Local H<sub>2</sub> release remodels senescence microenvironment for improved repair of injured bone.

Chen, Shengqiang; Yu, Yuanman; Xie, Songqing; Liang, Danna; Shi, Wei; Chen, Sizhen; Li, Guanglin; Tang, Wei et al. · Nat Commun · 2023

basic_science · Level V

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Abstract

The senescence microenvironment, which causes persistent inflammation and loss of intrinsic regenerative abilities, is a main obstacle to effective tissue repair in elderly individuals. In this work, we find that local H<sub>2</sub> supply can remodel the senescence microenvironment by anti-inflammation and anti-senescence effects in various senescent cells from skeletally mature bone. We construct a H<sub>2</sub>-releasing scaffold which can release high-dosage H<sub>2</sub> (911 mL/g, up to 1 week) by electrospraying polyhydroxyalkanoate-encapsulated CaSi<sub>2</sub> nanoparticles onto mesoporous bioactive glass. We demonstrate efficient remodeling of the microenvironment and enhanced repair of critical-size bone defects in an aged mouse model. Mechanistically, we reveal that local H<sub>2</sub> release alters the microenvironment from pro-inflammation to anti-inflammation by senescent macrophages repolarization and secretome change. We also show that H<sub>2</sub> alleviates the progression of aging/injury-superposed senescence, facilitates the recruitment of endogenous cells and the preservation of their regeneration capability, thereby creating a pro-regenerative microenvironment able to support bone defect regeneration.

Medical subject headings