Corneal Tissue Engineering: An <em>In Vitro</em> Model of the Stromal-nerve Interactions of the Human Cornea

Abstract

Tissue engineering has gained substantial recognition due to the high demand for human cornea replacements with an estimated 10 million people worldwide suffering from corneal vision loss1. To address the demand for viable human corneas, significant progress in three-dimensional (3D) tissue engineering has been made2,3,4. These cornea models range from simple monolayer systems to multilayered models, leading to 3D full-thickness corneal equivalents2. However, the use of a 3D tissue-engineered cornea in the context of in vitro disease models studied to date lacks resemblance to the multilayered 3D corneal tissue structure, function, and the networking of different cell types (i.e., nerve, epithelium, stroma, and endothelium)2,3.In addition, the demand for in vitro cornea tissue models has increased in an attempt to reduce animal testing for pharmaceutical products. Thus, more sophisticated models are required to better match systems to human physiological requirements, and the development of a model that is more relevant to the patient population is absolutely necessary. Given that multiple cell types in the cornea are affected by diseases and dystrophies, such as Keratoconus, Diabetic Keratopathy, and Fuchs, this model includes a 3D co-culture model of primary human corneal fibroblasts (HCFs) from healthy donors and neurons from the SH-SY5Y cell line. This allows us for the first time to investigate the interactions between the two cell types within the human corneal tissue. We believe that this model could potentially dissect the underlying mechanisms associated with the stromal-nerve interactions of corneal diseases that exhibit nerve damages. This 3D model mirrors the basic anatomical and physiological nature of the corneal tissue in vivo and can be used in the future as a tool for investigating corneal defects as well as screening the efficacy of various agents before animal testing.

Corneal Epithelial–Stromal Fibroblast Constructs to Study Cell–Cell Communication in Vitro

“…We have previously developed a 3D model of the human corneal stroma that relied upon self-assembly of an ECM produced by hCFs in situ over 4 weeks [16,17]. This 3D stromal model has been applied in the study of endothelial [30] and neuronal [41] cell interactions, as well as in investigations of the effects of hypoxia [42,43] and corneal disease (e.g., keratoconus [44] and diabetes [45]). In this study, we report the development and characterization of corneal epithelial-stromal co-cultures that are constructed using the 3D in vitro model with an overlaying epithelial layer.…”

The Human Tissue-Engineered Cornea (hTEC): Recent Progress

“…Further advances include the application of a self-assembled stromal model. This relies on ECM production by corneal fibroblasts and the addition of a bone-marrow-derived neuroblastoma cell line (SH-SY5Y), differentiated into a neuronal lineage [ 238 ]. Furthermore, the ECM plays a fundamental role in regulating the growth and functionality of peripheral nerves [ 239 , 240 ].…”

Three-Dimensional Human Cell Culture Models to Study the Pathophysiology of the Anterior Eye

“…This model was also used to study keratoconus [ 85 ] and therapies against corneal diabetes [ 86 ]. Subsequently, Sharif et al included nerves to study their interaction with fibroblasts [ 87 ].…”