IDENTIFICATION OF PROLIFERATING NEURAL PROGENITORS IN THE ADULT HUMAN HIPPOCAMPUS

Neurogenesis in mammals occurs primarily in the dentate gyrus of the hippocampus and the subventricular zone of the lateral ventricles. While hippocampal neurogenesis supports plasticity, memory and mood regulation, its persistence in adult humans remains debated because proliferating progenitors are rare and difficult to detect. To address this, we performed large-scale single-nucleus RNA sequencing (snRNA-seq) on human hippocampi spanning from birth to old age, combined with machine-learning analysis and multi-modal validation. Transcriptomic profiling revealed a continuous neurogenic trajectory from neural stem cells through intermediate progenitors to neuroblasts that is detectable across the lifespan, all canonical progenitor stages having been resolved in early childhood. In adult hippocampi, to boost sensitivity for rare, actively dividing neural progenitors, we enriched libraries for nuclei positive for the proliferation marker Ki-67 by fluorescence-activated sorting.
We then trained supervised machine-learning classifiers on the transcriptomic signatures of clearly annotated progenitor stages from early childhood and applied these classifiers to adult hippocampal data to detect nuclei transcriptionally similar to neural stem cells, intermediate progenitors and neuroblasts.
Spatial validation with RNAscope and Xenium confirmed marker expression and localization of these progenitors within the adult dentate gyrus. Collectively, these molecular and spatial data provide evidence consistent with persistent, continuous neurogenesis in the adult human hippocampus, refine the cellular map of the dentate gyrus, and have implications for mechanisms of neural plasticity and for neurological and psychiatric disease.