Se@SiO₂ Nanoparticles Improve Oxidative Injury To Promote Muscle Regeneration Via Modulating Mitochondria

Background and purpose:Skeletal muscle injuries are common in daily life and sports,and are an important cause of motor disability.However,current treatments for skeletal muscle injury are limited and cannot achieve satisfactory outcomes.Although satellite cells(SCs),as skeletal muscle stem cells,can participate in the repair of skeletal muscle after injury.However,more severe injuries often exceed the compensatory capacity of satellite cells,resulting in incomplete skeletal muscle regeneration and excessive fibrosis.Various studies have shown that mitochondrial functional and structural damage occurs early after skeletal muscle injury,and that mitochondria have irreplaceable biological functions in addition to energy supply for skeletal muscle.Thus,we developed a porous Se@SiO2 nanoparticles(NPs),which can reduce oxidative cellular damage due to their antioxidant properties,and may promote satellite cell proliferation and differentiation through mitochondria,thereby promoting skeletal muscle regeneration.Materials and methods:Porous Se@SiO2 NPs were synthesized strictly with reference to the standards used in our previous study.primary SCs were extracted and identified from neonatal male SD suckling mice,and heirloom cells were grown in an incubator and induced to myogenic differentiation of SCs.The in vitro oxidative stress microenvironment was simulated by H2O2,while the biocompatibility of Se@SiO2 NPs was examined by MTT assay,and its effect on the proliferation of SCs cells was determined,and the appropriate concentration was selected for subsequent experiments.Then the cells were divided into four groups:Control group,Se@SiO2 group,H2O2 group,and Se@SiO2+H2O2 group.Cell death and cell senescence were detected by live cell staining with senescence-associated βgalactosidase staining.ROS production in mitochondria and changes in mitochondrial density were detected by fluorescent probe labeling.Mitochondrial complex,ATP synthase and catalase activities were measured by respiratory chain activity assay kits.The effects on myogenic differentiation of SCs were examined by immunofluorescence as well as Westernblot.Meanwhile,we constructed a conventional model of skeletal muscle injury by tibialis anterior cardiotoxin(CTX)injection in rats,which were divided into four groups:Control group,CTX group,Se@SiO2 group,and Se@SiO2+CTX group by intraperitoneal as well as local Se@SiO2 NPs administration.The effects of Se@SiO2 NPs on skeletal muscle regeneration were evaluated at the histological level by HE staining as well as Masson staining and immunofluorescence staining,and the expression of key proteins in the process of myogenic differentiation was examined by Western-blot.Results:We successfully synthesized porous Se@SiO2 NPs,which have a particle diameter of approximately 55 nm,following standard procedures,and successfully extracted primary SCs,which were identified by their markers Desmin as well as Pax7.In in vitro experiments,we explored the optimal action concentration of porous Se@SiO2 NPs,whose appropriate concentration promoted the proliferation of SCs without significant cytotoxicity.We simulated the oxidative stress microenvironment by H2O2,which produced significant damage to cells.Porous Se@SiO2 NPs attenuated cell death as well as senescence and mitigated the cell damage caused by H2O2.Porous Se@SiO2 NPs significantly reduced mitochondrial reactive oxygen levels at the early and late stages of cell differentiation and maintained the morphological stability of mitochondria under H2O2 exposure.In addition,porous Se@SiO2 NPs protected the functional stability of mitochondria by promoting the activity of the mitochondrial respiratory chain complex and increasing the activity of endogenous antioxidant enzymes.This protects SCs from H2O2-induced damage to cell proliferation and myogenic differentiation.In in vivo experiments,skeletal muscle necrosis and inflammation could be observed significantly after CTX injection in the tibialis anterior muscle,and the skeletal muscle regenerated slowly overtime,indicating successful modeling.Subsequent Se@SiO2 NPs were administered by local as well as intraperitoneal routes,and the intervention of porous Se@SiO2 NPs promoted muscle regeneration and attenuated fibrotic deposition between regenerated skeletal muscles as observed by histological HE staining with Masson staining.As observed by immunofluorescence and Western blot,porous Se@SiO2 NPs significantly promoted the expression of MyHC,a key protein for muscle regeneration,as well as Myod.Conclusion:This study demonstrated that porous Se@SiO2 NPs could significantly promote the proliferation and myogenic differentiation of SCs under oxidative stress microenvironment by scavenging mitochondrial ROS and increasing mitochondrial activity.It also accelerated the regeneration of skeletal muscle after injury and reduced fibrotic deposition.