Abstract: BACKGROUND: Lijin manipulation can reduce fibrosis scar hyperplasia and promote skeletal muscle repair. However, improper activation of the Wnt/β-catenin signaling pathway can aggravate the fibrosis of injured skeletal muscle and adversely affect the repair process of skeletal muscle. To study the regulatory effect of Lijin manipulation on the Wnt/β-catenin signaling pathway is conducive to elucidate the related mechanisms of Lijin manipulation in reducing fibrosis scar hyperplasia and promoting skeletal muscle injury repair.
OBJECTIVE: To explore the mechanism of Lijin manipulation in promoting the repair of skeletal muscle injury in rabbits.
METHODS: Forty-five healthy adult Japanese white rabbits were randomly divided into blank group, model group and Lijin group with 15 rabbits in each group. Gastrocnemius muscle percussion modeling was performed in both model group and Lijin group. Lijin manipulation was performed in the Lijin group on the 3rd day after modeling, once a day, 15 minutes once. Five animals in each group were selected and killed on the 7th, 14th and 21st days after modeling. The general morphological structure of gastrocnemius was observed by hematoxylin-eosin staining and the content of collagen fiber was observed by Masson staining. Western blot was used to detect the protein expression of Wnt3a, β-catenin, GSK3β, p-GSK3β, TCF, type I collagen and type III collagen in gastrocnemius muscle, and RT-PCR was used to detect the mRNA expression of Wnt3a, β-catenin and TCF. The expression of β-catenin was detected by immunofluorescence, and the expression of type I collagen and type III collagen was detected by immunohistochemistry.
RESULTS AND CONCLUSION: The results of hematoxylin-eosin staining and Masson staining showed that compared with the model group, inflammatory cell infiltration and collagen fiber amount decreased in the Lijin group (P < 0.001), and muscle fibers gradually healed. Western blot results showed that compared with the model group, the protein expression levels of Wnt3a, β-catenin, TCF, type I collagen and type III collagen were significantly decreased in the Lijin group at all observation time points (P < 0.05), while the ratio of P-GSK3β/GSK3β was significantly increased in the Lijin group at all observation time points compared with the model group (P < 0.05). RT-PCR results showed that compared with the model group, the mRNA expression levels of Wnt3a, β-catenin and TCF were significantly decreased in the Lijin group at all observation time points (P < 0.001). Immunofluorescence results showed that compared with the model group, the fluorescence intensity of β-catenin expression in the Lijin group was significantly decreased at each observation time point and gradually became similar to that in the blank group (P < 0.001). Immunohistochemical results showed that the expression levels of type I collagen and type III collagen in the Lijin group were significantly lower than those in the model group (P < 0.01). To conclude, Lijin manipulation could inhibit the abnormal activation of the Wnt/β-catenin signaling pathway, reduce fibrotic scar hyperplasia, and promote the repair of injured skeletal muscle.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: Lijin manipulation, injury of muscle and tendon, musculoskeletal injuries, gastrocnemius muscle, fibrosis, scar, repair, Wnt/β-catenin signaling pathway