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

Figure 4

IGFBP-6 expression is altered by IGF-1 and IGF-2 treatment in PMSCs cultured under skeletal muscle differentiation conditions. (a) IGFBP-6 levels were increased by IGF-1 treatment at days 1 and 3 compared to PMSCs under muscle differentiation alone; however, they were reduced at days 7 and 14. IGF-2 treatment did not change IGFBP-6 levels until day 14 when they were increased compared to controls. IGFBP-6 levels were quantified by densitometry and normalized to β-actin. (b) IGFBP-6 secretion into conditioned media was increased with both IGF-1 (days 1 and 3) and IGF-2 (days 1 to 7) compared to controls. However, secreted IGFBP-6 levels were significantly decreased at 7 and 14 days with IGF-1 treatment, and remained increased with IGF-2 treatment. 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 control (PMSCs under muscle differentiation), or ^# and ^### comparing between IGF-1 and IGF-2 treatments.

(a)

(b)