Endogenous hydrogen sulfide accelerated trauma-induced heterotopic ossification through the Ca 2+ /ERK pathway-enhanced aberrant osteogenic activity.

Unveiling of the mechanism involved in the occurrence and development of trauma-induced heterotopic ossification (tHO) is highly demanding due to current ineffective clinical treatment for it. Previous studies proposed that hydrogen sulfide (H ₂ S) was vital for fate determination of stem cells, suggesting a potential role in the regulation of tHO development. In the current study, We found that expression of metabolic enzyme within sulfur conversion pathway was enhanced after tendon injury, leading to H ₂ S accumulation within the tHO region. Increased production of endogenous H ₂ S was shown to promote aberrant osteogenic activity of tendon-derived stem cells (TDSCs), which accelerated tHO formation. The inhibition of metabolic enzyme of H ₂ S production or directly absorption of H ₂ S could abolished osteogenic induction of TDSCs and the formation of tHO. Mechanistically, through RNA sequencing combined with rescue experiments, we demonstrated that activation of Ca ²⁺ /ERK pathway was the downstream molecular event of H ₂ S-induced osteogenic commitment of TDSCs and tHO. For treatment strategy exploration, zine oxide nanoparticles (ZnO) as an effective H ₂ S elimination material was validated to ideally halt the tHO formation in this study. Furthermore, in terms of chirality of nanoparticles, D-ZnO or L-ZnO nanoparticles showed superiority over R-ZnO nanoparticles in both clearing of H ₂ S and inhibition of tHO. Our study not only revealed the mechanism of tHO through the endogenous gas signaling event from a new perspective, but also presented a applicable platform for elimination of the inordinate gas production, thus aiding the development of clinical treatment for tHO.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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