Cellular and nerve regeneration within a biosynthetic extracellular matrix for corneal transplantation

Abstract

Our objective was to determine whether key properties of extracellular matrix (ECM) macromolecules can be replicated within tissue-engineered biosynthetic matrices to influence cellular properties and behavior. To achieve this, hydrated collagen and Nisopropylacrylamide copolymer-based ECMs were fabricated and tested on a corneal model. The structural and immunological simplicity of the cornea and importance of its extensive innervation for optimal functioning makes it an ideal test model. In addition, corneal failure is a clinically significant problem. Matrices were therefore designed to have the optical clarity and the proper dimensions, curvature, and biomechanical properties for use as corneal tissue replacements in transplantation. In vitro studies demonstrated that grafting of the laminin adhesion pentapeptide motif, YIGSR, to the hydrogels promoted epithelial stratification and neurite in-growth. Implants into pigs' corneas demonstrated successful in vivo regeneration of host corneal epithelium, stroma, and nerves. In particular, functional nerves were observed to rapidly regenerate in implants. By comparison, nerve regeneration in allograft controls was too slow to be observed during the experimental period, consistent with the behavior of human cornea transplants. Other corneal substitutes have been produced and tested, but here we report an implantable matrix that performs as a physiologically functional tissue substitute and not simply as a prosthetic device. These biosynthetic ECM replacements should have applicability to many areas of tissue engineering and regenerative medicine, especially where nerve function is required.regenerative medicine ͉ tissue engineering ͉ cornea ͉ implantation ͉ innervation

Development of a hemicornea from human primary cell cultures for pharmacotoxicology testing

“…Collagen V is very important in the cornea for fibril diameter regulation and collagen VI is important for biomechanical characteristics and for keratocyte survival through its anti-apoptotic properties (Howell and Doane, 1998;Dirk, 2001;Minamitani et al, 2004). Other porous sponges have been described for cornea engineering, using either biomaterials (Li et al, 2003) or cross-linked collagens (Liu et al, 2006), but neither of these studies extensively described the newly synthesized ECM components.…”

Functionalised type-I collagen as a hydrogel building block for bio-orthogonal tissue engineering applications

“…These have now been grafted into 3 patients with high risks for rejection of conventionally transplanted human donor cornea. 17 In many instances, traditional chemical crosslinking techniques result in superior thermal and mechanical properties in comparison to physical crosslinking techniques. However, they tend to suffer from toxicity issues.…”

Microstructural Characteristics of Extracellular Matrix Produced by Stromal Fibroblasts

“…Later studies using a collagen and N-isopropylacrylamide copolymer hydrogel resulted in strengthening of the matrix, and both re-innervation and re-epithelialization of the implant was improved. 33,49,50 These studies suggest that hydrogels are one type of matrix that can be used for the development of a corneal replacement.…”