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

Figure 5

IGF-2 knockdown with siRNA inhibited PMSC differentiation into skeletal muscle and adding extracellular IGFBP-6 with the treatment helped rescue muscle compaction. (a) Compared to PMSCs under muscle lineage differentiation conditions with siRNA scrambled control, (b) PMSCs under muscle differentiation conditions treated with IGF-2 siRNA showed less skeletal muscle compaction at 14 days (10x). (c) Extracellular IGFBP-6 supplementation with IGF-2 knockdown enhanced the PMSC muscle compaction at 14 days compared to IGF-2 siRNA. The white arrows indicate muscle compaction. (d) IGF-2 levels by PMSCs treated with IGF-2 siRNA under differentiation conditions were reduced and returned to control levels by day 14, while adding IGFBP-6 with IGF-2 knockdown maintained lower IGF-2 levels. (e) IGFBP-6 protein levels increased until day 3 with IGF-2 knockdown compared to siRNA scrambled control. IGFBP-6 addition with IGF-2 knockdown increased IGFBP-6 protein levels at each time point. Protein levels were quantified by densitometry and normalized to β-actin. Data is presented as the mean ± SEM of 3 independent experiments. Two-way ANOVA with Bonferroni’s multiple comparison test was performed to determine , , and compared to scrambled siRNA control, or ^# and ^### compared to IGF-2 siRNA.

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