Project Summary/Abstract This four-year proposal for the K08 Mentored Clinical Scientist Career Development Award aims to further the professional skills of the candidate Daniel E. Maidana, MD, PhD while addressing critical scientific inquiries related to the contribution of mononuclear phagocytes to photoreceptor (PR) cell death in retinal detachment (RD). The candidate's proposed career and scientific goals rely on the protected research time necessary to master advanced laboratory methods and develop leadership skills under the guidance of an expert multidisciplinary mentoring team. This collaborative work, which builds on prior research and established mentoring relationships, will provide the basis for a successful and productive transition to independence. The career advancement plan for the candidate, currently an Assistant Professor of Ophthalmology at the University of Illinois at Chicago (UIC), will consist of i) graduate-level courses in immunology, biostatistics, transcriptomics, and bioinformatics, at UIC; ii) advanced laboratory technical and analytical methods, guided by an expert Mentoring and Advisory Committee; iii) development of management and mentoring skills required to lead a productive, independent laboratory. The institutional environment, departmental support, and cross- disciplinary mentorship team will enable the candidate to maximize productivity during these four years. The Department of Ophthalmology and Visual Sciences at UIC has a consistent record in transitioning early physician-scientists to established independent investigators and strongly supports the candidate for this award. The scientific goal of this proposal is to define the independent contribution of retinal microglia (MG) and blood- derived monocytes/macrophages (Mø) to PR demise and vision loss in an experimental model of RD. Since MG and Mø can either contribute to or resolve the initial injury, several therapeutic approaches have been recently proposed to modulate these cells. However, recent work has unveiled technical limitations and a lack of specificity in the methods used to ablate MG and Mø, thus limiting our understanding of their independent role in promoting or reducing PR cell death. This goal will be accomplished using a novel inducible conditional deletion model to i) define the role of MG in dead PR clearance in early RD; ii) dissect the contribution of MG and Mø phenotypes to promote PR demise in late RD; and iii) determine the neuroprotective potential of MG and Mø to rescue PR cell death following RD. The successful completion of this proposal will generate technical and scientific advancements in our understanding of MG and Mø. We expect this work to provide mechanistic insights to develop effective neuroprotective therapies, allowing us to maximize visual outcomes in the detached retina to prevent vision loss.