Highly concentrated collagen solutions leading to transparent scaffolds of controlled three-dimensional organizations for corneal epithelial cell colonization

Abstract

This study aimed at controlling both the organization and the transparency of dense collagen scaffolds making use of the lyotropic mesogen properties of collagen. Cholesteric or plywood-like liquid crystal phases were achieved using mixtures of acetic and hydrochloric acids as solvents. The critical pH at which the switch between the two phases occurred was around pH = 3. The use of the two acids led to fibrillated collagen I scaffolds, whose visual aspect ranged from opaque to transparent. Rheological investigations showed that viscoelastic properties of the plywood-like solutions were optimized for molding due to faster recovery. They also confirmed the correlation between the elastic modulus and the diameter of collagen fibrils obtained after fibrillogenesis under ammonia vapor. Human corneal epithelial cells, grown from donor limbal explants, were cultured both on transparent plywood-like matrices and on human amniotic membranes for 14 days. The development of corneal epithelium and the preservation of epithelial stem cells were checked by optical microscopy, colony formation assay, immuno-fluorescence and quantitative polymerase chain reaction. A higher level of amplification of limbal stem cells was obtained with collagen matrices compared with amniotic membranes, showing the high biocompatibility of our scaffolds. We therefore suggest that collagen solutions presenting both plywood-like organization and transparency might be of interest for biomedical applications in ophthalmology.

Topotactic Fibrillogenesis of Freeze-Cast Microridged Collagen Scaffolds for 3D Cell Culture

“…Nevertheless, the scaffold was left in the buffer medium for 2 weeks before use to ensure complete stabilized fibrillogenesis of the scaffolds as collagen matrix can remodel for days after neutralization. 34,35 From a morphological standpoint, the macroporous materials presented here could be compared to collagen sponges. However, collagen sponge lack the fibrillary structure attained here.…”

Interrogating helical nanorod self-assembly with fractionated cellulose nanocrystal suspensions

“…where λ is the wavelength in air, n is the average cholesteric refractive index and θ is the incidence angle to m. Cholesteric Bragg reflection can be seen in the strikingly coloured and circularly polarised reflections from cuticles of certain beetles 3,4 , and even from some fruits 5,6 , revealing their helical arrangement of fibres of chitin and cellulose, respectively. In fact, cholesteric helical self-assembly can be found across a large range of biomaterials 7 , providing advantages beyond optics for, e.g., optimised packing of DNA/RNA [8][9][10] and spectacular mechanical properties of composites built around collagen 11,12 , amyloid 13 , chitin 14,15 or cellulose 16,17 . Attempts to mimic this structuring via self-assembly in cholesteric colloidal nanorod suspensions, for instance by drying cholesteric suspensions of cellulose nanocrystals (CNCs) 18 , often yield non-uniform films reflecting a range of colours with imperfect circular polarisation, and reproducibility and tunability are challenging 1,[19][20][21][22][23][24] .…”

Poly-l/dl-lactic acid films functionalized with collagen IV as carrier substrata for corneal epithelial stem cells

“…Col IV has been described in some studies not only as an adhesion protein, but also as a biomaterial that supports the culture of LESCs and stromal cells. Several types of collagen, such as collagen I (Vitrigel) [53], collagen III [16], or collagen together with chitosan [54] have been used for the in vitro reconstruction of the corneal epithelium [55]. Moreover, some studies have demonstrated the use of a compressed collagen matrix containing embedded fibroblasts, which simulate the corneal stroma, as substrates for LESCs [21,24,56].…”