3.2 Scaffold
Fabrication
Multiple 3D printing technologies are available for the scaffold
fabrication, each offering specific advantages and disadvantages.
For this method, stereolithography (SLA; Accura
® ClearVue™;
VIPER si2™ SLA
® , 3D Systems) was used, but the workflow can
be adapted to other systems, such as fused deposition modeling
(FDM) (see Note 12).
1. Open the 3D model in the printer software.
2. Define the printing orientation of the model in order to get the
best quality and to reduce the support material required for
overhanging geometry. In this procedure, the tubular structures were oriented longitudinally.
3. Based on the laser diameter and resin solution define the printing parameters, such as layer thickness, hatch spacing, fill
spacing, infill pattern, and density. To produce the tubular
scaffolds, the fenestrated mesh-like structures were printed
with Accura
® ClearVue™. The printed layers height was set
to 0.004
00 (ca. 100 μm) as the laser diameter used was 100 μm.
4. Once all of the required parameters have been defined, execute
the slicing of the model and export the G-code file containing
the printing instructions.
5. Load the file on the VIPER si2™ SLA
® 3D printer and initiate
the printing.
6. At the end of the process, clean the 3D-printed construct with
isopropyl alcohol to remove the excess resin, dry and postprocess with UV light (λ ¼ 365 nm, t ¼ 30 min).
7. In case the scaffolds are printed with support material, remove
it after UV-curing. Moreover, to smooth the lattice surface and
eliminate support marks, the printed object can be rinsed with
water and/or water mixed with sand.
3.3 Hydrogel
Preparation
1. If encapsulating MRC-5 lung fibroblasts in the hydrogel, prepare a concentrated cell suspension of MCR-5 lung fibroblasts
in the culture medium. The concentration of the suspension
will depend on the confluency and number of plates available.
2. Prepare a fresh batch of hydrogel precursor solution under
sterile conditions (Subheading 2.3). If encapsulating MRC-5
lung fibroblasts, add the appropriate volume of the concentrated cell suspension to achieve a final concentration of
MRC-5 lung fibroblasts of 1.0 Â 10
6 cells/mL. Triturate to
ensure homogeneity of the cells in the hydrogel precursor
solution.
3. Maintain the hydrogel precursor solution at 37
C during use.
The prepared solution should be used with ~2 h without cells
and as quickly as possible if cells are suspended in the precursor
solution.
Surface Tension-Assisted Additive Manufacturing
155
Fabrication
Multiple 3D printing technologies are available for the scaffold
fabrication, each offering specific advantages and disadvantages.
For this method, stereolithography (SLA; Accura
® ClearVue™;
VIPER si2™ SLA
® , 3D Systems) was used, but the workflow can
be adapted to other systems, such as fused deposition modeling
(FDM) (see Note 12).
1. Open the 3D model in the printer software.
2. Define the printing orientation of the model in order to get the
best quality and to reduce the support material required for
overhanging geometry. In this procedure, the tubular structures were oriented longitudinally.
3. Based on the laser diameter and resin solution define the printing parameters, such as layer thickness, hatch spacing, fill
spacing, infill pattern, and density. To produce the tubular
scaffolds, the fenestrated mesh-like structures were printed
with Accura
® ClearVue™. The printed layers height was set
to 0.004
00 (ca. 100 μm) as the laser diameter used was 100 μm.
4. Once all of the required parameters have been defined, execute
the slicing of the model and export the G-code file containing
the printing instructions.
5. Load the file on the VIPER si2™ SLA
® 3D printer and initiate
the printing.
6. At the end of the process, clean the 3D-printed construct with
isopropyl alcohol to remove the excess resin, dry and postprocess with UV light (λ ¼ 365 nm, t ¼ 30 min).
7. In case the scaffolds are printed with support material, remove
it after UV-curing. Moreover, to smooth the lattice surface and
eliminate support marks, the printed object can be rinsed with
water and/or water mixed with sand.
3.3 Hydrogel
Preparation
1. If encapsulating MRC-5 lung fibroblasts in the hydrogel, prepare a concentrated cell suspension of MCR-5 lung fibroblasts
in the culture medium. The concentration of the suspension
will depend on the confluency and number of plates available.
2. Prepare a fresh batch of hydrogel precursor solution under
sterile conditions (Subheading 2.3). If encapsulating MRC-5
lung fibroblasts, add the appropriate volume of the concentrated cell suspension to achieve a final concentration of
MRC-5 lung fibroblasts of 1.0 Â 10
6 cells/mL. Triturate to
ensure homogeneity of the cells in the hydrogel precursor
solution.
3. Maintain the hydrogel precursor solution at 37
C during use.
The prepared solution should be used with ~2 h without cells
and as quickly as possible if cells are suspended in the precursor
solution.
Surface Tension-Assisted Additive Manufacturing
155