EARLY OSTEOINDUCTION IN RATS IS NOT ALTERED BY FIBRIN SEALANT

The angiogenic and fibrogenic activities of fibrin sealant (Tisseel) s uggest that it could enhance osteoinductivity during the first days af ter implantation. To test this hypothesis, the osteoinductivity of sea led and unsealed bone matrix gelatin was tested by implantation into r at abdominal wall muscle pouches for two to ten days. A sponge of coll agen with or without fibrin sealant was used for control. Alkaline pho sphatase (ALPase) was employed to quantify osteoinduction, and myelope roxidase (MPO) was used to determine the inflammatory reaction. Plain histologic analysis of bone matrix gelatin implants at Days 2, 4, and 10 did not demonstrate any significant differences between sealed and nonsealed implants. Histologic analysis at Day 21 confirmed the osteoi nductivity of the implant. The combination of bone matrix gelatin and fibrin sealant induced an early significant increase in ALPase activit y, which could be interpreted as early induction of histologically und etectable osteogenesis. A simultaneous increase in the level of MPO su ggested that the bone matrix gelatin/fibrin sealant-induced ALPase rea ction might be caused by an inflammatory process, but neutrophil count ing did not correlate to the MPO data. Morphometry, however, seems to be insufficient to assay a heterogenous histologic distribution of sin gular cells. It is proposed that the ALP/MPO ratio may be used as an i nflammation-independent marker of osteogenesis. This study does not su pport the notion of an osteoinductive potency of fibrin sealant per se ; however, it is clear that fibrin sealant does not impair bone matrix gelatin-dependent osteoinduction.