaffolds ( B , C ) containing either FITC
or Cy5-labeled polystyrene particles [ 63 ]
of biomaterials and cells with precise spatial arrangement. Arcaute et al. [ 2 - 4 ]ex-
plored stereolithography for fabricating multi-material spatially controlled bioactive
scaffolds. To accomplish multi-material fabrication, a mini-vat setup was designed,
allowing for self-aligning X-Y registration during fabrication. The mini-vat setup
allowed the construct to be easily removed and rinsed, and different photocrosslink-
able solutions to be easily removed and added to the vat. Multi-material scaffolds
were fabricated by including controlled concentrations of fluorescently labeled dex-
tran, fluorescently labeled bioactive PEG or bioactive PEG in different regions of
the scaffold (Fig. 12 ). Human dermal fibroblast cells were seeded on top of the
fabricated scaffolds. Spatial control was successfully showed in features down to
500 µm.
Ovsianikov et al. [ 81 ] combined the 2PP technique and the laser-induced for-
ward transfer (LIFT) process to produce 3D multicellular tissue constructs. The 2PP
technique was employed for the fabrication of PEGDA scaffolds, which were sub-
sequently seeded with vascular smooth muscle-like cells (within the outer scaffold
area) and endothelial cells (into the inner scaffold area), using the LIFT process.
To allow the fabrication of 3D constructs containing multiple hydrogel composi-
tions and cell types with control over the spatial distribution of cells and bioactive
molecules, Chan et al. [ 24 ] modified a conventional stereolithographic apparatus.
These authors showed the production of PEGDA constructs with encapsulated/3T3
cells through the manual addition of individual layers of cell-containing photopoly-
mer, preventing the cells settling to the bottom of the stereolithographic vat due to
gravity.
Zorlutuna et al. [ 115 ] used stereolithography to produce spatially organized 3D
co-culture of multiple cell types to investigate cell-cell interaction and the microen-
vironments of complex tissues. Two layer-constructs, using different cell types and
hydrogels, were produced as shown in Fig. 13 . The first layer was produced by poly-
merizing poly(ethylene glycol) methyl ether methacrylate (PEGMA3400) contain-
ing adipose-derived stem cells (ASCs), while the second layer contains primary hip-
pocampus neurons (HNs) and skeletal muscle myoblast (MCs) cells encapsulated in
oxidized methacrylic alginate and poly(ethylene glycol) methyl ether methacrylate
1100 (OMA-PEGMA1100).