Modeling Neural Progenitor Cell Dysfunction and Neurogenesis in a Stem Cell-Based Assay Model of Multiple Sclerosis

Background: To model the initial interactions of immune cells with Neural stem cells (NSC) in multiple sclerosis (MS).

Objectives: Despite discoveries of susceptibility genes and immunomodulatory medications for MS, we struggle to understand and treat MS progression. We found that inflammation targets neural progenitors, altering their regenerative capacity in MS models in vivo. Recently, elegant cell culture techniques to study remyelination have been proposed, however the mechanisms of dysfunction of  (NSCs) and neurons in MS are still unknown. It has been suggested by a number of labs, including our work that chronic activation of microglia and astrocytes leads to a non-permissive environment. However the direct role of  of T cells on NSCs function and neurogenesis is unknown. Our laboratory is focused on developing novel stem cell platforms to model neurodegeneration and repair in MS, with the goal to find therapies in progressive MS.

Methods: We investigated the interactions of T cells and their effects on migration, differentiation of NSCs. NSCs were cultured with addition of activated T cells differentiated in vitro into encephalitogenic Th1 or Th2 cells. Cocultures of T cells activated with antigen and controls are used to establish the effects of T cells on NSCs. The co-cultures were allowed to differentiate for 2 weeks harvested and fixed for immunohistochemistry. NSC with naïve T cells or no T cells will be used as controls. To avoid false identification of nuclei, we used confocal microscopy and Z-stack 3D reconstructions. Neural progenitor cells were examined for Pax6 and Dcx staining (neuronal progenitors). We used live microscopy to study the effects of T cells on migration of NSCs carrying GFP transgene.

Results: We show we show that activated Th1 vs. Th2 cells exert differential effects on NSC in 2D cultures. Th1 cells leads to dormancy of NSCs with decrease in proliferation, however when these NSCs were replated with FGF they formed colonies that were able to differentiate into neurons and glia.  Remarkably, Th2 cells augment Pax6+ radial glial progenitors and radial migration of DCX neural progenitor into radial glia, that is critical for neurogenesis and  neocortex formation and  increases neurogenesis into Map2b+ neurons. In addition, Th2 co-cultures change the morphology and GFAP expression of astrocytes to a radial glia morphology.

Conclusions: Our stem cell platform combining  stem cell techniques and neuroimmunology would help to understand the initial pathological/reparative events of NSCs by T cells. This model would help to screen FDA approved-drugs that could target the inflammation-induced degeneration in stem cell based assays.