Biomimetic amniotic/silicone-based bilayer membrane for corneal tissue engineering

Amniotic membrane (AM) is an effective and widely used dressing in ocular injuries to reconstruct the cornea. Due to its low mechanical strength, high biodegradation rate, and difficult handling, its usage in medical interventions remains challenging. In this study, decellularized AM was covered with an ultrathin layer of Polydimethylsiloxane (PDMS) through a spinning method, which in turn resulted in an ultrathin (less than 80 mu m in thickness) bilayer corneal wound dressing membrane with improved mechanical behavior and transparency. The biomechanical, biological, and antibacterial properties of the bilayer membranes were measured both in vitro and in vivo. The optimized microsized membrane was applied on a corneal defect wound created in a rabbit model to evaluate the corneal healing. The results demonstrated a significant decrease in degradation rate, improved mechanical properties, and AM/PDMS transparency compared with AM. The corneal transparency improved until 21 days post-surgery in AM/PDMS group. Histological evaluations revealed that AM/PDMS had better epithelial delaminated cell morphology. The results of the RT-PCR showed a significant increase in MMP9, a significant decrease in Col1A1, TGF-beta 1, TNF-alpha and IL-6 in both AM and AM/PDMS compared with control wounds. This study suggessts AM/PDMS membrane as an excellent corneal wound dressing.