Rapid generation of ventral spinal cord-like astrocytes from human iPSCs for modeling non-cell autonomous mechanisms of lower motor neuron disease

Astrocytes play important roles in the function and survival of neuronal cells. Dysfunctions of astrocytes are associated with numerous disorders and diseases of the nervous system, including motor neuron diseases such as amyotrophic lateral sclerosis (ALS). Human induced pluripotent stem cell (iPSC)-based approaches are becoming increasingly important for the study of the mechanisms underlying the involvement of astrocytes in non-cell autonomous processes of motor neuron degeneration in ALS. These studies must account for the molecular and functional diversity among astrocytes in different regions of the brain and spinal cord. It is essential that the most pathologically-relevant astrocyte preparations are used when investigating non-cell autonomous mechanisms of either upper or lower motor neuron degeneration in ALS. In this context, the main aim of this study was to establish conditions enabling rapid and robust generation of physiologically-relevant ventral spinal cord-like astrocytes that would provide an enhanced experimental model for the study of lower motor neuron degeneration in ALS. Neural progenitor cells with validated caudal and ventral features were derived from human iPSCs and differentiated into astrocytes, which were then characterized by examining morphology, markers of ventral spinal cord astrocytes, spontaneous and induced calcium transients, and astrogliosis markers. Efficient and streamlined generation of human iPSC-derived astrocytes with molecular and biological properties similar to physiological astrocytes in the ventral spinal cord was achieved. These induced astrocytes express markers of mature ventral spinal cord astrocytes, exhibit spontaneous and ATP-induced calcium transients, and lack signs of overt activation. Human iPSC-derived astrocytes with ventral spinal features offer advantages over more generic astrocyte preparations for the study of both ventral spinal cord astrocyte biology and the involvement of astrocytes in mechanisms of lower motor neuron degeneration in ALS.