ABSTRACT
Length-dependent axonal degeneration is the pathologic hallmark of several neurodegenerative disorders, including inherited peripheral neuropathies (Charcot-Marie-Tooth (CMT) disease). CMT is currently an untreatable disorder. This is partially due to lack of translational models suitable for drug discovery. In vitro models of CMT have been hindered by the 2D configuration of neuronal cultures, which limits visualization and orientation of axons. To overcome these limitations, we cultured induced pluripotent stem cell (iPSC)-derived spinal motor neurons as 3D spheroids, which grow axons in a centrifugal fashion when plated. Using these iPSC-derived spinal spheroids, we demonstrate neurofilament deposits in motor neuron axons of three patients with CMT2E, caused by mutations in the NEFL gene. This phenotype is partially reversed by two kinase inhibitors. In summary, we developed a human tridimensional in vitro system that models length-dependent axonopathies, recapitulates key pathophysiologic features of CMT2E, and should facilitate the identification of new therapeutic compounds for CMT.
