The in vitro elution of BMP-7 from demineralized bone matrix.
Demineralized bone matrix (DBM) grafts induce new bone formation by locally releasing matrix-associated growth factors, such as bone morphogenetic proteins (BMPs), to the surrounding tissue after implantation. However, the release kinetics of BMPs from DBM lack characterization. Such information can potentially help to improve processing techniques to maximize graft osteoinductive potential, as well as increase understanding of the osteoinductive process itself. We produced DBM with three particle size ranges from bovine cortical bone, i.e., <106, 106-300, and 300-710 μm and extracted 1.5 g of each size range in 40 ml of Sorensen's buffer at room temperature for up to 168 h. The BMP-7 concentration of the DBM and the buffer were measured at each time point using enzyme-linked immunosorbant assay. Based on measurement of the concentration of BMP-7 in the buffer, the 0-8 h elution rate was high, i.e., 3.3, 2.9, and 2.2 ng BMP-7/g DBM h, and for the 8-168 h interval was much lower, at 0.039, 0.15, and 0.11 ng BMP-7/g DBM h for the three size ranges, respectively. By 168 h, there was no indication that elution was nearing completion. Measurement of the residual BMP-7 remaining in the DBM as a function of time yielded unexpected results, i.e., after the BMP-7 content of the DBM declined for the first 4-6 h, it paradoxically increased for the remaining interval. We propose a two-compartment model to help explain these results in terms of the possible distribution of BMP-7 in bone matrix.
Biomet, Inc., 56 E. Bell Drive, Warsaw, IN 46581, USA. billsp@uic.edu
William S
WS
Pietrzak
Michael
M
Dow
Jerry
J
Gomez
Meghan
M
Soulvie
George
G
Tsiagalis
D001672:Biocompatible Materials; D018775:Bone Demineralization Technique; D001857:Bone Matrix / Q000378:metabolism*; D055419:Bone Morphogenetic Protein 7 / Q000378:metabolism*; D006801:Humans; D016212:Transforming Growth Factor beta / Q000378:metabolism
C525819:BMP7 protein, human; D001672:Biocompatible Materials; D055419:Bone Morphogenetic Protein 7; D016212:Transforming Growth Factor beta