Synergistic Prevascularization with Proangiogenic Silica Nanoparticles and VEGF-Mimetic Aptamer in Tailored GelMA Hydrogels

Angiogenesis is a crucial and challenging requirement for the regeneration and repair of damaged tissues, particularly for critical-sized ones. To address this challenge, in this study, we fabricated a cell-communicating gelatin methacryloyl (GelMA) hydrogel using core-shell silica nanoparticles conjugated with roxadustat (FG-4592) and a VEGF-mimetic aptamer (Apt02). This hydrogel promotes tube formation and prevascularization synergistically through both extracellular and intracellular pathways in human umbilical vein endothelial cells (HUVEC), with FG-4592 acting via the extracellular pathway and Apt02 via the intracellular pathway. Fluorophore carbon quantum dot was synthesized and used as a core for constructing core-shell amine-functionalized silica nanoparticles (CQD@MSN-NH₂). Using human serum albumin (HSA) as a protein linker, FG-4592 was conjugated on the surface of the nanoparticles to the finalized CQD@MSN@HSA@FG-4592 (CMHF) theranostic proangiogenic nanoparticle. Several techniques were used to characterize structural and cytotoxic properties of CMHF nanoparticles. On the other hand, Apt02 was incorporated into the GelMA hydrogel to induce angiogenesis extracellularly. Results showed that the CMHF nanoparticle and Apt02 are cyto-compatible in periodontal ligament fibroblasts (PDLF) and HUVEC. The HUVEC tube formation assay indicated that 1.0 μM Apt02, 20 μM FG-4592, and 35 μg/mL of CMHF individually induced angiogenesis in HUVEC when 10 ng/mL VEGF was used as a positive control. Western blot and quantitative polymerase chain reaction assays of four genes revealed Apt02 to have an extracellular mechanism of action while FG-4592 increases cellular concentration of the hypoxia-inducible factor-1α (Hif-1α) transcription factor intercellularly and recruits HUVEC to form tube-like vessels both in vitro and ex ovo. In summary, our study introduces an injectable hydrogel containing a blend of 5% GelMA, 1.0 μM Apt02, and 35 μg/mL CMHF nanoparticles, which effectively enhances angiogenesis by activating both extracellular (through VEGFR) and intracellular (by Hif-1α overexpression) pathways and is more effective when targeting only one pathway.