Worldwide, corneal diseases primarily resulting from infection, trauma, and surgical complications are responsible for 6 to 8 million cases of blindness in human patients. In all of these cases, wound healing is an essential element to maintaining or restoring homeostasis and ensuring optimal visual outcomes. Corneal wound healing is a complex process wherein cells must simultaneously integrate multiple cues provided by the cytoactive factors in the soluble extracellular signaling environment as well as biophysical cues supplied by the extracellular matrix. Dysregulation or delay of this process can result in chronic non-healing wounds, haze formation, and visual compromise. Conventional medical and surgical treatments are sometimes insufficient in producing optimal outcomes. There is an urgent need for improved therapies in the treatment of corneal wounds. Therefore, a novel, versatile and generalizable engineering approach is proposed to promote favorable corneal wound healing outcomes. By utilizing recent advances in protein-conjugation chemistry, interfacial science, and nano-submicron fabrication technologies, I propose to fundamentally change the corneal wound to promote healing. Compared to conventional topical treatment of a corneal wound with therapeutic agents, the direct integration of cytoactive factors into the corneal wound bed enables the use of significantly less compound, an approach that provides a much lower likelihood of cytotoxicity, has a much greater safety margin, and presents significant cost savings in the execution of the therapeutic plan. Biodegradable materials will be used to gain temporal control over cytoactive factor persistence in the corneal wound. Direct integration of cytoactive factor(s) into the corneal wound will minimize the probability of deleterious effects resulting from long-standing, persistent cytoactive factor signaling. Antimicrobial factors such as silver and human b-defensin-3, a naturally occurring host peptide, will be used to test the novel proposition that their direct integration into the corneal wound can provide antimicrobial activity without impairing healing. The overall purpose of this proposal is to determine how novel approaches to interfacial materials engineering can be utilized to fundamentally alter the surface chemistry and biophysical characteristics of the corneal wound bed to promote favorable healing outcomes. In hypothesis 1, polyelectrolyte multilayers (PEMs) loaded with nano-submicron beads will be utilized to integrate antimicrobial compounds and cytoactive factors into the corneal wound bed. Exciting preliminary data already have documented the feasibility of transferring functionalized PEMs into wound beds by stamping and shown that submicron beads within the PEMs are required for efficient transfer to soft materials such as corneal wound beds. By optimizing the biodegradation of PEMs and bead materials, transient residence of antimicrobial and cytoactive factors integrated into the corneal wound bed can be achieved. The kinetics, antimicrobial activity, and cytotoxicity of silver and b-defensin-3 will then be investigated following incorporation into beads and/or PEMs. In hypothesis 2, protein linkage chemistries will directly integrate antimicrobial compounds and cytoactive factors into the corneal wound bed. Recent studies have demonstrated the ability to covalently immobilize cytoactive factors on various model surfaces while preserving their bioactivity. First, the safety of various protein linkage chemistries for use with corneal cells will be determined. Then, the optimal linkage chemistry to enable tuning or transient residence of a cytoactive factor, EGF, will be determined as well as the best process for immobilizing EGF to the corneal wound bed. Lastly, the efficacy of covalently immobilized EGF will be compared to traditional topical treatment of EGF. If successful, the outcomes of this grant will have a dramatic impact on the management of corneal wounds in humans and animals.
Corneal trauma and infection are common and responsible for 6 to 8 million cases of blindness worldwide. Poor corneal wound healing can result in permanent loss of corneal transparency, and there are limited medical and surgical treatments available to address this problem. The purpose of this proposal is to develop novel treatments to aid in corneal wound healing using an engineering-inspired approach; these new therapies may profoundly alter how we treat corneal wounds in people and animals.
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