Optimized protocols for isolation of primary motor neurons, astrocytes and microglia from embryonic mouse spinal cord

Neuron-glial interactions are important in development of the nervous system and pathogenesis of disease. Primary cell cultures prepared from nervous tissue are often used to study the properties of individual cell types and how they interact with each other. Isolation of pure populations of cells and their culture is challenging, particularly from murine spinal cord. The purpose of this study was to optimize various protocols to achieve efficient, parallel isolation and purification of primary motor neurons, microglia and astrocytes from the same mouse embryonic spinal cord sample. Following dissociation of E12 embryonic spinal cords, motor neurons were isolated at 97% purity by a single step centrifugation of the cell suspension through multiple discontinuous density gradients of NycoPrep. The residual mixed cell pellet was resuspended and cultured for 2 weeks. Mixed cultures were then shaken to release microglia, which were then harvested from the medium and subjected to another round of differential adhesion to achieve 99% purity. The astrocytes remaining in the mixed cultures were culled to 98% purity by treatment with leucine methyl ester and a subsequent vigorous shaking step to remove any remaining microglia and neurons. Furthermore, no cross contamination was observed in the glial cultures. This technique provides a simple, convenient, and reliable method of obtaining highly purified preparations of motor neurons, microglia and astrocytes from embryonic spinal cord for the study of spinal cord cell biology and motor neuron diseases.