Three-dimensional (3D) tetra-culture brain on chip platform for organophosphate toxicity screening

Organophosphate-based compounds (OPs) represent a significant threat to warfighters (nerve agents) and civilian populations (pesticides). There is a pressing need to develop in vitro brain models that correlate to the in vivo brain to rapidly study OPs for neurotoxicity. Here we report on a microfluidic-based three-dimensional, four-cell tissue construct consisting of 1) a blood-brain barrier that has dynamic flow and membrane-free culture of the endothelial layer, and 2) an extracellular matrix (ECM)-embedded tissue construct with neuroblastoma, microglia, and astrocytes. We demonstrated this platform's utility by measuring OP effects on barrier integrity, acetylcholinesterase (AChE) inhibition, viability and residual OP concentration with four model OPs. The results show that the OPs penetrate the blood brain barrier (BBB) and rapidly inhibit AChE activity, and that in vitro toxicity was correlated with available in vivo data. This paper demonstrates the potential utility of a membrane-free tetra-cultured brain on chip that can be scaled to high throughput as a cost-effective alternative method to animal testing.