H2S/NO gasotransmitter-releasing nanofibers functionalized on implants accelerate osseointegration by coordinating osteogenic, angiogenic, and immunoregulatory responses

Dental implants face challenges such as poor osseointegration, delayed angiogenesis, and chronic inflammation. Endogenous gaseous signaling molecules hydrogen sulfide (H 2 S) and nitric oxide (NO) have emerged as key gasotransmitters that regulate angiogenesis, osteogenic differentiation and immune responses, making them attractive candidates for microenvironment-targeted therapies. Here, we engineer a dual gasotransmitter-releasing coating by co-electrospinning hydrogen sulfide (H 2 S) and nitric oxide (NO) donors, JK-2 and S-Nitroso- N -acetyl-DL-penicillamine (SNAP), into gelatin/polycaprolactone (Gel/PCL) nanofibers (NFs). These NFs were applied to laser-microgrooved titanium (Ti) surfaces, further modified with polyepigallocatechin gallate (pEGCG) to ensure stable attachment. The resulting coating exhibited sustained, pH-responsive release of H 2 S and NO, which acted synergistically to enhance cellular responses. In vitro , the dual gasotransmitter-releasing NFs coating enhanced endothelial cell migration, tube formation, and upregulated angiogenic markers (VEGF, TGF-β1, eNOS). Additionally, MC3T3 preosteoblasts showed increased alkaline phosphatase (ALP) activity, mineralization, and upregulation of osteogenic genes (Runx2, COL1, OPN, OPG). RNA-sequencing identified enriched pathways related to histone methylation and oxidative phosphorylation, crucial for osteogenesis and cellular metabolism. Macrophages cultured with these NFs demonstrated suppressed M1 pro-inflammatory markers and enhanced M2 polarization, indicating a shift toward a more regenerative immune response. In vivo , the NFs coating significantly improved neovascularization, bone volume, collagen deposition, and peri-implant tissue thickness. This synergistic release of H 2 S and NO provides a promising strategy to enhance osseointegration and bone regeneration by modulating angiogenesis and immune responses.