The development of fibrin-based scaffolds for spinal cord regeneration

The goal of this project is to develop and characterize fibrin-based tissue engineering scaffolds that can serve as a physical bridge for the regeneration of injured tissues, such as spinal cord lesions, and provide a vehicle for the delivery of neurotrophic factors. We have developed a fusion protein that links two domains to the N-terminus of neurotrophin-3 (NT-3). The first domain contains a transglutaminase substrate (TG) that mediates the cross-linking of the fusion protein to the fibrin matrix. The second domain is a plasmin substrate (P); theoretically, the enzymatic cleavage of this domain by plasmin will result in the release of NT-3 to cellular targets. Because plasmin is activated as cells migrate into the fibrin matrix, this fusion protein represents a mechanism for delivering NT-3 based on cellular demand. We report the OCR synthesis of the gene for the TG-P-NT3 fusion protein and the expression of the protein in E. coli. The biological activity of the refolded protein was assayed based on its ability to enhance neurite extension from explanted chick embryo dorsal root ganglia (DRGs). The cell-mediated delivery of NT-3 from fibrin gels could promote the regeneration of axons after spinal cord injury.