*Advances in Biomaterials for Corneal Regeneration DOI: http://dx.doi.org/10.5772/intechopen.106966*

non-immunogenic properties [40]. Photoactivated, in-situ forming antimicrobial silk-based hydrogels were developed for treating corneal injuries. Gentamicin-loaded methacrylated-silk (SilkMA) hydrogels adopted the corneal injury shape and gelled within a few minutes upon exposure to low-intensity UV. The mechanical strength, transparency, and water content approached those of the human cornea, and hydrogel inhibited the growth of *Staphylococcus aureus* and *Pseudomonas aeruginosa* for up to 72 h [41]. Silk-fibroin-based films (SF) were also complexed with lysophosphatidic acid (LPA) to form a functionalized graft for corneal endothelial cell (CEnCs) regeneration. The functionalized graft supported cell adhesion provided good biocompatibility and expressed CEnCs-specific genes and protein when tested in rabbit corneas [42]. A hybrid transparent fibrillar film made from SF/GelMA could be tuned as needed to form matrices with different properties by modifying the volume ratio of SNF to GelMA. The SNF/GelMA ratio of 30/70 was optimal and showed mechanical strength, transparency, and stability (reduction in degradation rate) that approximated the properties of the human cornea. The SNF/GelMA film supported cell attachment, spreading, and proliferation of stromal cells, making it an ideal candidate for corneal regeneration [43].

Recently, a study reported the upregulation of cytokine IL-1β, which induces undesirable phenotypic changes in keratocytes by downregulating the gene and protein expression of keratocyte corneal stromal markers: Keratocan, Lumican, Aldh3a1, and CD34. These markers play important role in maintaining corneal epithelial homeostasis and corneal transparency during normal conditions [44, 45]. The selective IKKβ inhibitor, TPCA-1, can reverse the phenotypic change and preserve the keratocyte phenotype in diseased corneas. Zhang and coworkers developed silk fibroin hydrogels with sustained release of TPCA-1, which accelerated in vivo wound healing, and increased keratocyte expression marker while supporting the regeneration of epithelium and stroma [46]. Thus, showing the promising potential of silk-fibroin-based hydrogel for corneal regeneration and drug delivery applications in vivo (**Table 1**).




## **Table 1.**

*Advances in the use of natural, biosynthetic, composite, and in-situ forming biomaterials for corneal reconstruction.*
