Navigating Hypoxia in Tissue Engineering: From Biological Mechanisms to Therapeutic Strategies.

A major challenge in tissue engineering is the fabrication of clinically relevant cell-laden constructs at clinically relevant scales. In large or high-cell-density scaffolds, nutrient and oxygen demands cannot be met by diffusion alone in the absence of functional vasculature, often leading to cell death and necrotic core formation. This review examines the role of hypoxia in tissue engineering, with a focus on its development and cellular responses to low oxygen tension. We discuss hypoxia-driven signalling pathways and their influence on cell behaviour, angiogenesis, and extracellular matrix remodelling. Strategies for understanding and modelling oxygen dynamics are reviewed, together with approaches to mitigate hypoxia, including vascularisation and oxygen-generating materials, and hypoxia-inducing materials. Emerging tools, such as artificial intelligence, are also considered for their potential to predict and optimize oxygenation in engineered tissues. We propose that a deeper understanding of these mechanisms will unlock new possibilities for creating anatomically relevant living constructs with improved cell survival and tissue-specific differentiation. STATEMENT OF SIGNIFICANCE: In this article, we review hypoxia as one of the fundamental barriers to engineering large living constructs for regenerative medicine. Previous works have primarily focused individual aspects of hypoxia. Here, we aim to provide comprehensive overview of hypoxia, encompassing its development and cellular responses, and its influence on tissue formation. We also discuss strategies for profiling and monitoring hypoxia, as well as current approaches to mitigate and overcome it. New strategies to understand oxygen dynamics, including computational modelling and artificial intelligence, are also discussed. This review integrates fundamental biology with engineering solutions, offering a framework for the design of tissue constructs with enhanced function and therapeutic potential.