Viability of Bioprinted Cellular Constructs Using a Three Dispenser Cartesian Printer

The overall goal of this procedure is to generate viable cell laden constructs with a complex geometry using a 3D Bioprint. This is accomplished by first isolating human adipose tissue stromal cells from culture. Next, the cells are mixed with freshly prepared oxidized RGD conjugated alginate bio ink.

In the final step, the cell LA in biomaterial is extruded via bioprinting. Ultimately, confocal microscopy is used to analyze the viability, proliferation, and migration of the bioprinted cells. The main advantage of this procedure over existing procedures, such as scaffold forming and cell seeding, is that with our procedure, you can directly place the cells and cell aggregates exactly where they need to be to form the tissue.

Demonstrating the procedure Today will be Sarah Grace Dennis, a graduate student from my laboratory. Begin by seeding 350, 000 human adipose tissue stromal cells onto a treated T 75 flask in 15 milliliters of low glucose TMEM for expansion in a cell culture incubator. When the culture reaches 80%co fluency, remove the medium and rinse the cells in five milliliters of DPBS without calcium and magnesium.

Then incubate the cells in five milliliters of trypsin and DPBS for two minutes at 37 degrees Celsius when the cells have detached, stop the enzymatic reaction with three milliliters of cell culture medium and transfer the cells into a 50 milliliter conical tube. Next, centrifuge the cells and resuspend the pellet in two milliliters of cell culture medium. Then count the cells, transfer a 1.3 times 10 of the six cell aliquot into a 15 milliliter conical tube and spin down the cells again.

Suspend the pellet in one milliliter of freshly prepared bio ink, taking care to homogenously, distribute the cells throughout the aqueous alginate solution. Then load the cells into a sterile printer compatible three milliliter syringe and screw on a sterile 22 gauge plastic tip. Now turn on the bioprint, each of the dispenser computers and the recirculating water bath.

Manually set the bath temperature to four degrees Celsius for the ation mechanism and the printing parameters for each dispenser on the correlating dispenser computer. Set the dispense volume to 230 nanoliters the number of back steps to zero, and the dispensary rate to 10 microliters per second. Then open the design software and the program for viewing the USB camera display on the computer.

Next, manually enter the coordinates for a five by five dot array with 2.4 millimeters of space between the drops. Save the program and send the program to the robot. Then place a gelatin titanium dioxide containing Petri dish on the four degree Celsius printer stage and close and lock the chamber door.

Using the programmable logic controller, initialized the ultraviolet light sources to sterilize the chamber. After 90 seconds, open the chamber and load the syringe containing the human adipose tissue stromal cell suspension into gun one close and lock the chamber door and use the programmable logic controller to turn on the fan system. Wait 30 seconds for the internal pressure to equilibrate and then run the program containing the geometrical pathway and printing parameters throughout the printing process.

Watch the USB camera display on the computer to confirm an accurate and uniform printing. To quantify the viability of the bioprinted constructs, immerse them in freshly prepared stain solution. Then place the constructs in the fridge for 15 minutes in the dark to allow the stain to set.

Then using a confocal microscope image, the stained constructs if the cells appear yellow or green, classify them as alive if red, the cells are dead. As these results demonstrate, bioprinting facilitates the deposition of cell aid and hydrogels in specific three dimensional locations accurately and consistently using computerated software. The computer software determines the placement of each droplet and controls many of the parameters for dispensing.

One of the requirements of a successful bioprinting technique is that the cells remain viable Here. Cells printed in alginic bio ink as just demonstrated, were analyzed one hour and eight days post printing with 98%of the cells appearing green and viable on day zero and to 95%on day eight. As the red staining indicates, few dead cells were observed at either time point confirming the suitability of the alternate ink for bioprinting.

Further, RGD conjugated algin ink enhances the attachment of the cells to the printed constructs leading to an improved cell spreading and proliferation as quantified in three separate areas of the hydrogel on a zero and eight. Here, a comparison of the quality of the RGD peptide conjugation on ginnet bio ink was compared to the use of Ginnet bio ink alone on day eight. The cell spreading observed in the RGD conjugated ginnet stained sample indicated the successful incorporation of the peptide on the ginnet, a phenomenon that was noticeably absent in the non conjugated bioprint samples After its development.

This technique paved the way for researchers in the field of tissue engineering to explore additive manufacturing as a means of assembling living engineered constructs.