(658b) 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 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 protein named (EL18-9Y)₂ was designed and cloned.  The protein contains two cassettes, each containing 18 elastin-like pentapeptides followed by an adhesive domain containing 9 tyrosine residues. (EL18-9Y)₂ was expressed in E. coli and then purified with nickel affinity chromatography (>100 mg/L yield, >90% purity).  Following enzymatic conversion to produce the adhesive DOPA residues from tyrosines, (EL18-9Y)₂ demonstrated increased adsorption to glass compared to BSA or unconverted (EL18-9Y)₂.  In addition, human umbilical vein endothelial cells (HUVECs) cultured on an (EL18-9Y)₂-coated coverslip showed >98% viability after 2 days, which indicates that the protein is cytocompatible.  Lap shear testing is currently being performed to assess the protein’s bulk adhesive properties.  In summary, (EL18-9Y)₂ is a promising new material that 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 a coating for cell attachment or a scaffold for tissue engineering.