Towards an in vitro model of biocompatibility testing in the closed eye: tear film neutrophil phenotype and healthy host innate immune responses

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Inflammation is an integral part of the cell response to biomedical devices such as contact lens and stent. Despite many years of research, we have yet to develop materials that are able to interact with the human body without causing complications. To design materials that are compatible with human biological systems, one must first understand how cells interact with materials. Furthermore, appropriate experimental (in vitro) models are needed to test cell response in an environment that appropriately mimics the biological system of study. This is especially true for the eye, with neutrophils, inflammatory white blood cells, invading the front of the eye during prolonged eye closure (1hr or more, and thus every night as we sleep). With their arsenal of inflammatory compounds aimed at fighting off infection and foreign materials, these neutrophils have the potential to significantly damage the ocular surface. However, while hundreds of thousands of live inflammatory cells can be found in the closed-eye, our early results indicate that these neutrophils have a limited ability to respond to inflammatory stimuli. Is the behavior of these cells due to their interactions with other cells, due to the presence of specific tear compounds or are they a different type of neutrophils? This research proposed to fully characterize the response of neutrophils from the closed eye to inflammatory stimuli and bacteria, studying the compounds they release and their ability to eat bacteria. Using a mechanistic in vitro approach, this research aims to gain a better understanding of the cellular mechanisms involved. An in vitro model of the migration process from the blood vessel to the ocular surface will allow to determine how this affects the response of the neutrophils present in the closed eye. Using various cell culture conditions, these migrated neutrophils will then be incubated with different tear proteins and interact with corneal and conjunctival cells. The role that tear proteins, inflammatory compounds and interaction with cells play in protecting the eye from damage and in the neutrophil inflammatory response while we sleep (including in the presence of a biomaterial) will be determined using carefully designed in vitro models. This research program will create new knowledge on mechanisms of inflammation in the ocular environment and how a biomaterial may affect inflammatory response in the closed eye and how to test this in vitro. This will help identify key molecular pathways and enable novel strategies for manufacturers to develop better ocular pharmaceuticals and materials to prevent ocular damage and preserve vision. This program will train four graduate students in interdisciplinary research using methodologies related to cell biology, in vitro model and interaction with materials. The expertise students will gain will allow them to join the rapidly emerging and critically important Canadian biomedical and biotechnology industry.