Dose-dependent osteoinductive effects of bFGF in rabbits

Growth factors lead to the induction of tissue regeneration in bone healing when coated on biomaterials. Basic fibroblast growth factor (bFGF) combines osteoinduction and neoangiogenesis. This study evaluated bFGF-coated hydroxylapatite implants in two experimental groups with 10µg or 100µg (n=5 per group) compared with uncoated control implants in the rabbit patellar groove model. We observed an unexpected ineffectiveness compared to the control groups with no significant difference of bone growth after 35 days. However all samples from the 100µg experiment (control and coated implant) showed significantly stronger 19-25 day label than both 10µg groups (control and coated implant). Earlier bone labels are stronger in the 10µg group with equal observation of similarity between experiment and control site and may indicate a possible inhibitory effect of the higher dosing or osteoclast induction. This result indicates a possible systemic effect of the transient growth factor coating. Keywords: Bone repair, Growth factors, Fibroblast growth factor, Hydroxyapatite, drug delivery, press-fit