Antheraea mylitta Silk Films Support Corneal Re-epithelialisation as Inlay Grafts in Large-Sized Corneal Defect

Abstract

To evaluate the potential of Antheraea mylitta (AM) silk films for use as scaffolds in corneal defects. The study was conducted in New Zealand white rabbits. Thin transparent AM silk films were tested and compared with amniotic membrane and porcine small intestinal sub mucosa (SIS) as inlay graft for repair of corneal defect. Transparent AM silk films were prepared using standard method. Large-sized corneal defect in rabbit eye received films of either AM silk, amniotic membrane or SIS as inlay graft. Assessment of clinical healing by re-epithelialisation over the scaffolds was evaluated by histopathology, immunohistochemistry with cytokeratin-3 and scanning electron microscopy. The amniotic group had complete healing in 4/5 corneas by 7 days; the AM silk group showed complete healing in 2/5 eyes, and the SIS had 1/5 eye with complete healing. More than 50% healing was observed in 1/5 eyes with amniotic and AM silk scaffold and 4/5 eyes with SIS. Two corneas with AM silk showed less than 50% healing. Histopathology confirmed the re-epithelialisation, and positive immunostaining with cytokeratin-3 and scanning electron microscopy supported the re-epithelialisation over the scaffolds. This study demonstrates Antheraea mylitta silk films as promising scaffold for corneal repair. The healing potency though appreciable is less compared with the scaffolds in clinical use. Pursuit for an ideal corneal scaffold for corneal regeneration remains an unmet clinical need. Antheraea mylitta silk is endowed with natural RGD sequence which facilitates cell adhesion and has proven to be biocompatible in rabbit cornea. This study shows the potency of the silk scaffolds to support corneal re-epithelialisation when placed into large-sized corneal defects.