[Porous matrix and primary-cell culture: a shared concept for skin and cornea tissue engineering]

Skin and cornea both feature an epithelium firmly anchored to its underlying connective compartment: dermis for skin and stroma for cornea. A breakthrough in tissue engineering occurred in 1975 when skin stem cells were successfully amplified in culture by Rheinwald and Green. Since 1981, they are used in the clinical arena as cultured epidermal autografts for the treatment of patients with extensive burns. A similar technique has been later adapted to the amplification of limbal-epithelial cells. The basal layer of the limbal epithelium is located in a transitional zone between the cornea and the conjunctiva and contains the stem cell population of the corneal epithelium called limbal-stem cells (LSC). These cells maintain the proper renewal of the corneal epithelium by generating transit-amplifying cells that migrate from the basal layer of the limbus towards the basal layer of the cornea. Tissue-engineering protocols enable the reconstruction of three-dimensional (3D) complex tissues comprising both an epithelium and its underlying connective tissue. Our in vitro reconstruction model is based on the combined use of cells and of a natural collagen-based biodegradable polymer to produce the connective-tissue compartment. This porous substrate acts as a scaffold for fibroblasts, thereby, producing a living dermal/stromal equivalent, which once epithelialized results into a reconstructed skin/hemicornea. This paper presents the reconstruction of surface epithelia for the treatment of pathological conditions of skin and cornea and the development of 3D tissue-engineered substitutes based on a collagen-GAG-chitosan matrix for the regeneration of skin and cornea.