Functional characterization of motor neurons derived from human peripheral blood mononuclear iPSC’s

Cell reprogramming technologies now allow creation of induced pluripotential stem cells (iPSC) from mature differentiated adult cells that can be obtained from living persons. Amyotrophic lateral sclerosis (ALS) is a rapidly progressive, fatal degeneration of motor neurons (MN). There are currently no meaningful treatments to prevent MN death in ALS. We reprogrammed a healthy subject’s peripheral blood mononuclear cells to iPSC’s using electroporation of a reprogramming plasmid, neuralized the iPSC’s and differentiated the resulting neural stem cells (NSC) into motor neurons that expressed MN factors HB9 and ISL1. After 4 weeks of MN differentiation, we then maintained these cells under low oxygen (5%) culture for up to 7 weeks and characterized electrophysiological properties by patch clamp recording of live MN expressing GFP under control of a HB9 promoter. We observed no change in passive membrane properties, sodium current density increased with time in culture and action potential firing following current injection increased. iPSC-derived motor neurons developed firing characteristics of mature motor neurons including repetitive firing, spike frequency adaptation and rebound action potentials. Prolonged culture of iPSC/NSC-derived MN’s resulted in electrophysiological maturation, suggesting their potential for use in studying motor neuron disorders. (191 words)