Purification and culture of corticospinal motor neurons

Corticospinal motor neurons (CSMNs) residing in cortical layer V of the mammalian brain project their axons to the spinal cord, where they connect with spinal motor neurons (SMNs) located in the ventral horn of the spinal cord. CSMNs and SMNs control voluntary movements, and their importance becomes obvious in situations where this network breaks down (i.e., in amyotrophic lateral sclerosis [ALS] and after spinal cord injury). Here we provide an overview of recent progress in the anatomical, morphological, and genetic characterization of developing CSMNs, as well as their survival requirements. We also describe model systems used to study CSMNs and introduce an immunopanning procedure for the purification and culture of CSMNs. Although these procedures have so far been used to purify only rodent CSMNs, in principle they should work to purify CSMNs from any vertebrate species, as well any type of central nervous system (CNS) or peripheral nervous system (PNS) neuron that can be retrograde labeled.