The effect of basic fibroblast growth factor on bone regeneration when released from a novel in situ setting tricalcium phosphate cement.

The osteostimulative effect of the basic fibroblast growth factor is well known, but it is dose dependent, and release kinetic depends on interactions with the used carrier. The aim of our study was to determine the osteostimulative effect of a composite, consisting of an in situ setting tricalcium phosphate cement and basic fibroblast growth factor. A trepanation defect of 1.5 mm in the femur diaphysis of Sprague-Dawley rats was filled with the in situ setting TCP cement combined with 0, 0.25, 2.5, or 25 microg rh bFGF, an autologous bone graft or left empty. The rats were euthanized after 1 and 3 weeks and examined by radiography, histology, histomorphometry, and bending test. The data were analyzed by the Wilcoxon and Kruskal-Wallis test. All TCP groups with or without bFGF showed a good bony ingrowth with a close bone-cement contact. Osseous ingrowth was not influenced by the addition of the different doses of bFGF as shown by histomorphometry. Also, mechanical strength was not affected. In conclusion, the combination of this in situ setting cement with bFGF is not useful for clinical application. The reason of these negative results remains unclear: the osteostimulative effect of bFGF is well known, and the TCP-cement was used as a carrier for rhBMP-2 successfully. These negative results may be due to a too slow or too fast release of bFGF from the cement.