Insulin-like growth factor-I improves chondrogenesis of predifferentiated human umbilical cord mesenchymal stromal...

Human umbilical cord mesenchymal stromal cells (hUCMSCs) are an attractive cell source for tissue engineering with numerous advantages over other adult stem cell sources, such as great expansion ability in vitro and extensive availability. The objective of this 6-week study was to test the hypothesis that switching from chondrogenic transforming growth factor-beta3 (TGF-beta3) to anabolic insulin-like growth factor-I (IGF-I) at the 3-week time point would produce more cartilage-like matrix than TGF-beta3 alone. hUCMSCs were seeded into polyglycolic acid (PGA) scaffolds and then cultured in chondrogenic medium containing TGF-beta3 for 3 weeks. The TGF-beta3-treated hUCMSCs were then exposed for 3 more weeks to one of four different conditions: (1) continued in chondrogenic medium, (2) control medium (no TGF-beta3), (3) control medium with 10 ng/ml IGF-I, or (4) control medium with 100 ng/ml IGF-I. Compared to continuing with TGF-beta3, switching to IGF-I increased collagen production, and furthermore increased both collagen type II gene expression and immunostaining. In conclusion, the shift from TGF-beta3 to IGF-I at week 3 resulted in a significant increase of cartilage-like extracellular matrix, confirming our hypothesis.