Hydrogen sulfide-releasing silk fibroin scaffold for bone tissue engineering

Hydrogen sulfide (H₂S)-based therapy is a promising therapeutic strategy for several biomedical applications. Following the observation that endogenous and exogenous H₂S plays a prominent role as a bone anabolic agent, we recently developed a silk fibroin (SF) porous scaffold loaded with GYY4137 (GYY), an H₂S donor, for applications in bone tissue engineering. Here, we assayed whether the combination of SF with H₂S potentiates the osteoconductive properties of SF. Biocompatibility and osteoanabolic activity were assayed in vitro using human bone marrow mesenchymal stromal cells. Cell cultures were performed on a perfusion bioreactor to obtain results closer to the in vivo microenvironment. Cytotoxicity was excluded by lactate dehydrogenase and live/dead assays. Cell colonization and mineral apposition were evaluated by Haematoxylin & Eosin and Von Kossa/Alizarin Red-S stainings respectively. PCR array for human osteogenesis and immunohistochemical analyses were performed to identify pathways and targets involved. Our findings show that H₂S-releasing SF scaffolds supported cell adhesion, proliferation and viability. Moreover, H₂S activated genes and proteins involved in ossification, osteoblast differentiation, bone mineral metabolism and angiogenesis allowing a high and early mineralization. Based on these properties, we suggest the use of H₂S-releasing SF scaffolds for bone healing and regeneration applications.