The cornea on the front surface of the eye is our window to the world. If transparency is compromised, visual impairment and even blindness can occur. There are 10 million people worldwide who are blinded by scarring of the cornea and are denied a sight saving corneal graft due to insufficient donor tissue availability. The ability to 'grow' components of a cornea in the laboratory would represent a very significant scientific and medical advance that could improve quality of life. As a first step towards this goal, we are working to address a condition called limbal epithelial stem cell (LESC) deficiency of the cornea, which causes painful, blinding corneal surface failure. An estimated 240 new cases of LESC deficiency occur annually in the UK. We have cultured and transplanted sheets of LESCs to improve vision in patients with chemical burns. However, many patients have very difficult to manage diseases requiring treatment with a substrate to aid cell survival, in our case human amnion. This approach can significantly improve quality of life and productivity in the workplace (patient personal communications) however, we have found the long-term therapeutic benefit to be variable. In part, we suspect, because cultured LESC sheets do not restore the normal LESC microenvironment or 'niche' destroyed by disease. Using a novel tissue engineering approach we have recently made simple constructs of the human corneal surface using protein, epithelial cells (including LESCs) and the fibroblasts that support them. Novel technology (Real Architecture for 3D Tissues - RAFT) is used to make a fibroblast-seeded collagen construct with surface toplology that mimics the in vivo stem cell niche, then corneal epithelial cells are seeded on the surface. Our data are very promising, the epithelial cells grow successfully and produce an epithelium. RAFT constructs are reproducible and have significant advantages over human amnion for LESC culture. Amnion is biologially variable and often (40% of cases) does not support the growth of healthy LESCs. We now wish to a) asses the physical and functional properties of RAFT and b) perform safety and efficacy studies so that we may proceed to first in man studies at Moorfields Eye Hospital (MEH) following this project. We already know that RAFT is strong enough to be handled and that text can be read through it. Here we will test actual mechanical strength as this must be sufficient to withstand surgery. Transparency will also be measured as RAFT should ideally be at least as transparent as the amnion we aim to replace if not better. The key driver behind this proposal is the need to establish if RAFT is safe to use and if it can improve the surface of a cornea with LESC deficiency. Without this information we cannot test RAFT in humans. Here we will work with colleagues to assess RAFT safety and efficacy in an established model of LESC deficiency. Our techniques and methods for producing RAFT constructs, presenting them to the surgeon in an accessible device and measuring clinical outcome in our model will be rigorously validated. If during this pre-clinical testing RAFT constructs can restore corneal transparency and maintain a healthy ocular surface, our data will be used to develop regulatory compliant standard operating procedures for the production of RAFT for future testing in man. This project is therefore essential to progress our research findings into clinical practice. If the project goes as planned, IoO have the experience and capacity to manufacture RAFT constructs in the 'Cells for Sight Cell Therapy Research Unit'. This new state of the art cleanroom facility, led by the applicant, is used to produce cell therapies for patients. If the project is successful, IoO and MEH will design a phase I/II safety and efficacy clinical trial to compare RAFT with LESC cultured on amnion.