Mechanical Properties of Artificial Protein Matrices Engineered for Control of Cell and Tissue Behavior

Abstract

Genetic engineering methods were used for the preparation of artificial proteins containing sequences designed to reproduce essential features of the extracellular matrix (ECM). The long-term objective of the work is to develop matrices for use in the engineering of small-diameter vascular grafts. The CS5 domain of fibronectin provides binding sites for vascular endothelial cells, while an elastin-like repeat, [(VPGIG)2(VPGKG)(VPGIG)2], controls the mechanical properties and includes sites for covalent cross-linking. Bis(sulfosuccinimidyl) suberate and disuccinimidyl suberate were used to cross-link artificial ECM protein films for uniaxial tensile testing. Variation in the amount of cross-linker and protein weight fraction allowed preparation of films with Young's moduli ranging from 0.07 to 0.97 MPa. The weight fraction of protein in the hydrated, cross-linked films was measured to be between 0.2 and 0.4; the molecular weight between cross-links (M c) varied from 3000 to 38 000. The moduli and M c of the films span the ranges reported for natural elastins.

Synthesis and Characterization of Macroporous Thermosensitive Hydrogels from Recombinant Elastin-Like Polymers

“…[13][14][15] The enormous potential of this kind of protein polymer as a truly advanced material for a variety of biomedical applications, ranging from scaffolds for tissue engineering and regenerative medicine to cell-based microdevices, has boosted the exploration of the different ways that these peculiar polymers can be processed to achieve practical scaffolds and systems for use in different contexts, thereby showing the potential to improve the currently existing alternatives. In this regard, ELP scaffolds have been produced in the form of electrospun fibers, 16 hybrid hydrogels 17 and 2D films, 18 and ELP hydrogels have been producedbyphotoinitiation, 19 irradiation, 20,21 aminereactivity, [22][23][24][25][26] and enzymatic cross-linking by tissue transglutaminase. 27 However, due to the short history of this family and the fact that these materials are not commercially available, a great deal of fundamental knowledge regarding their properties is still lacking.…”

Injectable hydrogels

“…Furthermore, they can be efficiently produced in large scale through genetic modification in both eukaryotic and prokaryotic (E.coli) cell lines with reproducible peptide sequence and MWs. 198 ELPs have been widely used for TE applications such as cartilage, [199][200][201] vascular grafts, 202,203 soft tissue, 204,205 prevention of scarring after laminectomy, 206 and ocular 207 TE.…”

Elastin‐Like Macromolecules

“…For example, the cross-linked matrices of these polymers retain most of the mechanical properties of elastin [100,101], which becomes important when this behavior is accompanied by other interesting properties, such as biocompatibility, stimuli-responsive behavior, and the ability to self-assemble. Elastin-like systems and possible applications are further discussed in Section 5.5.…”