Metformin enhances human oligodendrocyte function by altering metabolism

Metformin rejuvenates adult rat oligodendrocyte progenitor cells (OPCs) allowing more efficient differentiation into oligodendrocytes and improved remyelination of CNS axons and therefore is of interest as a possible therapeutic in demyelinating diseases such as multiple sclerosis (MS). We set out to test whether metformin had a similar effect in human stem cell derived-OPCs. We assessed the suitability of human monoculture, organoid and transplantation into immunodeficient mice (chimera model) culture systems in simulating in vivo adult human oligodendrocytes, finding most close resemblance in the chimera model. Metformin increased myelin proteins and/or sheaths in all models even when human cells had fetal signatures. In the chimera model, metformin led to a marked increase in mitochondrial area both in the human transplanted cells and in the mouse axons with associated increase in transcripts related to mitochondrial function and metabolism. Human oligodendrocytes from MS brain donors treated pre-mortem with metformin also expressed similar transcripts suggesting that metformin’s brain effect is not cell-specific, altering metabolism in both oligodendrocytes and axons leading to more myelin production, in part through mitochondrial changes. This bodes well for ongoing clinical trials testing metformin for neuroprotection.