The use of porous calcium phosphate scaffolds with transforming growth factor beta 1 as an onlay bone graft substitute

Abstract

Autogeneous bone grafting is regarded to be the golden standard for onlay grafts, but it requires a harvesting procedure and the remodeling pattern over time is unpredictable. New materials are constantly being sought to overcome these problems. An in vivo experiment was carried out to evaluate whether (1) porous calcium phosphate cement is a suitable biomaterial for onlay bone grafting, and (2) the addition of transforming growth factor beta 1 (TGF-beta1) accelerates de novo bone formation inside the cement porosity. A carrier of porous calcium phosphate cement (Calcibon) was designed and 16 rats received one preshaped implant each. In 8 out of 16 implants 0.75 mug TGF-beta1 was applied. The animals were killed after 4 weeks and the characteristics of tissue ingrowth into the onlay graft were evaluated. Histologic and quantitative histomorphometrical measurements demonstrated osteoid-like tissue formation in both experimental groups. The addition of TGF-beta1 did not induce significantly more osteoid-like tissue formation. On the other hand, in TGF-beta-loaded implants, a higher number of pores contained an inflammatory infiltrate. This study indicated that porous calcium phosphate cement is a promising material for clinical situations where bone formation has to be supported.