Page 420 - IJB-9-2

International Journal of Bioprinting Design and 3D printing of TPMS breast scaffolds

named Raise 3D Pro2 (Raise 3D, Shanghai, China). twice with 2 mL PBS, and then the cells were digested with
The biodegradable PCL filaments (Yasin3D, Dongguan, 1 mL trypsin for 2 min. Once the cells were completely
China) were used to print TPMS scaffold. The nozzle separated from the culture flask, 2 mL medium was added
temperature, platform temperature, printing speed, and into culture flask to terminate the digestion, and the cells
layer thickness were set as 110°C, 65°C, 15 mm/s, and were counted with the cell counting plate. After that, the
0.2 mm, respectively. The porosities of the printed TPMS cell suspension was centrifuged at 1000 r/min for 5 min,
scaffolds were measured by drainage method. The channel and then the supernatant was discarded, and the cells
diameters of the scaffolds were measured under a digital were resuspended with the prepared hydrogel solution
microscope (Dino-Lite, Taiwan, China). to obtain the cell-loaded hydrogel with a cell density of
1 × 10 w cells/mL.
6
2.4.2. Compression tests of TPMS scaffold
2.4.4. Fabrication of TPMS scaffold loaded with
The mechanical properties of TPMS scaffolds were
evaluated through uniaxial single and cyclic compression hydrogel
tests on AGS-X (Shimadzu, Japan) with a 5KN load cell. The TPMS scaffold and mold were disinfected with
Briefly, the scaffold was placed on the fixed rigid bottom 75% alcohol, and then were sterilized and dried under
plate, and the movable rigid upper plate connected ultraviolet light for 24 h. The TPMS scaffold was placed
with the load cell compressed the scaffold with a speed in the mold. Subsequently, the hADSCs-loaded hydrogel
of 5 mm/min. The compression process continues until the was perfused into the mold, and then, the hydrogel was
scaffold strain reached 60%. The force-displacement curve cured under ultraviolet light for 30 s. The fabricated TPMS
can be obtained through the compression test and then the scaffold loaded with hydrogel was put into a well plate,
stress-strain curve of the scaffold can be further obtained. and the medium was added into the well plate to cover the
The slope of the linear stage of the stress-strain curve is the scaffold. Finally, the scaffold was cultured in an incubator
elastic modulus of the TPMS scaffold. To assess the fatigue (Heal Force, Shanghai, China) with temperature of 37°C
resistance of the scaffold, uniaxial cyclic compression tests and carbon dioxide concentration of 5%, and the medium
with a compression and rebound speed of 20 mm/min was changed every day.
were carried out. The compression process continues
until the scaffold strain reached 50%, and then the upper 2.4.5. Biocompatibility test of scaffold
plate began to rebound immediately until it returned to its To evaluate the biocompatibility of the TPMS scaffold
original position, and this process repeated 10 times. loaded with hydrogel, the live/dead staining assay was
performed after 24 h of culture. In the control group, the
2.4.3. Fabrication of hADSCs-loaded hydrogel cells were directly encapsulated in the hydrogel. Specifically,
The hydrogel solution contains 4% w/v poly (ethylene the fluorescent dye was prepared with the volume ratio of
glycol) diacrylate (PEGDA; MW: 6000, Ponsure Biological, PBS: calcein AM: propidium iodide (PI) = 1000:1:1. The
Shanghai, China), 6% w/v gelatin methacrylate (GelMA; medium in the well plate was discarded and the samples
Black Flame Medical, Shanghai, China), and 0.5% w/v were washed twice with PBS, and then the fluorescent dye
lithium phenyl(2,4,6-trimethylbenzoyl) phosphinate (LAP; was added into the well to cover the samples. After that,
Yinchang New Materials, Shanghai, China). Specifically, the samples were put into incubator for 10 min. Finally,
GelMA, PEGDA, and LAP powders were weighed and the activity of hADSCs was observed under fluorescence
added into phosphate-buffered saline (PBS) in turn. microscope (Olympus, Japan).
After each powder was added, the solution was heated in
a 40°C water bath for 10 min, and then the solution was 2.5. Statistical analysis
stirred until the powder was completely dissolved before All experimental data of this study are expressed as
the next powder was added. Then, the pH of the hydrogel mean ± standard deviation or presented in original data.
solution was adjusted to 7.4 using sodium hydroxide and In the mechanical property tests, the number of samples
hydrochloric acid standard titration solution. After that, in each group was n = 3, and in the biocompatibility
the hydrogel solution was drawn into a syringe and then experiment, the number of samples in each group was
injected into a filter for filtration. The hADSCs (QCHENG n = 5. One-way analysis of variance (ANOVA) was used
BIO, Shanghai, China) were cultured in the complete to determine the significant difference between multiple
medium (basic culture medium: fetal bovine serum: groups of data, and P < 0.05 indicates that there was a
penicillin: streptomycin: cell growth factor = 100:10:1:1:1). significant difference between the groups and P < 0.01
To prepare the cell-loaded hydrogel, the medium in the indicates that there was a very significant difference
culture flask was discarded, and then the cells were washed between the groups.

Volume 9 Issue 2 (2023) 412 https://doi.org/10.18063/ijb.685