Abstract
Abstract: :
Purpose:Bone Morphogenetic Protein (BMP) is a bone growth factor, member of the TGF-ß superfamily which bone-inducing activity has been widely used in the treatment of injuries with bone loss. The purpose of this study was to evaluate the local host response of a bone matrix associated BMP in a guinea pig subcutaneous implant model. Methods:A bone matrix delivery system for BMP (BM-BMP) (Homus Biotechnology - São Paulo - Brazil) was implanted in the subcutaneous tissue of 20 guinea pigs (4 animals/group). The animals were sacrificed at 07, 15, 30, 60 and 180 postoperative days (PO) and the BM-BMP and the surrounding soft tissue were assessed for histopathological evaluation. The inflammatory response was quantified using an image analysis system to determine the thickness of the inflammatory cell infiltrate (ICI) and the fibrous capsule formation (FCF) surrounding the implant and the numbers of neovascularization per area of BM-BMP and adjacent tissue. The data were submitted to statistical analysis. Results:Light microscopy showed minimal ICI which increased until the 15 PO when a FCF surrounding the implant was observed. Although the inflammatory response decreased (P<0,05) after the 30 PO, inflammatory cells infiltration towards the implant were still observed. The 60 PO evaluation showed a significant decrease in the thickness of the FCF (P<0,05). The number of vessels revealed a tendency to decrease progressively until the 60 PO (P<0,05). Variation of the BM-BMP total area was not observed, although continuous absorption of the implant occurred. Conclusion:The BM-BMP implant elicited a minimal host response and absorption of the bone matrix was observed without, however, changing the implant total area.
Keywords: 506 pathology: experimental • 316 animal model • 429 image processing