Muscle-derived Exosomes Regulate The Proliferation And Differentiation Of SCs And Faps To Promote Skeletal Muscle Regeneration

Skeletal muscle is the largest organ in an animal organism.It is responsible for the metabolism,energy balance and movement of the whole organism,and serves as a body protein pool of the organism.However,any deterioration in skeletal muscle material metabolism and contraction characteristics will significantly affect the meat quality and aesthetics of animal products.However,any deterioration in skeletal muscle material metabolism and contraction characteristics will significantly affect the meat quality and aesthetics of animal products.Studies have shown that muscle-satellite cells(SCs)are the primary stem cells directly responsible for the formation of new fibers,which are activated to proliferate to promote muscle growth and remodeling,or to repair damaged muscles after muscle injury.In addition,Fibro/adipogenic progenitors(FAPs)also play a role in myogenesis.FAPs have inherent fat-producing and fibroblasting potential,meaning a potential threat to fibrosis and fat accumulation in diseased muscles.Exosomes are nanoscale vesicles secreted by living cells.They reach target cells through various transport routes to exert various physiological effects.They are a medium for cell communication.This study promotes skeletal muscle growth and development through targeted activation of SCs and inhibition of FAPs differentiation by muscle-derived exosomes.The result is as follows:(1)Identification of C2C12 cell-derived exosomes using Nanosight,transmission electron microscopy,and Western Blotting.Nanosight results show that the diameter distribution of the nanoparticles is in the range of 80-269 nm,the peak is 157 nm,the concentration is 4.1 × 109 particles / m L,and it conforms to the Brownian motion of irregular motion.Transmission electron microscopy was used to detect exosomes with a diameter of about 150 nm,which was a typical bilayer membrane spherical vesicle structure.Western Blotting detected the expression of exosome-specific markers CD9 and TSG101,all of which were positive.It shows that the method used in this study can efficiently extract C2C12-derived exosomes.(2)q RT-PCR and Western Blotting were used to detect the expression of markers of myogenesis,markers of muscle fibrosis and markers of muscle adipocyte at different times.The results showed that fibrosis reached the highest level after 5 days of muscle damage,and fibrosis was greatly reduced under the action of exosomes.After 3 days of muscle damage,muscle adipocyte increased due to the role of exosomes,proving that exosomes can Increased adipocyte of injured muscles;at 5 days,exosomes played a role in myogenesis to promote myogenesis.This study proves that myogenic exosomes can reduce fibrosis of injured muscles,promote fat production,and facilitate the regeneration of injured muscles.(3)SCs and FAPs were sorted by flow cytometry,and proliferative markers of SCs,FAPs became fibrogenic and adipogenic markers were detected by q RT-PCR,Western in cell.The results showed that exosomes promoted SCs proliferation,FAPs fibrogenic decreased,and adipogenic increased.In conclusion,the above results fully proves that muscle-derived exosomes can target SCs and FAPs in muscle cells to promote skeletal muscle regeneration.At the same time,this study provides a theoretical basis for muscle development mechanisms,diagnosis and treatment of related diseases,and for obtaining high-quality meat breeds in the animal husbandry industry.