The authors report LD-b-PBTA, a lipid droplet–selective, highly retained fluorescent probe that enables long-term (up to 72 h) labeling and in vivo/ex vivo detection of pathological lipid droplet accumulation in dopaminergic neurons in Parkinson's disease models.

This tool enables longitudinal, in vivo visualization of a metabolic/pathology biomarker (lipid droplets) in the substantia nigra, facilitating biomarker development, mechanistic study of lipid-related PD pathology, and screening of interventions that target lipid metabolism or downstream…

Lipid droplets are highly dynamic organelles in nerve cells and are essential for the function of the central nervous system. The abnormal accumulation of lipid droplets in dopaminergic neurons, found in Parkinson's disease (PD) cells and animal models, presents as a promising target for PD diagnosis. However, previously reported fluorescent probes are unsuitable for in vivo long-term tracking of lipid droplets, limiting their applications in animal models of PD. Here, we developed three lipid droplet-targeted probes, named s-CBTA, b-CBTA, and LD-b-PBTA, which share similar chemical structures but exhibit distinct staining properties in cells. Both s-CBTA and b-CBTA stained lipid droplets as well as other membrane structures, but the majority of these molecules were largely excluded by live cells within 24 h. In contrast, LD-b-PBTA exclusively targeted lipid droplets and was retained well in live cells for 72 h. LD-b-PBTA was successfully used for long-term monitoring of the abnormal accumulation of lipid droplets in cultured dopaminergic neurons following rotenone treatment. Furthermore, LD-b-PBTA detected lipid droplet accumulation in dopaminergic neurons both in fresh substantia nigra tissue and in fixed tissue sections from PD animal models. Most importantly, abnormal lipid droplet accumulation in the substantia nigra of living PD animals was successfully revealed using LD-b-PBTA. Together, these results suggest that the LD-b-PBTA probe has great potential for application in the clinical diagnosis of PD.