Decellularization methods for developing porcine corneal xenografts and future perspectives.

Corneal transplantation is the only option to cure corneal opacities. However, there is an imbalance between supply and demand of corneal tissues in the world. To solve the problem of corneal shortage, corneal xenotransplantation studies have been implemented in the past years using porcine corneas. The corneal xenografts could come from (a) wild-type pigs, (b) genetically engineered pigs, (c) decellularized porcine corneas, and (d) decellularized porcine corneas that are recellularized with human corneal cells, eventually with patients' own cells, as in all type of xenografts. All approaches except, the former would reduce or mitigate recipient immune responses. Although several techniques in decellularization have been reported, there is still no standardized protocol for the complete decellularization of corneal tissue. Herein, we reviewed different decellularization methods for porcine corneas based on the mechanism of action, decellularization efficacy, biocompatibility, and the undesirable effects on corneal ultrastructure. We compared 9 decellularization methods including: (a) sodium dodecyl sulfate, (b) triton x-100, (c) hypertonic saline, (d) human serum with electrophoresis, (e) high hydrostatic pressure, (f) freeze-thaw, (h) nitrogen gas, (h) phospholipase A2 , and (i) glycerol with chemical crosslinking methods. It appears that combined methods could be more useful to perform efficient corneal decellularization.