Enhancing the Structural Integrity of 3D Bioprinted Urethral Grafts for Clinical Applications using GelMA-Fibrinogen Bioinks Infused with Human Primary Cells.

The demand for organ transplantation continues to grow, since the shortage of organ donors and complications associated with existing treatments remain. A promising alternative to transplantation is the implantation of artificial organs, which can be produced using 3D bioprinting technology. This approach offers the advantage of patient-specific solutions tailored to individual needs. Patients with urethral stricture or hypospadias who are unable to urinate require urethral reconstruction, which carries risks of complications and stricture recurrence. These patients may benefit from a tissue-engineered urethra fabricated using autologous cells and 3D bioprinting. Therefore, a printer setup for tubular structures was developed for 3D-Bioplotter, and a gelatin-fibrinogen-based bioink was optimised by supplementation with GelMA to enhance mechanical properties suitable for clinical applications while maintaining cell compatibility. Tensile testing, printability, suturability, and cell viability analyses were performed to assess the outcomes of the different ink compositions. An artificial urethral graft was successfully printed, using our rod-based printer setup, and the GelMA-fibrinogen hydrogel exhibited an increase in Young's modulus compared with gelatin-fibrinogen hydrogel. Further, the 5% GelMA-fibrinogen hydrogel also exhibited good suturability and maintained cell viability after 14 days in culture. Human urothelial and smooth muscle cells developed characteristic morphologies within the print, and a 210% increase in burst pressure was observed for the urethral graft after 14 days in tissue culture, compared with the acellular graft. Our 3D bioprinted artificial urethra herein, containing an inner layer of human urothelial cells stabilised with polycaprolactone and an outer ring of smooth muscle cells, represents a significant step forward in replicating natural urethral architecture for developing grafts as new treatment options for urethral disorders.