Endogenous neural precursor cells in health and disease.

Neurogenesis persists in the adult brain of mammals in the subventricular zone (SVZ) of the lateral ventricles and in the subgranular zone (SGZ) of the dentate gyrus (DG). The complex interactions between intrinsic and extrinsic signals provided by cells in the niche but also from distant sources regulate the fate of neural stem/progenitor cells (NPCs) in these sites. This fine regulation is perturbed in aging and in pathological conditions leading to a different NPC behavior, tailored to the specific physio-pathological features. Indeed, NPCs exert in physiological and pathological conditions important neurogenic and non-neurogenic regulatory functions and participate in maintaining and protecting brain tissue homeostasis. In this review, we discuss intrinsic and extrinsic signals that regulate NPC activation and NPC functional role in various homeostatic and non-homeostatic conditions.

Commonalities in immune modulation between mesenchymal stem cells (MSCs) and neural stem/precursor cells (NPCs).

Owing to their unique immunomodulatory properties, mesenchymal stem cells (MSCs) have been advocated as a potential therapy for numerous pathological conditions in which immune-mediated inflammatory reactions play a crucial role, such as autoimmune disorders, cerebrovascular diseases and tumours. Increasing evidence suggest that stem cells, other than MSCs, are also capable of immunomodulation. Neural stem/precursor cells (NPCs) have been among the first stem cells to show immunomodulatory properties and nowadays represent one the most studied and promising stem cell subtype in still uncurable acute and chronic inflammatory neurological disorders. Although the ontogeny of NPCs and MSCs greatly diverges, their immunomodulatory mechanisms are similar and are largely based on the bystander (paracrine) effect through membrane-bound and soluble mediators that influence the behavior of host immune cells. This observation suggests the existence of a core stem cell signature across different stem cell lineages and that shared signalling pathways between the stem cell niche and the inflammatory immune response likely mediate both NPC and MSC immunomodulatory effect.