Tropoelastin: a versatile, bioactive assembly module

Abstract

Elastin provides structural integrity, biological cues and persistent elasticity to a range of important tissues, including the vasculature and lungs. Its critical importance to normal physiology makes it a desirable component of biomaterials that seek to repair or replace these tissues. The recent availability of large quantities of the highly purified elastin monomer, tropoelastin, has allowed for a thorough characterization of the mechanical and biological mechanisms underpinning the benefits of mature elastin. While tropoelastin is a flexible molecule, a combination of optical and structural analyses has defined key regions of the molecule that directly contribute to the elastomeric properties and control the cell interactions of the protein. Insights into the structure and behavior of tropoelastin have translated into increasingly sophisticated elastin-like biomaterials, evolving from classically manufactured hydrogels and fibers to new forms, stabilized in the absence of incorporated cross-linkers. Tropoelastin is also compatible with synthetic and natural co-polymers, expanding the applications of its potential use beyond traditional elastin-rich tissues and facilitating finer control of biomaterial properties and the design of next-generation tailored bioactive materials.

Keywords: Biomaterials; Elasticity; Elastin; Structure; Tropoelastin.

Figure 1

A) Structural features of the tropoelastin monomer; B) Cell interactive C-terminal sequence –RKRK and; C) assembly model showing the N- to C- terminal interaction. Adapted from [32].

Figure 2

The assembly of a single tropoelastin monomer through defined stages, resulting in increasingly sophisticated intermediates. The in-depth understanding of this process has facilitated the development of diverse tropoelastin-based biomaterials including: A) classical hydrogels; B) electrospun fibers; C) pH stabilized materials [90] and; D) Methacrylated tropoelastin hydrogels, adapted from [100].