Controlled Assembly of Fibronectin Nanofibrils Triggered by Random Copolymer Chemistry

Abstract

Fibronectin fibrillogenesis is the physiological process by which cells elaborate a fibrous FN matrix. Poly(ethyl acrylate), PEA, has been described to induce a similar process upon simple adsorption of fibronectin (FN) from a protein solution -in the absence of cells -leading to the so-called material-driven fibronectin fibrillogenesis. Poly(methyl acrylate), PMA, is a polymer with very similar chemistry to PEA, on which FN is adsorbed keeping the globular conformation of the protein in solution. We have used radical polymerisation to synthesise copolymers with controlled EA/MA ratio seeking to modulate the degree of FN fibrillogenesis. The physico-chemical properties of the system were studied using dynamicmechanical analysis, differential scanning calorimetry and water contact angle. Both the degree of FN fibrillogenesis and the availability of the integrin binding region of FN directly depend on the percentage of EA in the copolymer, whereas the same total amount of FN was adsorbed regardless the EA/MA ratio. Cell morphology adhesion and differentiation of murine C2C12 were shown to depend on the degree of FN fibrillogenesis previously attained on the material surface. Myogenic differentiation was enhanced on the copolymers with higher EA content, i.e. more interconnected FN fibrils.

Material-driven fibronectin assembly for high-efficiency presentation of growth factors

“…In addition, the phenomenon is rapid and allows FN organization within a time scale of ~1 min ( 28 ). Further, we have recently shown that the combination of EA and MA in a random copolymer modulates the interconnection of FN nanonetworks in dependence of the composition of the system ( 29 ). …”

Role of chemical crosslinking in material-driven assembly of fibronectin (nano)networks: 2D surfaces and 3D scaffolds

“…These results suggest a close dependence between the mobility of polymer chains and the FN organization on the surface [23], [27]. When the amount of crosslinker increases, T g rises monotonically, reducing surface mobility.…”

“…The main contribution of this work is that it shows that PEA-based 3D scaffolds sustain the organization of the fibronectin in their pores into physiological-like (nano)networks in the same way as in 2D substrates and fibres, the so-called 2.5D environments [13], [23], [24], [25], [26], [27], [33].…”

“…As consequence of protein-material interactions, a physiological-like FN (nano)network is organised upon simple adsorption of FN from a protein solution [23], [24]. Poly(ethyl acrylate) substrates (PEA) with a —CO 2 (CH 2 ) 2 H side chain promote highly interconnected FN fibrils that have been shown to be biologically active in terms of cell adhesion, signalling, matrix reorganization and cell differentiation [13], [25], [26], [27], [28], [29]. The FN (nano)network induced by PEA substrates enhances cell adhesion with a higher number of actin stress fibres and focal adhesion kinase activity.…”

“…The FN (nano)network induced by PEA substrates enhances cell adhesion with a higher number of actin stress fibres and focal adhesion kinase activity. Furthermore, FN provides greater exposure of cell binding domains (integrin binding regions), which translates into higher cell differentiation [26], [27].…”