Different Effects of Insulin-Like Growth Factor-1 and Insulin-Like Growth Factor-2 on Myogenic Differentiation of Human Mesenchymal Stem Cells

Figure 8

Model of IGFs and IGFBP-6 functions during PMSCs myogenesis. During myogenesis, PMSCs lose pluripotency-associated markers (OCT4, SOX2, and Nanog) and gain muscle commitment marker (Pax3/7) that decreased as muscle differentiation markers increase (MyoG, MyoD, and MHC). Committed and differentiated muscle cells expressed IGF-1, IGF-2, and IGFBP-6. Extracellular IGF-1 increased IGFBP-6 protein levels before PMSC muscle commitment, resulting in a delayed PMSC muscle commitment and differentiation. However, IGF-2 extracellular increase resulted in an increase in IGFBP-6 after commitment to the muscle lineage, resulting in full muscle lineage differentiation. Increased IGF-2 and IGFBP-6 levels also had a positive effect on OCT4 levels, but SOX2 and Nanog levels were decreased.