A functional system for high-content screening of neuromuscular junctions in vitro.

High-content phenotypic screening systems are the logical extension of the current efficient, yet low information content, pre-clinical screens for drug discovery. A physiologically accurate in vitro neuromuscular junction (NMJ) screening system would therefore be of tremendous benefit to the study of peripheral neuropathies as well as for basic and applied neuromuscular research. To date, no fully-defined, selective assay system has been developed which would allow investigators to determine the functional output of cultured muscle fibers (myotubes) when stimulated via the NMJ in real time for both acute and chronic applications. Here we present the development of such a phenotypic screening model, along with evidence of NMJ formation and motoneuron initiated neuromuscular transmission in an automated system. Myotubes assembled on silicon cantilevers allowed for measurement of substrate deflection in response to contraction and provided the basis for monitoring the effect of controlled motoneuron stimulation on the contractile behavior. The effect was blocked by treatment with D-tubocurarine, confirming NMJ functionality in this highly multiplexed assay system.