Crosslinking of collagen gels by transglutaminase

Collagen is commonly used as a tissue-engineering scaffold, yet its in vivo applications are limited by a deficiency in mechanical strength. The purpose of this work was to explore the utilization of a unique enzymatic crosslinking procedure aimed at improving the mechanical properties of collagen-based scaffold materials. Type I bovine collagen gel was crosslinked by transglutaminase, which selectively mediates the chemical reaction between glutamine and lysine residues on adjacent protein fibers, thus providing covalent amide bonds that serve to reinforce the three-dimensional matrix. The degree of crosslinking was verified by thermal analysis and amine group content. The denaturation temperature of crosslinked collagen reached a maximum of 66 ± 1°C. The chemical reaction was confirmed to be noncytotoxic with respect to bone marrow stromal cells acquired from New Zealand White rabbits. Tube-shaped cellular constructs fashioned from crosslinked collagen and bone marrow stromal cells were found to have burst pressures significantly higher than their non-crosslinked analogs (71 ± 4 mmHg vs. 46 ± 3 mmHg; p < 0.01). Thus, the transglutaminase mediated reaction served to successfully strengthen collagen gels while remaining benign toward cells.