Effects of curcumin nanoformulations on cellular function in Niemann-Pick disease type C astrocytes

Niemann-Pick disease type C1 (NPC disease) is a neurodegenerative multi-lipid lysosomal storage disease caused by mutations in the NPC1 gene presenting with reduced lysosomal Ca 2+ signalling and inhibited late endosome-lysosome transport. Elevating cytosolic Ca 2+ levels in NPC cells has been shown to reduce lysosomal lipid storage. Treating Npc1 -/- mice with the Ca 2+ modulator curcumin led to reduced lipid storage, improved life expectancy and function. These studies led to reported utilisation of curcumin supplements by NPC disease families despite there being no clinical evidence of benefit and a report indicating no benefit of nanoformulated curcumin in Npc1 -/- mice. The aim of this study was to determine whether various commercially available curcumin nanoformulations were capable of reproducing the findings obtained with unformulated pharmaceutical grade curcumin. We compared seven curcumin nanoformulations in Npc1 -/- mouse astrocytes. All the nanoformulations elevate cytosolic Ca 2+ levels but only two lowered lysosomal lipid storage. Importantly, some caused elevations in NPC lysosomal storage and/or decreased cellular viability. Although this is an in vitro study, our findings suggest that care should be taken when contemplating the use of curcumin supplements for NPC disease.