Preparation of collagen/cellulose nanocrystals composite films and their potential applications in corneal repair.

As the main component of the natural cornea, collagen (COL) has been widely applied to the construction of corneal repair materials. However, the applications of collagen are limited due to its poor mechanical properties. Cellulose nanocrystals (CNCs) possess excellent mechanical properties, optical transparency and good biocompatibility. Therefore, in this study, we attempted to introduce cellulose nanocrystals into collagen-based films to obtain corneal repair materials with a high strength. CNCs were incorporated at 1, 3, 5, 7 and 10 wt%. The physical properties of these composite films were characterized, and in vitro cell-based analyses were also performed. The COL/CNC films possessed better mechanic properties, and the introduction of CNCs did not affect the water content and light transmittance. The COL/CNC films demonstrated good biocompatibility toward rabbit corneal epithelial cells and keratocytes in vitro. Moreover, the collagen films with appropriate ration of CNCs effectively induced the migration of corneal epithelial cells and inhibited the myofibroblast differentiation of keratocytes. A collagen film with 7 wt% CNCs displayed the best combination of physical properties and biological performance in vitro among all the films. This study describes a nonchemical cross-linking method to enhance the mechanical properties of collagen for use in corneal repair materials and highlights potential application in corneal tissue engineering.

Microgrooved collagen-based corneal scaffold for promoting collective cell migration and antifibrosis.

Collagen is a promising material for corneal tissue engineering. The surface topography of collagen is critical for cornea reconstruction and regeneration. Herein, we fabricated collagen films with microgrooved surface to investigate the effect of collagen film topography on corneal cell migration and antifibrosis. We found that the patterned films with microscale grooves could greatly affect the orientation, proliferation, migration, and gene expression of rabbit corneal epithelial cells and keratocytes. Compared with the natural cornea, the optimized collagen films with microgroove pattern show similar swelling performance, optical clarity, and biodegradability, which could efficiently promote the epithelial cell migration, accelerate wound healing process, and inhibit the fibrosis of keratocytes. These results suggest that collagen films with microgroove pattern are promising in corneal tissue engineering.

Engineering topography: Effects on corneal cell behavior and integration into corneal tissue engineering.

Cell-material interactions are important to tissue engineering. Inspired by the natural topographic structures on the extracellular matrix, a growing number of studies have integrated engineering topography into investigations of cell behavior on biomaterials. Engineering topography has a significant influence on cell behaviors. These cell-topography interactions play an important role in regenerative medicine and tissue engineering. Similarly, cell-topography interactions are important to corneal reconstruction and regeneration. In this review, we primarily summarized the effects of topographic cues on the behaviors of corneal cells, including cell morphology, adhesion, migration, and proliferation. Furthermore, the integration of engineering surface topography into corneal tissue engineering was also discussed.