Different types of stem cells have been used in various ways in several research projects in order to find the optimal procedure to regenerate the human corneal stroma. It included several approaches which can be classified as intrastromal implantation of stem cells (1) alone, (2) together with a biodegradable scaffold, (3) with a non-biodegradable scaffold, or (4) with a decellularized corneal stromal scaffold. In fact, the complex structure of the corneal stroma has not been yet replicated, and there are well known drawbacks to the use of synthetic scaffold-based designs. Recently, several corneal decellularization techniques have been described, which provide an acellular corneal extracellular matrix (ECM). These scaffolds have gained attention in the last few years as they provide a more natural environment for the growth and differentiation of cells when compared with synthetic scaffolds. In addition, components of the ECM are generally conserved among species and are tolerated well even by xenogeneic recipients. Keratocytes are essential for remodeling the corneal stroma and for normal epithelial physiology. This highlights the importance of transplanting a cellular substitute together with the structural support (acellular ECM) to undertake these critical functions in corneal homeostasis. To the best of the investigators knowledge, all attempts to repopulate decellularized corneal scaffolds have used corneal cells, but these cells have major drawbacks that preclude their autologous use in clinical practice (damage of the donor tissue, lack of cells and inefficient cell subcultures), thus the efforts to find an extraocular source of autologous cells. A recent study by the investigators has shown a perfect biointegration of human decellularized corneal stromal sheets (100µm thickness) with and without h-ADASC colonization inside the rabbit cornea in vivo, without observing any rejection response despite the graft being xenogeneic. The investigators also demonstrated the differentiation of h-ADASCs into functional keratocytes inside these implants in vivo, which then achieved their proper biofunctionalization. According to the investigator's opinion the transplant of stem cells together with decellularized corneal ECM would be the best technique to effectively restore the thickness of a diseased human cornea, like in keratoconus. Through this technique, and using extraocular mesenchymal stem cells from patients, it is possible to transform allergenic grafts into functional autologous grafts, theoretically avoiding the risk of rejection.