| Summary: | OBJECTIVES/GOALS: The global incidence of calcific aortic valve disease (CAVD) increased 3.5-fold since 1990. No preventative or therapeutic pharmaceutical therapies exist for CAVD. We will establish the therapeutic potential of osteoclast-derived exosomes though characterization of contents and mechanisms of action to protect against mineralization. METHODS/STUDY POPULATION: Exosomes were purified from conditioned media collected from murine myeloid precursor cells, RAW264.7 (control), and osteoclasts induced to differentiate from RAW264.7 cells (OD). Protein content of exosomes was determined using proteomic analyses. Nucleic acid contents will be identified by sequencing mRNA, miRNA, and DNA. The calcification prevention and reabsorption abilities of control and OD exosomes will be tested using human valvular interstitial cells (VIC) and smooth muscle cell calcification assays and acellular osteologic disc assays, respectively. Comparison between cellular and acellular systems will help identify mechanisms of action, and demonstrate potential therapeutic viability of OD exosomes in preventative vs resorptive treatments. RESULTS/ANTICIPATED RESULTS: OD exosomes, but not control exosomes, prevented calcification in VIC in vitro. OD exosomes contained osteoclast-specific proteins including TRAP, MMP6, cathepsin K, and bone reabsorption factors including V type proton pumps, ATPases, and integrins. These genes are also involved in resorptive activities, and were highly upregulated in OD compared to control exosomes. We anticipate miRNA signatures associated with mineral resorption will also be present. Increased knowledge of exosome cargo will illuminate their mechanism of action and allow future work to engineer increased efficacy. We also anticipate a therapeutic response when OD exosomes are applied after calcification has begun, showing exosomes promote calcium reabsorption. DISCUSSION/SIGNIFICANCE: Establishing therapeutic potential and examining mechanisms of action will pave the way for OD exosomes as a CAVD treatment. Analysis of exosome contents will determine active molecules to be enhanced in future studies. This work will lay a foundation for moving into aortic valve organoid models, which are accepted by the FDA for preclinical trials.
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