title: Modified keratin sponge: binding of bone morphogenetic protein-2 and osteoblast differentiation.
abstract: A keratin sponge was chemically modified to obtain carboxyl and amino sponges by the alkylation of a large amount of active SH group on keratin proteins with iodoacetic acid and 2-bromoethylamine, respectively. The carboxyl sponge having a large amount of carboxyl group was a scaffold that could bind significant amounts of basic bioactive proteins, such as lysozyme and bone morphogenetic protein (BMP)-2, and drugs. Lysozyme (maximum 3.7 mg), a model of basic cytokines such as BMP-2, was absorbed by the carboxyl sponge (4.8 mg), but not by the amino sponge. The lysozyme was rapidly released from the carboxyl sponge in a buffer containing at a concentration higher than 0.5 M, but at 0.15 M, near the physiological ionic strength, after initial burst (only 11%), no significant release was observed (15%, 48 h). BMP-2 also bound the carboxyl sponge. The preosteoblast cells grown inside the BMP-2-loaded sponge differentiated, whereas those grown outside the sponge did not, suggesting that no significant amount of BMP-2 leaked into the surrounding media. The effects of BMP-2 were confined inside modified keratin sponge. Therefore, using in vivo, we expect that only internal osteogenesis will be induced and that no external heterotopis ossification will be induced.
authors.affiliation: Department of Bioengineering, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan. tatibana@bioa.eng.osaka-cu.ac.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Tachibana
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nishikawa
authors.forename: Masaaki
authors.initials: M
authors.lastname: Nishino
authors.forename: Sumika
authors.initials: S
authors.lastname: Kaneko
authors.forename: Toshizumi
authors.initials: T
authors.lastname: Tanabe
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Yamauchi
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000737:chemistry / Q000378:metabolism*; D002454:Cell Differentiation; D002460:Cell Line; D007633:Keratins / Q000737:chemistry / Q000378:metabolism*; D051379:Mice; D009113:Muramidase / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology*; D010012:Osteogenesis; D016212:Transforming Growth Factor beta / Q000737:chemistry / Q000378:metabolism*
chemical_list: D001672:Biocompatible Materials; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D016212:Transforming Growth Factor beta; D007633:Keratins; D000469:Alkaline Phosphatase; D009113:Muramidase