To prepare the bio ink solution mix an appropriate amount of C3A cell suspension with the sterilized gelMA solution. Prestain the C3A cell spheroids with two micromolar cell tracker solution at 37 degrees for 20 minutes. To wash the cells, first, remove the supernatin by centrifuging and then add fresh cell culture medium.
Add at least two milliliters of bio ink into the sterilized acoustic device chamber. Turn on the function generator and power amplifier to initiate the actuation of each PZT transducer to generate a 3D array of cell aggregates. Crosslink the bio ink using blue light for 30 seconds to create 3D hydrogel scaffolds, encapsulating the assembled cell aggregates acoustically.
Next, carefully transfer the 3D hydrogel scaffold from the chamber into a Petri dish. Cut it into small pieces using a clean razor, and then add cell culture medium into the Petri dish. Incubate the C3A cell spheroids at different culture time points in one milliliter of PBS containing one microliter of calcium am and two microliters of propidium iodide for 15 minutes at 37 degrees Celsius.
Rinse the sample embedded in hydrogel scaffolds twice with PBS. For retrieved spheroids, perform centrifugation at 200 G for five minutes and wash twice with PBS. Using a fluorescence microscope, observe the spheroids and capture the images.
The cell aggregates were arranged in the regular 3D dot array pattern with a green fluorescent signal. The assembled C3A gelMA aggregates gradually integrated and formed tight spheroids by day three, accompanied by an increase in spheroid diameter. The viability of the cell spheroids remained good before day three, but slightly decreased after a week of culture.
The released spheroids maintained a good spherical morphology with a narrow size distribution along with desirable viability and expression of albumin.
