Mesenchymal Stromal Cell Secreted Sphingosine 1-Phosphate (S1P) Exerts a Stimulatory Effect on Skeletal Myoblast Proliferation

Abstract

Bone-marrow-derived mesenchymal stromal cells (MSCs) have the potential to significantly contribute to skeletal muscle healing through the secretion of paracrine factors that support proliferation and enhance participation of the endogenous muscle stem cells in the process of repair/regeneration. However, MSC-derived trophic molecules have been poorly characterized. The aim of this study was to investigate paracrine signaling effects of MSCs on skeletal myoblasts. It was found, using a biochemical and morphological approach that sphingosine 1-phosphate (S1P), a natural bioactive lipid exerting a broad range of muscle cell responses, is secreted by MSCs and represents an important factor by which these cells exert their stimulatory effects on C2C12 myoblast and satellite cell proliferation. Indeed, exposure to conditioned medium obtained from MSCs cultured in the presence of the selective sphingosine kinase inhibitor (iSK), blocked increased cell proliferation caused by the conditioned medium from untreated MSCs, and the addition of exogenous S1P in the conditioned medium from MSCs pre-treated with iSK further increased myoblast proliferation. Finally, we also demonstrated that the myoblast response to MSC-secreted vascular endothelial growth factor (VEGF) involves the release of S1P from C2C12 cells. Our data may have important implications in the optimization of cell-based strategies to promote skeletal muscle regeneration.

Platelet releasate promotes skeletal myogenesis by increasing muscle stem cell commitment to differentiation and accelerates muscle regeneration following acute injury

“…This may possibly be due to a crosstalk with other growth factor receptors present in the releasate such as EGFR when used in high concentrations . This notion is strengthened by previous studies showing that PDGF/VEGF inhibition resulted in diminished myoblast proliferation and recombinant PDGFs improved skeletal muscle recovery after injury …”

“…Given the above observations that mRNA and protein levels of PDGF and VEGF are increased in proliferating myoblasts (Figure ), as well as their abundance in the releasate (Figure ), we reasoned that these growth factors may be governing cell proliferation, as shown when individually targeted . To further investigate this notion, we used low, medium and high doses of VEGFR or PDGFR Inhibitors with or without releasate to assess C2C12 cell proliferation (Figure A,B).…”

Platelet biology in regenerative medicine of skeletal muscle

“…A schematic diagram showing a skeletal muscle stem cell's (ie, satellite cell) possible response to growth factors, based on current published evidence . Located between the basal lamina and the sarcolemma of the muscle fibre, the satellite cell may come into contact with hundreds of growth factors and cytokines in response to platelet‐rich plasma ( PRP ) administration.…”

“…Some of the cell types in Table include myogenic progenitor cells, bone‐derived periosteal cells, osteosarcoma, endothelial, trabecular bone cells, human adipose‐derived mesenchymal stem cells, fibroblasts, tenocytes, myo‐endothelial cells, pericytes, C2C12 cells, adipose‐derived stem cells and muscle satellite cells. Variable levels of differentiation have been reported for different cell types, for example increased differentiation for rat bone marrow cells, human skeletal muscle myoblasts, rat muscle satellite cells, rabbit bone marrow mesenchymal stem cells and C2C12 myoblasts or maintained effect with hMDPCs, myo‐endothelial cells and pericytes compared to control conditions . Conversely, some studies reported that platelets inhibited differentiation of C2C12 myoblasts .…”

Effect of Bone Marrow Mesenchymal Stem Cells on Satellite Cell Proliferation and Apoptosis in Immobilization-Induced Muscle Atrophy in Rats

“…In our study, we found no resident cells with GFP. Indeed, studies indicate that MSCs stimulate skeletal myoblast proliferation and differentiation via the release of paracrine factors such as S1P (sphingosine 1-phosphate) [26] or VEGF (vascular endothelial growth factor) [27]. …”