Comparative analysis of chemical and lentiviral approaches in the generation of human induced pluripotent stem cell–derived motor neurons

The generation of human induced pluripotent stem cell-derived motor neurons overcomes limited access to human tissues and offers an unprecedented approach to modeling motor neuron diseases such as dystonia and amyotrophic lateral sclerosis. Motor neurons generated through different strategies may exhibit substantial differences in purity, maturation, characterization, and even neuronal identity, leading to variable outcomes in disease modeling and drug screening. However, very few comparative studies have been conducted to determine the similarities and differences among motor neurons prepared via different protocols. In this study, we prepared human induced pluripotent stem cell-motor neurons via lentiviral delivery of transcription factors and chemical induction and performed a systematic comparative analysis. We found that motor neurons generated by both approaches showed typical motor neuron morphology and robustly expressed motor neuron-specific markers, such as nuclear homeobox transcription factor 9 and choline acetyltransferase. The chemical induction protocol utilizes a combination of small molecules to induce motor neuron differentiation, offering a significantly faster maturation time of 35 days compared to 46 days with lentiviral delivery of transcription factors. Additionally, while lentiviral delivery of transcription factors are suitable for downstream biochemical analysis, chemical induction are more applicable for therapeutic approaches as they avoid the use of lentiviruses. Both approaches produce motor neurons with high purity (> 95%) and yield. No significant differences were found between chemical induction and lentiviral delivery of transcription factors in terms of motor neuron markers and maturation markers. These robust methodologies offer researchers powerful tools for investigating motor neuron diseases and potential therapeutic strategies.