PO-052 Study on the Expression of Inflammatory Factor, chemotactic factor in the Repair of Skeletal Muscle Contusion in Mic

Objective To investigate the regulation of muscle inflammatory factors and chemotactic factors during the repair of skeletal muscle contusion in mice. Methods Forty C57 male mice were needed. Eight for control group (C, n=8) and thirty-tow for muscle contusion group (S, n=32). Subsequently, their gastrocnemius muscles were harvested at 0d, 1d, 3d, 7d, 14d after injury. Hematoxylinand eosin (HE) stain were used to assess the changes of muscle morphology. In addition, the gene expression of inflammatory factors and chemotactic factors was analyzed by real-time polymerase chain reaction. Results 1、Morphology of skeletal muscles showed signs of regeneration at 3d post injury. The maximumamount of regeneration muscle fibers appeared during one week post contusion. Two weeks post-injury morphology of myofibers nearly recovered to normal. 2、After skeletal muscle injury, macrophage markers (CD68, CD163, CD206), a variety of inflammatory factors (IL-1, IL-6, IL-10) were up-regulated. 3、chemotactic factors (CCL2, CCL3, CCL5, CCL8, CXCL9, CXCL10, CXCL12, mRNA) were up-regulated。 Conclusions After skeletal muscle contusion, the expression of a variety of chemotactic factors is up-regulated, which promotes macrophage infiltration and produces a variety of inflammatory factors. They may be involved in the inflammatory response and regeneration process after skeletal muscle contusion.

OR-009 The expression and roles of lncRNAs in the regeneration of skeletal muscle contusion

Objective In recent years, Accumulating evidence from myoblast differentiation in vitro, cardiotoxin (CTX)-mediated injury or mdx mice suggested that some lncRNAs such as Malat1, H19, linc-MD1, linc-YY1, Sirt1 AS and lnc-mg may modulate myogenesis and muscle regeneration. However, the change of lncRNAs in skeletal muscle contusion and their possible roles are still unclear. We hypothesize that the lncRNAs may be involved in the repair of skeletal muscle contusion. Methods Forty C57BL/6 male mice were randomly divided into two groups, uninjured control group (group C) and muscle contusion group (group S). The mice of group S suffered from contusion injury. All the mice were killed to harvest gastrocnemius at 3, 6, 12 and 24 days post-injury. The gene expression were detected by PCR technique. Gastrocnemius were stained with H & E to evaluate the general morphology. Data were analyzed by One-way analysis of variance, with statistical significance being set at p ≤ 0.05. Results The expression levels of linc-MD1 and Sirt1 AS were significantly higher than that of the uninjured control group at 3, 6 and 12 days post-injury (p<0.01). And Malat1 was highly expressed in the skeletal muscle of the muscle contusion group at 3 days post-injury and continuously up-regulated at 6 days (p<0.01). Moreover, linc-YY1 and H19 were all elevated significantly at 6 days (all p<0.01), but their gene expression levels did not change significantly at 3, 12 and 24 days post-injury, as compared to the uninjured control group. Furthermore, lnc-mg mRNA level did not change significantly in the whole process of regeneration after muscle contusion except the time point of 12 days post-injury which decreased significantly (p<0.01). The expression of myogenic regulatory factors (MyoD, myogenin, myf5, myf6) were studied, they were all elevated significantly at 3 and 6 days (all p<0.01; except myogenin ), and returned to normal at 24 days post-injury, as compared to the uninjured control group. Meanwhile, Pearson correlations showed that there was an correlation between lincRNAs and myogenic regulatory factors mentioned above. Conclusions The expression of myogenic regulatory factors increased significantly after muscle contusion. Meanwhile, varieties of lncRNAs (Malat1, H19, lnc-mg, linc-MD1, linc-YY1, Sirt1 AS) were also up-regulated. Moreover, there was correlation between lncRNAs and myogenic regulatory factors for skeletal muscle regeneration. These results suggest that lncRNAs may play important roles in the regeneration of skeletal muscle contusion.

PL-003 BMSCs transplantation aggravate inflammation, oxidative stress, fibrosis and impair skeletal muscle regeneration

Objective Skeletal muscle contusion is one of the most common muscle injury in sports medicine and traumatology. Bone marrow mesenchymal stem cells (BMSCs) transplantation is a promising strategy for muscle regeneration. However, the roles of BMSCs, especially the mechanisms involved, in the regeneration of contused skeletal muscle are still not fully recognized. The aim of the study is to evaluate the potential of BMSCs transplantation for muscle regeneration and mechanisms involved after contusion. Methods Ninety-nine C57BL/6J mice were divided into three groups: control group (n=11), muscle contusion and BMSCs treated group (n=44), muscle contusion and sham treated group (n=44). BMSCs were immediately transplanted into gastrocnemius muscles (GMs) following direct contusion. At different time points (3, 6, 12 and 24 days) post-injury, the animals were killed and then GMs were harvested. Morphological and gene expression analyses were used to elevate the effect of BMSCs transplantation and mechanisms involved. Results The results indicate that BMSCs transplantation impairs muscle regeneration, as well as more fibrotic scar formation after skeletal muscle contusion. Furthermore, macrophages, inflammatory cytokines, chemokines, matrix metalloproteinases and oxidative stress related enzymes were significantly increased after BMSCs transplantation. These results suggest that BMSCs transplantation impairs skeletal muscle regeneration and that macrophages, inflammatory cytokines, chemokines, matrix metalloproteinases and oxidative stress related enzymes may be involved in the process. Conclusions BMSCs transplantation aggravates inflammation, oxidative stress and fibrosis, and impairs skeletal muscle regeneration, which shed new light on the role of BMSCs in regenerative medicine and cautions the application of BMSCs for muscle injury.