Ryan Zenhausern
BME PhD Defense Presentation
Date: 2024-11-07
Time: 9:45am - 11am
Location / Meeting Link: HSRBII N657 / https://emory.zoom.us/j/91745175592
Committee Members:
Dr. James Dahlman Dr. Karmella Haynes Dr. Vivien Sheehan Dr. Hanjoong Jo Dr. Ahmet Coskun
Title: Development of lipid nanoparticles for RNA delivery to hematopoietic stem cells and alternative models in nanoparticle discovery
Abstract:
Lipid nanoparticles (LNPs) have been used to deliver RNA in several FDA approved drugs, including treatments for genetic liver diseases (e.g., ONPATTRO) and as vaccines for COVID-19 (e.g., SPIKEVAX, COMIRNATY). The current LNP discovery pipeline selects for nanoparticles with high liver biodistribution, yet development of next generation RNA therapies that treat diseases outside of the liver will require LNPs that de-target the liver and deliver RNA to other therapeutically relevant cell types. Hematopoietic stem cells (HSCs) represent a clinically attractive target for RNA therapies as dysfunction in this single cell type drives multiple different pathologies including sickle cell disease, ß-thalassemia, anemias, immunodeficiencies, and metabolic disorders. Despite the potential impact RNA therapies can have in the treatment of blood disorders, there are few delivery vehicles that can deliver RNA to these cells. In my work, I sought to identify LNPs that escape the liver and functionally deliver RNA to HSCs. Firstly, I worked to identify lead candidate HSC-LNPs using high-throughput LNP screens at single-cell resolution. Next, I worked to characterize delivery profiles of lead HSC-LNPs across pre-clinical models to investigate the translational potential of identified particles. Next, I identify formulation and post-processing parameters that improve LNP potency and explore biological responses to LNP addition in the bone marrow. Finally, I explored alternative model systems in the nanoparticle discovery pipeline. Current approaches to discovering LNPs for use in human RNA therapies relies on identifying lead candidates in cell culture or animal models and evaluating delivery profiles of these lead candidates across model species which have either underexplored or poorly predictive relationships. Typically, nonhuman primates (NHPs) are used as the final stage animal model to validate LNP-RNA drugs before human trials due to their physiological and immunological similarity to humans. Many initial LNP formulations fail to translate across model systems. Performing initial LNP screens directly in healthy NHPs to circumvent these translational challenges is not feasible due to ethical, practical, and economic concerns. Here, I performed initial LNP screening directly in NHPs with spontaneous disease. Characterizing LNP delivery in these animals is ethically motivated as this adds no additional loss of animal life and has scientific value as this may more closely represent true clinical situations where LNP-RNA drugs are used to treat sick patients.