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International Journal of Bioprinting Permeability of NiTi gyroid scaffolds

Figure 2. Schematic workflow for fluid flow simulation. Abbreviation: FV Mesh, finite volume mesh.
results for permeability were in the middle of the scatter On the second, fourth, and seventh day, the morphology
reported by participants and in good agreement with the of cultured cells in the presence of the test material was
analytical predictions. assessed with optical microscopy using AXIO Observer
A1 (Carl Zeiss, Germany). The number of cells at
2.5. Cell culture experiment different culture days was determined with an automated
For the biocompatibility assessment, gyroid samples were cell counter Countess II FL (Thermo Fisher Scientific,
consolidated in the form of a disk with a diameter of 10 mm USA). On the seventh day, MSCs’ number, viability, and
and a height of 1 unit cell. All as-built NiTi structures were proliferative index (culture doubling rate) were assessed.
subjected to ultrasonic cleaning in isopropanol to remove Afterward, the MSCs were fixed with formaldehyde 3.8%.
residual powder from pores. Before the cell seeding, The morphology of cells was analyzed with SEM Quattro S
scaffolds were washed twice with a sterile phosphate- (Thermo Fisher Scientific, the Netherlands).
buffered saline (PBS) solution and then autoclaved at
120°C for 40 min. In the first step, mesenchymal stromal 3. Results and discussion
cells (MSCs) provided by the Medical Center of Cellular
Technologies Dynasty (Samara, Russia) (License number: The gyroid surface can be implicitly represented by the
ЛО-63-01-005395) were unfrozen and washed with PBS following nodal equation:
to completely remove the cryoprotectant; afterward, cells 2 2 2 2
were counted to obtain their viability. A total of 0.4 × 10 cos a x sin a y sin a y cos a z
6

cells were transferred to the surface of a metal structure
using a variable volume dispenser; then culture medium sin 2 2 h (VII)
x
z cos

was added. Cultivation was carried out using standard a a
nutrient media, which included the following components: where a is the unit cell size, while constant h determines
liquid α-MEM nutrient medium with L-glutamine (Biolot the wall thickness and, accordingly, the relative density
LLC, Russia), 2 mM L-glutamine (Biolot LLC, Russia), of the whole structure. When h = 0, the gyroid represents
PRP (Platelet Rich Plasma of Cord blood, GBUZ “MC a minimal surface with zero thickness that divides the
Dynasty,” Russia). Also, Dulbecco’s phosphate-buffered volume by 50% each; when parameter h gradually increases
saline solution (DPBS, Biolot, Russia) and trypsin-EDTA from 0 to 1.413, a monotonic increase/decrease of both
solution (PanEco, Russia) were used for washing and volumes is observed. However, for engineering problems,
detaching cells, respectively. A 100 cm Petri dish seeded operating with the h parameter is not convenient. In studies
2
with the same number of MSCs was used as a control. dedicated to the biomedical applications of NiTi gyroid

Volume 10 Issue 1 (2024) 262 https://doi.org/10.36922/ijb.0119