The tissue-engineered human cornea as a model to study the contribution of the integrin-mediated signal transaction pathways activated during corneal wound healing

摘要

Introduction: The cornea is localized at the outer surface of the eye. It is a transparent organ and highly specialized that is continually subjected to abrasive forces and occasional mechanical or chemical trauma because of its anatomical localization. A complete reepithelialization and the reorganization of a mature smooth stratified epithelium are essential in restoring the imaging properties of the cornea. We recently succeeded in tissue-engineering human cornea substitutes that mimic their in vivo counterpart in terms of cell phenotype and tissue architecture. Upon injury, the extracellular matrix (ECM) rapidly changes to promote wound healing through its interactions with integrins. We hypothesize that the remodelling of the ECM occurring during comeal wound healing causes the activation of very specific signal transaction mediators that favor faster closure profiling analyses provided evidence that wound closure is dependent in part on signalization by the PI3K/AM transaction pathway. Our goal is to proceed to the pharmacological inhibition or activation of the PI3K/Akt mediators Akt and CREB using the human tissue-engineered cornea (hTECs) as a model. Materials and Methods: The self-assembly approach was used to create hTECs as previously described They were wounded with a 8-mm diameter biopsy punch and deposited on another reconstructed human comeal slroma to allow wound closure on a natural ECM. The wounded tissues were then incubated with or without C646 (a CREB inhibitor) or with or without SC79 (an AKT activator). DMSO (the vehicle) was used alone as a negative control. Closure of the wounds was monitored over a period of 5 days to determine whether Akt activation and CREB inhibition will improve closure of the wounds. Results and Discussion: Data from the gene and protein profiling analyses indicate that important alterations in the expression of a few mediators is occurring primarily in the PI3K/AM pathways in response to the ECM remodeling taking place during wound healing of hTECs. Pharmacological inhibition of CREB with C646 considerably accelerated wound closure compared to control. Moreover, maintaining the wounded hTEC in the presence of both C646 and SC79 led to complete closure of the wounds in a much shorter time than C646 alone or the untreated controls. Conclusion: By simultaneously blocking the activation of CREB and enhancing the activation of Akt, we considerably altered the migratory properties of the comeal epithelial cells and substantially accelerated wound closure of injured hTEC thereby validating the use of the tissue-engineered human cornea as an outstanding model to study comeal wound healing. We hope this study will lead to progress in the clinical field of comeal blindness.