Soft Hydrogel Inspired by Elastomeric Proteins.

Antonietta Pepe,Lucia Maio,Luis Quintanilla-Sierra,Brigida Bochicchio,Alessandra Girotti,Angelo Bracalello,Francisco Javier Arias

doi:10.1021/acsbiomaterials.1c00817

Abstract

Elastin polypeptides based on -VPGVG- repeated motifs are widely used in the production of biomaterials because they are stimuli-responsive systems. On the other hand, glycine-rich sequences, mainly present in tropoelastin terminal domains, are responsible for the elastin self-assembly. In a previous study, we have recombinantly expressed a chimeric polypeptide, named resilin, elastin, and collagen (REC), inspired by glycine-rich motifs of elastin and containing resilin and collagen sequences as well. Herein, a three-block polypeptide, named (REC)3, was expressed starting from the previous monomer gene by introducing key modifications in the sequence. The choice was mandatory because the uneven distribution of the cross-linking sites in the monomer precluded the hydrogel production. In this work, the cross-linked polypeptide appeared as a soft hydrogel, as assessed by rheology, and the linear un-cross-linked trimer self-aggregated more rapidly than the REC monomer. The absence of cell-adhesive sequences did not affect cell viability, while it was functional to the production of a material presenting antiadhesive properties useful in the integration of synthetic devices in the body and preventing the invasion of cells.

Highlights

Polypeptides inspired by proteins generally constitute the matrices, usually known as scaffolds, used in tissue engineering and regenerative medicine
Elastin is well-known in the field because the conventional design of elastin polypeptides (ELPs) is usually based on [Val-Pro-GlyXaa-Gly] pentapeptide motif n-fold repeated, where Xaa could be any amino acid except proline.[6]
These regions are mainly present in the tropoelastin terminal domains and are responsible for elastin self-assembly.[11−13] Previous results on (XGGZG)[3] model peptides have shown that the residue type (X, Z = Val, Leu) and the exact position occupied by the residue in the motif are crucial in driving the selfaggregation and in defining the morphology of the formed nanostructures as well.[14]

Summary

Introduction

Polypeptides inspired by proteins generally constitute the matrices, usually known as scaffolds, used in tissue engineering and regenerative medicine. The presence of adhesion sites for promoting cell adhesion and spreading is very common.[1] Recombinant protein-inspired polypeptides offer the advantage of being highly biocompatible, with controlled molecular weight and low immunogenicity; they are generally preferred to natural polymers (alginate, chitin, and chitosan), synthetic polymers such as poly(ε-caprolactone) and polylactide, and copolymers such as poly(lactide-co-glycolide) and poly(lactide-co-ε-caprolactone).[2] Elastomeric proteins are widespread in living organisms from invertebrates (resilin in insects, byssus in mussels, and abductin of bivalve mollusks) to mammalians (elastin and titin present in connective tissues and vertebrate muscles).[3] Recently, resilin, present in arthropods, has captured attention for its outstanding mechanical properties and rubber-like characteristics.[4,5] Beyond resilin, elastin is well-known in the field because the conventional design of elastin polypeptides (ELPs) is usually based on [Val-Pro-GlyXaa-Gly] pentapeptide motif n-fold repeated, where Xaa could be any amino acid except proline.[6] This repeating motif, abundant in the central region of the tropoelastin molecule, exhibits intrinsic elasticity at the molecular level and is responsible for the inverse phase transition behavior acting as stimuli-responsive systems.[7−10] human tropoelastin is rich in glycine-rich sequences with the Xaa-Gly-Gly-Zaa-Gly motif containing Val and/or Leu as guest residues. The aim of the present work is the design and Received: June 18, 2021 Accepted: October 13, 2021 Published: October 22, 2021

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