Multiple sclerosis (MS) is an auto-immune disease characterized by inflammation, demyelination and neural degeneration. While MS etiology is still uncertain, recent studies propose an interplay between genetic and environmental factors but MS genetic determinants are still poorly understood. Recent advances in 3D cerebral organoid cultures, derived from induced pluripotent stem cells (iPSCs), provide new avenues to investigate human disorders. Cerebral organoids contain ventricular structures aligned by neural stem cells, progenitor cells in various stages of differentiation, and neurons in a typical inside-out stratified layout. Furthermore, it has been shown that myelination can be induced in those neurons.
We propose here to use human iPSC derived cerebral organoids to study the genetic components of multiple sclerosis. The lack of blood vessels and immune cells in cerebral organoids allows the study of the effect of MS genetic component on neural cells.
Cerebral organoids were derived from iPS cells of patients with MS. We analyzed stem cell proliferation, migration and differentiation in neuronal and glial lineages in MS organoids compared to healthy control organoids at 42 days in vitro.
MS cerebral organoids seemed to grow faster compared to healthy control organoids, suggesting a higher stem cell proliferation rate. Immunostainings for stem cell marker SOX2 and neuroblast marker DCX revealed that the stem cell pool localized in the Ventricular/Subventricular Zone was larger in MS cerebral organoids compared to control. A lower DCX intensity was detected in MS cerebral organoids, suggesting that MS cerebral organoids might have developed an enlarged stem cell pool at the expense of the neuroblast population. A preliminary quantification of cortical neuron marker CTIP2 did not show a statistically significant difference between MS organoids and healthy controls, suggesting that neuronal maturation might not be affected. An analysis of apoptosis marker CC3 displayed an increase of CC3+ cell numbers in MS organoids, particularly in cortical plate, with little to no cell death in the stem cell pools in both organoid populations. A further analysis of DNA damage and senescence in stem cells as well as oligodendrocyte maturation will be performed.
This study will give new insight on the origin and evolution of the disease and will help to identify potential target for therapeutic strategies designed to promote myelin repair in MS.