Comparison of HB-EGF with bFGF and contribution of FCS to proliferation enhancement. To assess the proliferating cell rate, 3H-thymidine incorporation assay was run for 72 hours (A) and 7 days (B), and the effect of HB-EGF was compared with that of 1 ng/mL basic fibroblast growth factor (bFGF), with or without FCS, a normal constituent of the complete culture medium that might contain growth factors. The enhancement of MSC proliferation rate by HB-EGF is dose dependent, with little difference between 25 and 50 ng/mL, and the effect with 50 ng/mL concentration is lower but not far from that achieved by adding 1 ng/mL bFGF to the culture. With both growth factors, as well as with normal medium, MSC proliferation depends on the presence of FCS, thus indicating that the increase of proliferation rate is actually due to the specific effect of those growth factors and not to FCS components. In the presence of FCS, the difference between the arm without HB-EGF and the others is statistically significant (P < .01). The figure shows means ± SD of 5 different experiments.
