Every year in the United States, over 33,000 corneal transplants are performed. The success rate for this procedure is fairly high (90% after two years) and although current access to donor tissue is adequate, the quality of tissue varies significantly which influences surgical outcomes. In addition, the proliferation of LASIK procedures, which disqualifies a cornea for transplantation, threatens to reduce the availability of donor corneas in the near future. In recent years, laudable attempts have been made to produce corneal equivalents by tissue engineering. These constructs have proven the concept that three layers of cells, resembling the epithelium, keratocytes and endothelium may be cultured into a collagen matrix. However, such constructs have only met with limited success because the stromal matrix, which provides the cornea with its unique (and critically important) mechanical and optical properties, has not been reproduced. Randomly oriented collagen gels, which represent the typical starting point for tissue engineered corneas, are not likely to be strong enough or clear enough for clinical use. In addition, expecting a significant in vivo remodeling response to integrate a partially functioning artificial cornea is not acceptable. The artificial construct should be functional at the time of implantation. For these reasons, we propose a stromal-centric approach toward the generation of an artificial cornea. We start by investigating precisely how fibroblastic cells produce organized tissue in vitro by tracking human fibroblasts live as they produce matrix on a long-term live imaging culture system. Then by combining bioengineering, biology, biomechanics and biochemistry an attempt will be made to produce biomimetic stromal lamellae (the building blocks for an artificial cornea). The method entails using the intelligence already """"""""encoded"""""""" into the collagen triple helix which produces organized arrays of fibrils simply by concentrating the monomers to induce liquid crystalline structure formation and fibrillogenesis. The resulting organized arrays of fibrils will be used as starting point for comprehensive investigation into the role of matrix molecules on collagen fibril morphology and spacing. Once our arrays are well-characterized, human corneal fibroblasts and human cord blood derived stem cells will be seeded into them and exposed to mechanical stimulation. We expect to induce differentiation in both populations of cells. Completion of this application will provide insight both to the basic science of understanding corneal stromal development and to achieving our ultimate goal, which is the ex vivo generation of a functional, biomimetic artificial cornea from natural components.
Completion of this application will provide insight both to the basic science of understanding corneal stromal development and to achieving our ultimate goal, which is the ex vivo generation of a functional, biomimetic artificial cornea from natural components. Given recent advances in biomaterials engineering and stem cell research (which are combined in this application) we expect to ultimately enhance the ability of clinicians to offer patients with significant morbidity viable alternative treatment options based on engineered tissue.
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