Design, microfabrication and analysis of a microfluidic chamber for the perfusion of brain tissue slices

Successful perfusion and survival of brain slices using a microfabricated fluidic interface chamber is demonstrated. Up to three chambers are fabricated on the same glass substrate using a standard photolithography process. Their base is filled with arrays of micropillars to replace the nylon mesh used in classical interface chambers. These micropillars confine the flow and also uphold slices at the interface between perfusate and oxygen. Enhanced exposure of the neural tissue to oxygen and to the nutritive substances is reached. Computational fluid dynamics and empirical tests are used to study the flow properties of the chambers. The influence of various micropillar arrangements on the flow is as well analyzed. In these flat perfusion chambers, the flow is laminar and remains confined within the chamber even though the side-walls are not higher than the micropillars (400 μm). At comparable flow rate this small volume microfluidic chamber (about 100 μl) has a perfusate exchange rate at least 4 times faster than conventional perfusion chambers, making experiments with dynamic control of the perfusion medium possible. Using a zero-Mg²⁺ model of epileptiform activity, spontaneous single and multi-spike bursts in the CA3 region of a rat hippocampal brain slice have been observed for more than 5 hours. Compatibility of brain slice perfusion chambers with micro- and nanotechnology is expected to open new avenues in neurophysiology research using multifunction perfusion systems with important integrated features (e.g., microfluidic channels for drug delivery, electrode or sensor arrays).