Characterization of Bergmann Glia-like Progenitors in the Postnatal Mouse Cerebellum by in vivo Electroporation and Spatial Transcriptomics

In the mammalian cerebellum, three types of astroglial cells—Bergmann glial cells (BGs), inner granule cell layer (IGL) astrocytes, and white matter (WM) astrocytes—arise in postnatal timing from two types of progenitors: Bergmann glia-like progenitors (BGLPs) and astrocyte-like progenitors (AsLPs). In contrast to AsLPs, which are commonly observed in other brain regions, BGLPs have not been well studied. Here we investigate their dynamic changes in number, their differentiation abilities and their gene expression profiles during cerebellar development. BGLPs and AsLPs decrease in number as development progresses from P0, and are almost absent by P10. We developed an electroporation-based method to investigate the progeny cells of BGLPs. We found that BGLPs at P6 differentiate into BGs and IGL astrocytes, but not into WM astrocytes, which is consistent with a previous report. However, BGLPs at P0 were observed to differentiate into not only BGs and IGL astrocytes, but also WM astrocytes, indicating that P0 BGLPs possess wider pluripotency than P6 BGLPs. By conducting spatial transcriptomic analysis of the cerebellum at P0 and P6 with over 5,000 probes (Xenium, 5k), we successfully obtained clusters corresponding to BGLPs at P0 and P6, respectively. Further informatics analyses suggested that P0 BGLPs exhibit more stem cell-like features, while P6 BGLPs show a shift toward BG-like characteristics. This study, which includes transcriptome big data, will contribute to understanding the differentiation of BGs and astrocytes, as well as other types of cells, during postnatal cerebellar development.