(695e) Adhesive Elastin-Based Proteins As Soft Tissue Glues

Each year, millions of major surgeries are performed worldwide. Many of these major surgeries involve suturing of tissue, which results in additional damage to the tissue and slows the healing process. Surgical adhesives are a promising alternative to sutures. To be a successful surgical adhesive, a product must be: biocompatible, set in a wet environment, and have proper adhesive and cohesive properties. In addition, a soft tissue surgical adhesive must also be flexible to prevent excessive stress on surrounding tissue. Unfortunately, most modern adhesives lack at least one of these characteristics.

The goal of this project is to utilize protein engineering to develop and characterize a biomimetic soft tissue surgical adhesive. The protein-based adhesive will contain two domains: a structural domain that provides flexibility and an adhesive domain that provides the ability to adhere in wet environments. The structural domain is inspired by elastin, a protein that provides elastic properties to tissues such as skin, blood vessels, and ligaments.  The adhesive domain is inspired by mussel adhesive proteins (MAPs), which have the ability to bond underwater to nearly any material. MAPs contain numerous 3,4-dihydroxyphenyl-L-alanine (DOPA) residues, a chemical moiety that provides adhesion and cohesion through a number of mechanisms.  Together, the elastin-based domain and the mussel-inspired domain will provide the characteristics necessary for an effective surgical adhesive.

Using standard molecular biology techniques, a family of proteins has been designed.  Each protein contains elastin-like pentapeptides in combination with numerous tyrosine residues.  Following expression in E. coli and subsequent purification, the proteins will undergo enzymatic conversion to produce the adhesive DOPA residues from tyrosines. To be successful soft-tissue surgical adhesives, the proteins must be biocompatible, have strong bulk adhesive strength, and a low elastic modulus.  A LIVE/DEAD fluorescence assay will be utilized to assess protein cytotoxicity.  Lap shear adhesion testing will be used to examine bulk adhesive strength.  Finally, uniaxial tensile testing of crosslinked protein hydrogels will be performed to assess the elastic modulus of the adhesive.  Initial results show high cytocompatibility (>98% viability) and significant bulk adhesive strength on aluminum (approximately 1 MPa).  In summary, this new family of flexible adhesive proteins combines the mechanical properties of elastin and the adhesive properties of MAPs.  Its unique properties are ideal for application as a soft tissue surgical adhesive, as well as coatings for cell attachment or scaffolds for tissue engineering.