Genipin is a naturally occurring cross-linker derived from the plant Gardenia jasminoides that has low cytoxicity and can form stable and biocompatible cross-linked products . Many laboratory studies have been conducted into the use of genipin cross-linking to enhance the biostability of collagen/chitosan scaffolds for ocular surface reconstruction [2-3], myocardial  and cartilage tissue regeneration  and numerous other applications. Its ability to strengthen the sclera has also highlighted the potential usefulness of genipin cross-linking in stabalising ocular tissue to prevent myopia progression . In terms of the cornea, laboratory studies have also shown that removal of the corneal epithelium, followed by a 30-minute application of 0.25% genipin produces a stiffening effect that is comparable to that achieved with riboflavin/UVA cross-linking . However, unlike riboflavin/UVA cross-linking which results in a loss of corneal cells (keratoyctes) from the anterior 300μm of the corneal stroma, minimal keratocyte apoptosis occurs immediately after genipin cross-linking , and even after 14-days there is only a small amount of keratocyte loss in the anterior 50μm of the stroma . Further to this, significant corneal flattening has been recorded in genipin-treated rabbit corneas at 60-day follow-up, with minimal blue staining of the cornea (caused by the blue pigment of genipin) and no damage to the endothelium . Although the potential of this cross-linker is clear and further testing is warranted, the dose-dependent discolouration of the transparent cornea may prove to be a limiting factor in its clinical usefulness for the management of corneal disorders, such as keratoconus.
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