Using Skin Cells, Scientists Create Human Motor Neurons in Study

Today is thursday, September 14. I'm Mike Nace, Executive Editor of SMA News today A cocktail of two microRNAs and two transcription factors is enough to transform human skin cells directly into motor neurons, scientists report — an achievement of potentially considerable importance in understanding such motor neuron diseases as spinal muscular atrophy. Damage to motor neurons underlies several devastating and paralyzing diseases, from SMA to ALS. Scientists have struggled to grow human motor neurons in the lab for research purposes, which is one reason this work is so notable. Researchers were able to convert skin cells from healthy adults into motor neurons. Importantly, this process also didn’t require skin cells to change into stem cells before becoming motor nerve cells. In the current study, the research team further investigated the role of these microRNAs and how they help convert skin cells into motor neurons. It found that the microRNAs identified in the study assist cells in holding at a stage where they are ready to convert to neurons. But they were inactive and need more help. After extensive research, researchers identified two transcription factors — ISL1 and LHX3 — were the missing link. Once added to the mix, skin cells turned into spinal cord motor neurons in about 30 days. The four factors — microRNA-9, microRNA-124, ISL1 and LHX3 — help cells shed their skin cell “genetic identity” and embrace instructions that lead them to becoming motor nerve cells, scientists said. The converted motor neurons showed a similar genetic profile — in terms of gene activation and how they work — to mouse motor neurons. How well their genetic profile compares to human motor neurons is still a question, because these cells are very difficult to obtain from living adults. Future studies will let researchers determine how well their converted motor neurons match natural human motor neurons.