Objective:

This study aims to examine the impact of nanoplastics on microvascular cerebral endothelial cells and neuronal cells, and determine the size at which nanoplastics exhibit the most harmful effects on cells critical to brain health.

Background:

Exposure to micro- and nano-plastics is fundamentally unavoidable as worldwide plastic production continues to grow exponentially. Understanding the impact of plastic on the brain is essential to safeguarding brain health in a modern world. Neurons have the vital function of releasing neurotransmitters to communicate between cells in the brain and to other cells in the body. Cerebrovascular endothelial cells are essential to maintaining the blood-brain barrier by regulating cerebral blood flow, vascular permeability, and neurovascular function. Various physicochemical properties determine a particle’s ability to permeate this barrier, including size and surface charge. 

Design/Methods:

Cultured murine cerebrovascular endothelial cells (bEnd.3) and neuroblastoma cells (N2a) were incubated with polystyrene particles of various sizes and surface charges, and the cell viability was assessed.

Results:

We found that 0.05 µm amine-coated nanoplastics markedly decreased the cell viability of both bEnd.3 and N2a cells, whereas larger particles (2 and 0.1 µm) had no effects on cell viability. The amine-coated nanoplastics produced neuronal cytotoxicity to much greater degree than the carboxylated nanoplastics. The carboxylated nanoplastics did not change the cell viability of the endothelial cells. Fluorescent imaging demonstrated that 0.05 µm nanoplastics were taken up into N2a cells, while larger particles (> 0.1 µm) were present outside of the neurons.

Conclusions:

Our data suggests that both cerebrovascular endothelial cells and neurons are more susceptible to positively charged nanoplastics smaller than 0.1 µm in size compared to negatively charged nanoparticles of the same size. Furthermore, the uptake of the smaller nanoplastic particles into the neurons may play a role in its more pronounced cytotoxic effect.