Helicoidal multi-lamellar features of RGD-functionalized silk biomaterials for corneal tissue engineering.
ABSTRACT RGD-coupled silk protein-biomaterial lamellar systems were prepared and studied with human cornea fibroblasts (hCFs) to match functional requirements. A strategy for corneal tissue engineering was pursued to replicate the structural hierarchy of human corneal stroma within thin stacks of lamellae-like tissues, in this case constructed from scaffolds constructed with RGD-coupled, patterned, porous, mechanically robust and transparent silk films. The influence of RGD-coupling on the orientation, proliferation, ECM organization, and gene expression of hCFs was assessed. RGD surface modification enhanced cell attachment, proliferation, alignment and expression of both collagens (type I and V) and proteoglycans (decorin and biglycan). Confocal and histological images of the lamellar systems revealed that the bio-functionalized silk human cornea 3D constructs exhibited integrated corneal stroma tissue with helicoidal multi-lamellar alignment of collagen-rich and proteoglycan-rich extracellular matrix, with transparency of the construct. This biomimetic approach to replicate corneal stromal tissue structural hierarchy and architecture demonstrates a useful strategy for engineering human cornea. Further, this approach can be exploited for other tissue systems due to the pervasive nature of such helicoids in most human tissues.
Article: Biomechanical and microstructural characteristics of a collagen film-based corneal stroma equivalent.[show abstract] [hide abstract]
ABSTRACT: The growth in refractive surgeries and corneal replacements has fueled interest in the development of a tissue-engineered cornea. This study characterizes the microstructure and biomechanical properties of film-based corneal stroma equivalents over time in culture. The increased collagen density in the films was hypothesized to result in improved mechanical properties both initially and over time. The microstructure of the film-based stromal equivalent was examined using atomic force microscopy and scanning electron microscopy; the mechanical properties, relaxed modulus, and ultimate tensile strength were quantified using uniaxial tensile testing. The dense, film-based stromal equivalent had a lamellae-like microstructure, which was notably different than the porous structure of sponges used previously. Seeded human corneal stromal fibroblasts remained on the surface of the film rather than migrating into the film and produced fibers of extracellular matrix with diameters of 35-75 nm. After an initial decrease during hydration, the relaxed modulus and ultimate tensile strength for fully hydrated collagen films were 0.4 +/- 0.2 MPa and 0.3 +/- 0.1 MPa, respectively. The mechanical properties of cell-seeded films mimicked those of control films. While further studies are needed to quantify the optical properties, the dense, lamellae-like structure of collagen films is a feasible scaffold for the development of tissue-engineered stroma.Tissue Engineering 07/2006; 12(6):1565-75. · 4.02 Impact Factor