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Heat treatment of BMP‐2 depots on implant materials generates an immobilized layer of BMP‐2 with pronounced bioactivity
Author(s) -
Winkler Lars,
Bingmann Dieter,
Wiemann Martin
Publication year - 2006
Publication title -
journal of biomedical materials research part a
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.849
H-Index - 150
eISSN - 1552-4965
pISSN - 1549-3296
DOI - 10.1002/jbm.a.30822
Subject(s) - bone morphogenetic protein 2 , alkaline phosphatase , materials science , bone morphogenetic protein , incubation , noggin , bone morphogenetic protein 7 , in vitro , biophysics , biomedical engineering , biochemistry , biology , medicine , enzyme , gene
Bone cells seeded directly on depots of bone morphogenetic protein‐2 (BMP‐2) increase alkaline phosphatase (ALP) expression. Heating of such BMP‐2 depots to 100°C augmented the intensity of this local ALP induction. To understand this unexpected finding, we investigated the effect of heat treatment on BMP‐2 depots more closely. Using a novel bioassay based on ALP‐induction of remote cells, we found that the amount of released bioactive BMP‐2 from heat‐treated depots decays within days and could be described by an exponential function. From this function, we expected that pre‐incubation of BMP‐2 depots in culture medium for 4 weeks renders them insufficient to induce ALP. However, preincubated, heat‐treated depots still induced maximal ALP, unless treated with the selective BMP‐2 inhibitor noggin. Furthermore, heat treatment of BMP‐2 depots generated a layer of immunoreactive BMP‐2 at the surface of the carrier. In contrast, BMP‐2 was washed off completely if heat treatment of adsorbed protein was omitted. Results show that heat treatment generates both a soluble pool of BMP‐2 and a material‐bound layer of BMP‐2 in which the protein is protected against degradation. Therefore, heat treatment appears useful to locally immobilize BMP‐2 on various implant surfaces. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006