SignificanceAlzheimer’s disease (AD) is the most common cause of age-related neurodegeneration. Damage initially occurs in the hippocampus, a neurogenic brain region essential in forming memories. Since there is no cure for AD, therapeutic strategies that may aid to slow hippocampal dysfunction are necessary. We describe the precocious hippocampal stem cell loss of a mouse model that mimics the onset of pathological AD-like neurodegeneration. The loss is due to an increase in BMP6 that limits neurogenesis. We demonstrate that blocking BMP signaling by means of Noggin administration is beneficial to the hippocampal microenvironment, restoring stem cell numbers, neurogenesis, and behavior. Our findings support further development of BMP antagonists into translatable molecules for the rescue of stem cells and neurogenesis in neurodegeneration/aging.

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Adult neural stem cells (NSCs) located in the subventricular zone (SVZ) persistently produce new neurons destined to the olfactory bulb (OB). Recent research suggests that the OB is also a source of NSCs that remains largely unexplored. Using single/dual-labeling procedures, we address the existence of NSCs in the innermost layers of the OB. In vivo, these cells are more quiescent that their SVZ counterparts, but after in vitro expansion, they behave similarly. Self-renewal and proliferation assays in co-culture with niche astrocytes indicate that OB-glia restricts NSC activity whereas SVZ-glia has the opposite effect. Gene expression profiling identifies WNT7A as a key SVZ-glial factor lacking in OB-glia that enhances self-renewal, thereby improving the propagation of OB-NSC cultures. These data demonstrate that region-specific glial factors account for in vivo differences in NSC activity and point to WNT7A as a tool that may be instrumental for the NSC expansion phase that precedes grafting.