In this project, natural matrix-based cell delivery vehicles for retinal progenitor cell (RPC) delivery to the subretinal space will be developed and tested, providing a novel therapeutic strategy for retinal regeneration. Specifically, interphotoreceptor matrix (IPM), the specialized matrix that surrounds the outer segments of rod and cone photoreceptors and occupies the space between the photoreceptors and retinal pigment epithelium, will be used as a base material for cell delivery vehicles. The developmental age of the IPM and removal of molecules inhibitory to neural regeneration (chondroitin sulfate proteoglycans) will be explored as key factors in creating an environment promoting seeded cell migration, integration into host retina, and differentiation. Implantation of RPCs into the subretinal space has recently shown tremendous promise as a therapy capable of restoring visual function. However, major barriers to the success of this therapy include extremely low levels (<1%) of cell integration into host retina and high levels of implanted cell death. A promising approach has been the use of synthetic polymers as scaffolds for cell-polymer composites which are implanted;these materials have resulted in 16-fold enhancement in cell survival, but levels are still inhibitively low. It is hypothesized that precise structural and biochemical cues provided by native IPM will promote integration of seeded RPCs into host retina, retinal regeneration, and restoration of visual function. The cell delivery vehicles developed in this project could provide a feasible clinical treatment for retinal degeneration associated with a wide variety of diseases, including macular degeneration and retinopathy of prematurity.
The specific aims of the project, designed to test the central hypothesis, include developing and biochemically/ structurally characterizing IPM based cell delivery vehicles, testing in vitro cellular response to developed vehicles, and testing ability to promote retinal regeneration and visual function in vivo. In the first specific aim, procedures for isolating, processing, and characterizing IPM vehicles will be developed. IPM will be isolated from adult and fetal porcine eyes, processed to remove residual cellular material, treated for removal of chondroitin sulfate proteoglycans, and characterized structurally and biochemically. In the second aim, RPCs will be seeded onto IPM vehicles and cultured in a retinal explants model. The attachment, proliferation, alignment, expression of photoreceptor-specific markers, and integration into cultured retina will be studied. Finally, in aim 3, promising IPM based vehicles will be seeded with RPCs and implanted into the subretinal space of mice. Cell survival, differentiation, integration into host retina, and ability to promote retinal regeneration and visual function will be assessed. The research team has the interdisciplinary expertise essential to ensure success in meeting the overall objective, including a chemical engineer with expertise in biomaterial development, a neuroscientist with extensive experience in cell-polymer retinal regeneration strategies, and a neuroscientist with expertise in neural regeneration and stem/progenitor cells.
This project will result in development of a novel, natural matrix-based cell delivery vehicle for delivery of retinal progenitor cells (RPCs) to the subretinal space to promote retinal regeneration and restoration of visual function in patients suffering from retinopathies including macular degeneration and retinopathy of prematurity. While the strategy of progenitor cell delivery to the subretinal space has demonstrated hugely promising results, including some vision rescue, major barriers to success are low levels of RPC integration (<1%) into host retina and high levels of RPC death. Here, the natural structural and biochemical cues provided by native interphotoreceptor matrix (IPM) will be used to promote RPC survival and integration into adjacent host retina.
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