Development of new chimeric proteins for tissue engineering

Tissue engineering is an emerging !eld focused on the development of novel bioactive multifunctional materials that can be used to replace damaged and failing tissues. However, these biomaterials often present several problems such as loss of mechanical and/or biological properties and adverse immune responses. The use of natural polymers, such as proteins, provides a promising solution for these drawbacks. With advances in recombinant DNA technology and biotechnology, it is possible to design and produce new materials with different features by combining domains of different proteins in the same fusion protein. Spider dragline silk proteins have been suggested to have a large potential for many different biomedical applications due to its outstanding mechanical properties. In addition, spider silk is also biocompatible, hypoallergenic and completely biodegradable. Recently, silk copolymers based on repeats of the consensus sequence of MaSp1 (major ampullate spidroin I) from Nephila clavipes (6mer) have been fused with different functional proteins, peptides and protein motifs, showing promising results [1, 2]. In this project, by exploring the use of recombinant DNA techniques, we have constructed new silk copolymers composed of a structural motif (6mer) fused with functional domains namely GFOGER (from collagen type I) and FNII (!bronectin domain II); both are involved in cell adhesion and angiogenesis processes which are key factors in tissue engineering. Expression and puri!cation of the new chimeric proteins were successfully attained in Escherichia coli by means of auto-induction media. Furthermore, formic acid can be explored as a solvent for processing of the aforementioned recombinant copolymers. Results from the characterization of these biomaterials will be presented