Fig. 2.

Effect of recombinant human growth and differentiation factor-5 (rhGDF-5) on proteoglycan (PG) synthesis, (top), collagen synthesis (middle), and PG content (bottom) by bovine NP and AF cells in vitro (From: Chujo T et al (2006) Trans Orthop Res Soc 14, with permission. Spine: in print). Top: Cells were cultured in DMEM/F12+10% FBS in the presence or absence of 100 and 200 ng/ml of rhGDF-5 for 21 days and then PG synthesis was assessed. NP cells treated with rhGDF-5 showed a greater response than AF cells. A dose-dependent effect of rhGDF-5 was observed in NP cells only at day 21. Middle: The rate of collagen synthesis was also significantly higher in the rhGDF-5 groups (100 and 200 ng/ml) than in the control group at all time points in both cell types. Bottom: On days 7, 14, and 21, the PG content in alginate beads was measured. rhGDF-5, at both concentrations, stimulated PG accumulation in beads containing NP cells at all time points and in beads containing AF cells at the 14- and 21-day time points