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, while challenges remain, such as the shortage of organ donors and complications associated with existing treatments. 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 restricture. These patients may benefit from a tissue-engineered urethra fabricated using autologous cells and 3D bioprinting.A printer setup for tubular structures was developed for a 3D-Bioplotter and a gelatin-fibrinogen-based bioink was supplemented with GelMA to enhance mechanical properties for clinical applications while maintaining cell compatibility. Evaluation was performed through tensile testing, printability, suturability and cell viability analyses. An artificial urethral graft was successfully fabricated, demonstrating the operational capacity of our rod-based printer setup and the GelMA-fibrinogen hydrogel exhibited an increase in Young's modulus compared with the gelatin-fibrinogen hydrogel. The GelMA-fibrinogen hydrogel also exhibited good suturability and efficient cell recovery after 14 days of 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 of culture, compared with the acellular graft.This 3D bioprinted artificial urethra, containing human urothelial and smooth muscle cells, represents a significant step forward in developing new treatment options for urethral disorders.