Gravity-Tolerant In-Flight 3D Bioprinting Enabled by Stereolithography for Space Tissue Engineering.

Growing efforts toward long-duration human space missions demand novel strategies for the treatment of acute injuries in extreme environments. Technologies for space applications must perform reliably even under environmental stressors rarely encountered on Earth, such as gravitational fluctuations. However, space-compatible personalized therapy approaches for treatment of high-risk injuries remain scarce. 3D bioprinting represents an advanced technology with promising potential to address this unmet medical need by enabling the on-demand fabrication of patient-specific tissue constructs for regenerative wound care. Here, the robust 3D printing of both acellular and cell-laden hydrogel constructs is demonstrated using photo- and bioinks under diverse environmental conditions, including microgravity and hypergravity phases encountered during parabolic flight (0-1.8 g). Despite dynamic accelerative conditions, the developed flight-compliant, closed stereolithographic (SLA) bioprinting system successfully printed 3D structures with maintained dimensional fidelity. Irrespective of gravitational forces, high cell viability was preserved in both fibroblast- and keratinocyte-laden constructs. High-resolution features are achieved with precision comparable to normal-gravity controls. Complex architectures, including gyroids, can be fabricated with smooth, continuous surfaces. These findings establish SLA bioprinting as a robust and gravity-tolerant platform for fabricating viable, cell-laden constructs-offering a promising pathway for advancing tissue engineering in space and in extreme conditions on Earth.