Introduction: Dry age-related macular degeneration (AMD) is the leading cause of blindness in people over 60 years, and to-date has no effective treatment1,2. Researchers have used electrospun membranes to support retinal pigment epithelium cells (RPEs) to treat dry AMD3-6. It remains unclear if mimicking the microenvironment of native Bruch’s membrane (BM) can support functional RPEs. Our aim was first, to fabricate electrospun nanofibrous membranes (ENMs) with physical properties similar to the ICL. Second, evaluate invitro laminin adsorption on the ENMs and their subsequent influence on RPE proliferation and functionality, and third, evaluate invivo the biocompatibility of the ENMs.
Results: ENMs with average fiber diameters ≤ 70nm, thicknesses < 1.4μm and porosities > 45%, were fabricated via electrospinning, thereby mimicking the ICL (Fig1A). The 70nm fiber diameter helped create ENMs with high surface roughnesses (Fig1B). Due to a thermodynamically favorable state, PLLA based ENMs adsorbed high amounts of laminin (Fig1C), which in short-term culture, significantly increased RPE attachment and proliferation (Fig1D). qPCR (Fig2A) and immunohistochemical (Fig2B) assessments showed the ENMs to support expression of signature RPE markers. In long-term culture, PLLA based ENMs supported functional RPE monolayers, which exhibited polygonal morphology and apical microvilli (Fig1E), high TER (Fig1F) and phagocytic activity (Fig2B). Further, PLLA based ENMs were successfully implanted (Fig2C), and well tolerated without adverse biocompatibility issues in the sub-retinal space of rdy rats, in the absence of immune suppression (Fig3D). We successfully fabricated PLLA based ENMs, coated with laminin, mimicking the top 2 layers of native BM. These ENMs not only accelerated RPE cell proliferation, but also promoted RPE functionality. Biomimetic, laminin coated PLLA based ENMs are therefore a potential candidate to be used as scaffolds for the transplantation of RPEs for treating dry AMD.