title: Enzymatic crosslinking and degradation of gelatin as a switch for bone morphogenetic protein-2 activity.
abstract: Current therapies for tissue regeneration rely on the presence or direct delivery of growth factors to sites of repair. Bone morphogenetic protein-2 (BMP-2), combined with a carrier (usually collagen), is clinically proven to induce new bone formation during spinal fusion and nonunion repair. However, due to BMP-2's short half-life and its diffusive properties, orders of magnitude above physiological levels are required to ensure effectiveness. In addition, a high dose of this multifunctional growth factor is known to induce adverse effects in patients. To circumvent these challenges, we proposed and tested a new approach for BMP-2 delivery, by controlling BMP activity via carrier binding and localized proteolysis. BMP-2 was covalently bound to gelatin through site-specific enzymatic crosslinking using a microbial transglutaminase. Binding of BMP-2 to gelatin can completely switch off BMP-2 activity, as evidenced by loss of its transdifferentiating ability toward C2C12 promyoblasts. When gelatin sequestered BMP-2 is incubated with either microbial collagenase or tissue-derived matrix metalloproteinases, BMP-2 activity is fully restored. The activity of released BMP-2 correlates with the protease activity in a dose- and time-dependent manner. This observation suggests a novel way of delivering BMP-2 and controlling its activity. This improved delivery method, which relies on a physiological feedback, should enhance the known potential of this and other growth factors for tissue repair and regeneration.
authors: Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
authors: Kenrick
authors: K
authors: Kuwahara
authors: Josephine Y
authors: JY
authors: Fang
authors: Zhi
authors: Z
authors: Yang
authors: Bo
authors: B
authors: Han
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism*; D001842:Bone and Bones / Q000473:pathology; D002460:Cell Line; D002828:Choristoma / Q000473:pathology; D017364:Collagenases / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004798:Enzymes / Q000378:metabolism*; D005780:Gelatin / Q000378:metabolism*; D020782:Matrix Metalloproteinases / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D010012:Osteogenesis; D059748:Proteolysis; D051381:Rats; D013302:Streptomyces / Q000201:enzymology; D013997:Time Factors; D011503:Transglutaminases / Q000378:metabolism
chemical_list: D055396:Bone Morphogenetic Protein 2; D003432:Cross-Linking Reagents; D004798:Enzymes; D005780:Gelatin; D011503:Transglutaminases; D017364:Collagenases; D020782:Matrix Metalloproteinases