Oxygen-enhanced assembloid-based vascularized intestinal-on-a-chip for radioprotective drug evaluation.

BACKGROUND

The intestine plays essential roles in digestion, immunity, and metabolism, but is highly sensitive to ionizing radiation during cancer treatment or environmental exposure. Although three-dimensional intestinal models more accurately replicate tissue architecture than conventional monolayers, they are frequently limited by insufficient oxygen delivery, leading to hypoxia-associated functional impairment. Incorporating physiologically relevant oxygenation strategies remains a key challenge in advanced in vitro systems. This study aimed to establish a physiologically relevant in vitro intestinal model by improving oxygen mass transfer within three-dimensional tissue constructs, thereby enhancing structural organization and functional maturation, and subsequently applying the system to investigate radiation-related mechanisms and evaluate potential protective agents.

METHODS

Based on a microengineered 3D cell-assembly platform, intestinal epithelial cells, endothelial cells, and fibroblasts were spatially organized to form a structured intestinal tissue model. The composition of the cells was optimised to improve tissue uniformity and the function of the epithelial barrier. To alleviate hypoxia in the three-dimensional construct, an oxygen-permeable microwell system was employed to enhance oxygen diffusion and promote epithelial differentiation, as evidenced by the upregulation of Isx, Cyp3a5, and Tff3. A vascularized chip that recapitulated the in vivo intestinal-stromal-vascular interface was created by incorporating microvascular networks self-assembled from endothelial cells within a hydrogel matrix.

RESULTS

Following radiation exposure, the model exhibited characteristic symptoms of intestinal injury, such as decreased cell viability, impaired E-cadherin signaling, and compromised epithelial barrier integrity. Treatment with dimethyloxalylglycine (DMOG) mitigated these effects, confirming it's utility for assessing radioprotective drugs.

CONCLUSION

This vascularized intestinal-on-a-chip model closely mimics the structure and function of the human intestinal microenvironment. It serves as a robust in vitro platform for studying radiation-induced intestinal injury and for screening candidate protective agents, offering valuable applications in radiation protection and regenerative medicine research.