DOI: 10.25442/hku.28768463.v1
title: <i>Supporting data for “Multifunctional </i><i>microalgae</i><i>-based hydrogel promotes cell survival, suppresses anaerobic infection, and enhances vascularization</i><i>”</i>

description: Advanced tissue engineering strategies combining biomaterials, cells, and biomolecules hold immense potential forrepairing and regenerating damaged or lost tissues. However, critical challenges, such as insufficient oxygen and nutrient supply, waste metabolite accumulation, delayed vascularization, and infections, compromise transplanted cell survivaland function, ultimately hindering tissue regeneration. <i>Chlamydomonas reinhardtii</i> (<i>C. reinhardtii</i>), a unicellular green microalga, can photosynthetically convert carbon dioxide and water into oxygen and glucose and can be genetically engineered to produce recombinant proteins. Due to its ease of cultivation, rapid growth, excellent biocompatibility, high photosynthetic efficiency, and genetic manipulability, <i>C. reinhardtii</i><i> </i>is emerging as a valuable resource for biomedical applications. This study aimed to develop a microalgae-based hydrogel capable of producing photosynthetic oxygen and delivering pro-angiogenic growth factors to address hypoxia- and ischemia-related challenges in tissue engineering.This study was divided into three sections, each exploring a specific function of the microalgae-based hydrogel. First, <i>C. reinhardtii</i> demonstrated red autofluorescence, photosynthetic activity, and biocompatibility. In a two-dimensional (2D) coculture system with dental pulp stem cells (DPSCs) under hypoxic conditions, <i>C. reinhardtii</i> produced sufficient oxygen upon illumination to mitigate intracellular hypoxia without inducing oxidative stress, improving energy production, metabolic activity, and viability of DPSCs. To extend these findings, <i>C. reinhardtii</i> was immobilized in alginate microspheres and co-encapsulated with DPSCs within a gelatin methacryloyl (GelMA) hydrogel. This three-dimensional (3D) hydrogel generated sufficient oxygen to alleviate hypoxia, further enhancing DPSC metabolism and survival.The second section investigated the antimicrobial effects of photosynthetic oxygen generated by <i>C. reinhardtii</i> on anaerobic oral pathogens. The microalgae-based hydrogel enriched local oxygen levels, increasing reactive oxygen species (ROS) generation in <i>Porphyromonas gingivalis</i> (<i>P. gingivalis</i>) and <i>Fusobacterium nucleatum</i><i> </i>(<i>F. nucleatum</i>), thereby suppressing bacterial growth and viability. Additionally, the hydrogel exhibited inhibitory and destructive effects on multispecies biofilms, demonstrating its potential to prevent and eliminate anaerobic infections.In the third section, a transgenic <i>C. reinhardtii</i> strain (UVM4-VEGF) was introduced to simultaneously deliver bioactive vascular endothelial growth factor (VEGF) and oxygen. UVM4-VEGF were immobilized in alginate microspheres and co-encapsulated with DPSCs and human umbilical vein endothelial cells (HUVECs) within a GelMA hydrogel. This hydrogel sustained the release of VEGF and oxygen, improving vessel formation under hypoxic conditions and accelerating angiogenesis <i>in vivo</i>.In conclusion, this multifunctional microalgae-based hydrogel promotes transplanted cell survival, suppresses anaerobic infections, and enhances tissue vascularization by delivering photosynthetic oxygen and VEGF. This innovative approach addresses key challenges associated with ischemia and hypoxia in tissue engineering, offering a promising pathway for the clinical translation of engineered tissue constructs for tissue repair and regeneration.