Locally applied platelet-derived growth factor accelerates fracture healing.

Platelet-derived growth factor (PDGF) is known to stimulate osteoblast or osteoprogenitor cell activity. We investigated the effect of locally applied PDGF from poly-D,L-lactide (PDLLA)-coated implants on fracture healing in a rat model. A closed fracture of the right tibia of four-month-old Sprague-Dawley rats (n = 40) was stabilised with implants coated with a biodegradable PDLLA versus implants coated with PDLLA and PDGF. Radiographs were taken throughout the study, and a marker of DNA activity, bromodeoxyuridine (BrdU), was injected before the rats were killed at three, seven and ten days. The radiographs showed consolidation of the callus in the PDGF-treated group compared with the control group at all three time points. In the PDGF-treated group, immunohistochemical staining of BrdU showed that the distribution of proliferating cells in all cellular events was higher after ten days compared with that at three and seven days. These results indicate that local application of PDGF from biodegradable PDLLA-coated implants significantly accelerates fracture healing in experimental animals. Further development may help fracture healing in the clinical situation.