Retention of HB-IGF-1 in bovine cartilage explants following enzymatic digestion of glycosaminoglycans. (A) HB-IGF-1 or IGF-1 was incubated with cartilage disks for two days (Day 0 to Day 2) followed by treatment with no enzyme, chondroitinase (C’ase), or heparitinase (H’ase) for an additional two days (Day 2 to Day 4). At Day 4, a subset of chondroitinase-treated disks was incubated with heparitinase (C’ase+H’ase) for two days while all remaining disks were kept in enzyme-free medium. (B) Western analysis of HB-IGF-1 or IGF-1 remaining in the cartilage tissue at Day 6. The blot shown is representative of four repeats. (C) ELISA of HB-IGF-1 released to the medium following 48-hour enzyme treatment of cartilage explants (Days 2–4 for No enzyme, C’ase, and H’ase conditions; Days 4–6 for C’ase + H’ase). mean ± SEM, * vs. No enzyme, n=4, p<0.001.