Figure 1.

Differentiation protocols for the generation of motor neurons (MNs) from human induced pluripotent stem cells (iPSCs) as used in this study. The protocols by Du et al. [38], Maury et al. [39], and Kroehne et al. [40] were adopted with minor changes. Motor neuron progenitors (pMNs) generated on day 12 with the protocol based on Du et al. [38] can be expanded in a valproic acid (VPA) containing expansion medium for a limited time. The protocol based on Kroehne et al. [40] is divided into the (A) generation and expansion of a pure population of neural progenitor cells (NPCs) and (B) differentiation to MNs. Abbreviations for the supplements can be found in Table A1.