Novel Collagen Membranes for the Reconstruction of the Corneal Surface

Abstract

No standardized biomaterial exists for the surgical treatment of persistent corneal erosions and ulcerations. We analyzed the suitability and biocompatibility of defined noncross-linked and UV/riboflavin cross-linked equine type I collagen membranes for the reconstruction of the corneal surface. Isolated human oral mucosa epithelial cells, a cell type in clinical use for the treatment of ocular surface diseases, were subcultivated on both types of membranes and examined concerning cell adhesion, proliferation, and differentiation. Biocompatibility was evaluated following superficial and intrastromal corneal transplantation in New Zealand white rabbits. In cell cultures all collagen membranes supported adhesion of oral mucosa epithelial cells leading to the formation of multilayered epithelial cell sheets. After intrastromal corneal implantation clinical signs of degradation were seen in all variants of collagen membranes, which was fastest in noncross-linked variants. The histological and ultrastructural level invasion of keratocytes and production of new collagen fibers inside the collagen membranes could be detected in noncross-linked variants. After superficial corneal implantation covering of the membranes by corneal epithelium over time was visible. Ultrastructural analysis showed a slower rate of degradation and less invading keratocytes in cross-linked variants compared with noncross-linked collagen membranes. Cross-linked and noncross-linked variants of the collagen membrane proofed to be suitable to serve as a carrier for epithelial stem cells in vitro and showed a high biocompatibility in vivo. These results indicate that the tested collagen membranes might be suitable for the reconstruction of the corneal surface in patients with nonhealing ulcerations. Whether membranes with faster or slower degradation properties are preferable for the treatment of persistent corneal ulcerations might depend on the underlying corneal pathology and the degree of concomitant inflammation.

Optimization of Corneal Epithelial Progenitor Cell Growth on Bombyx mori Silk Fibroin Membranes

“…For example, it has been reported that coating tissue culture plastic with collagen or fibronectin significantly increases the expansion of human corneal endothelial cell cultures [ 18 , 28 – 30 ]. Likewise, collagen or laminin coating enhances corneal epithelial cell attachment and migration in vivo and promotes increased stratification on polycarbonate membranes in vitro [ 31 , 32 ]. Furthermore, human corneal epithelial cells demonstrate significantly higher rates of wound closure when cultured on therapeutic contact lenses coated with vitronectin [ 33 ].…”

Report of the Inaugural Meeting of the TFOS i2 = initiating innovation Series: Targeting the Unmet Need for Dry Eye Treatment

“…Equine type I collagen membranes showed satisfactory re-epithelialization after ocular surface reconstruction in rabbits, and thus may be suitable for corneal surface reconstruction in patients with persistent, nonhealing ulcerations. 407 As transparency is an important concern in corneal surface reconstruction, keratin matrices made of human hair may serve as suitable matrices for corneal epithelial progenitor cells. Chemically processed and gamma sterilized, the keratin matrix is displays excellent transparency in vitro, suitable biomechanical properties, and good surgical applicability in suturing to the ocular surface.…”

Biomaterials for Regenerative Medicine Approaches for the Anterior Segment of the Eye

“…[43] Collagen type 1 (equine) has also been crosslinked using riboflavin and ultraviolet A (UVA), similar to the clinical treatment for keratoconus, and this has been shown to reduce the degradation of the collagen in vitro and after implantation intrastromally in rabbits. [44] Comparison of the cross-linked implants with untreated ones demonstrated that keratocytes invaded the untreated ones and laid down new collagen whereas in the cross-linked samples the keratocytes were observed on the surface of the implant only. …”