Kidney dysfunction in LVAD recipients is common and harmful. Precise mechanistic characterization of kidney health states in LVAD recipients is important to improving prognostication and outcomes. Current assessments provide limited and confounded information about kidney parenchymal health before or after LVAD implantation. Urine exosomes may offer a non-invasive window into kidney health. We performed an exploratory study assessing kidney health in LVAD recipients using urine exosome isolation and protein biomarkers. Urine was collected and exosomes were isolated from 16 patients received LVAD (HeartMate III) from 1/2022-9/2022, immediately pre-implantation and on post operative day 7. Protein markers (AQP1, NGAL, NHE3, ATF3, and fetuin A) previously found to be associated with kidney health, were studied on urine exosomes. Relationships of exosome protein levels and important baseline clinical characteristics (presence of kidney dysfunction, defined as eGFR<60 ml/min/1.73m2, and hemodynamic instability, defined as INTERMACS 1 or 2) were assessed. Biomarker levels were normalized, and median levels were used for group comparisons. For the 16 LVAD recipients (median age 61 yrs., 81% male), 8 had baseline eGFR below 60, and 8 were INTERMACS 1 or 2. Persons with baseline low kidney function had higher levels of NHE3, Fetuin A, and NGAL (fig.1A). Persons with hemodynamic instability had higher levels of AQP1, Fetuin A, and ATF3 (fig.1B). In comparing biomarker changes with changes in creatinine level (from pre-op to POD 7), NGAL had the highest correlation (Spearman's ρ=0.84, p<0.001, Fig.1C). This pilot study is the first to study urine exosomes in LVAD recipients. The results showed biomarker level changes that are generally in accordance with prior studies assessing urine exosomes in other acute and chronic kidney disease situations. Thus, we have demonstrated the feasibility of studying urine exosomes as a non-invasive way to investigate kidney health in LVAD recipients. [ABSTRACT FROM AUTHOR]