Cornea and Ocular Surface Treatment

Abstract

In addition to being a protective shield, the cornea represents two thirds of the eye's refractive power. Corneal pathology can affect one or all of the corneal layers, producing corneal opacity. Although full corneal thickness keratoplasty has been the standard procedure, the ideal strategy would be to replace only the damaged layer. Current difficulties in corneal transplantation, mainly immune rejection and shortage of organ supply, place more emphasis on the development of artificial corneas. Bioengineered corneas range from prosthetic devices that solely address the replacement of the corneal function, to tissue-engineered hydrogels that allow regeneration of the tissue. Recently, major advances in the biology of corneal stem cells have been achieved. However, the therapeutic use of these stem cell types has the disadvantage of needing an intact stem cell compartment, which is usually damaged. In addition, long ex vivo culture is needed to generate enough cell numbers for transplantation. In the near future, combination of advanced biomaterials with cells from abundant outer sources will allow advances in the field. For the former, magnetically aligned collagen is one of the most promising ones. For the latter, different cell types will be optimal: 1) for epithelial replacement: oral mucosal epithelium, ear epidermis, or bone marrow- mesenchymal stem cells, 2) for stromal regeneration: adipose-derived stem cells and 3) for endothelial replacement, the possibility of in vitro directed differentiation of adipose-derived stem cells towards endothelial cells provides an exciting new approach.

Biointegration of corneal macroporous membranes based on poly(ethyl acrylate) copolymers in an experimental animal model

“…To repopulate the scaffolds, h-ADASCs were used, which have been shown to be a perfect source of autologous stem cells for the development of tissue-engineered corneas and avoid the limitations of corneal cells [6,8,25]. Despite their demonstrated potential, no significant differences between the groups with or without h-ADASCs were found, with any improvement in the clinical or histological biointegration and implant extrusion rate.…”

“…[6,8]. These cells have also shown immunomodulatory properties in syngeneic, allogeneic and even xenogeneic scenarios [10][11][12].…”

Corneal endothelium: developmental strategies for regeneration

“…Furthermore, the amount of stem cells found in these compartments is very low and may require prolonged ex vivo culture to generate enough cells for a successful transplant. 92 Therefore, further research is needed to find an alternative tissue source for corneal endothelial reconstruction, such as cells of extra-ocular origin.…”

Decellularized Human Cornea for Reconstructing the Corneal Epithelium and Anterior Stroma

“…A number of tissue engineering approaches have been investigated for the reconstruction of the whole cornea or its individual layers as an alternative to using cadaver corneal tissue for transplants. [1][2][3][4][5] Reconstruction of the corneal epithelium has been extensively studied with tissue-engineered corneal epithelium now in clinical use in selected academic centers worldwide. [6][7][8][9] In most clinical applications, a small population of corneal epithelial stem/progenitor cells from the limbus are expanded in culture on a substrate, typically a basement membrane such as human amniotic membrane.…”