Exploring the human oligodendrocyte lineage during development and adulthood through the lens of single-cell methods

Even though much is known about oligodendroglia based on animal models, human oligodendroglia biology knowledge is still lacking. In this thesis, we attempt to characterize human oligodendroglia molecular profiles using single-cell technologies. In papers I and II, we explored human oligodendroglia in the context of development. We identified oligodendrogenesis already occurring as early as 8 postconceptional weeks and revealed the molecular changes in OPC specification with single-cell RNA-seq. We also inspected the epigenetic landscape using single-cell ATAC-seq, revealing which transcription factors are active in OPC specification. Using spatial transcriptomics, we managed to map the OPC to ventral regions, suggesting that the first wave of OPCs also arises from ventral regions as in the mouse. Following the same principles, we investigated the second trimester of gestation in paper II. We characterized the molecular profile of the second-trimester oligodendroglia using single-nuclei RNA-seq and single-nuclei ATAC-seq. We investigated the molecular changes in OPC specification and compared it with the first trimester, showing some overlap, but several unique genes, indicating that in the second trimester OPC specification follows a different pathway. Next, we investigated the human oligodendroglia in adulthood in papers III and IV. Using single-nuclei RNA-seq we characterized the oligodendroglia from different regions-cortex, cerebellum, and spinal cord-and identified unique oligodendroglia populations. We also investigated the changes in oligodendroglia transcriptomic by age and sex. While we observed that aged individuals have reduced expression of genes related to myelination-indicating lower myelination capacity-, sex differences were more subtle. Finally, we investigated the epigenomic landscape of adult human oligodendroglia in paper IV. We used a combination of single-nuclei ATAC-seq and single-nuclei CUT&Tag to investigate the regulatory mechanism in human oligodendroglia. We identified a new candidate SOX10 enhancer in oligodendrocytes and observed the epigenetic priming of the HOX gene family in spinal cord oligodendrocytes. Together, we provided a deep molecular characterization of human oligodendroglia both in development and adulthood.

List of scientific papers

I. Developmental landscape of human forebrain at a single-cell level identifies early waves of oligodendrogenesis. David van Bruggen, Fabio Pohl, Christoffer Mattsson Langseth, Petra Kukanja, Hower Lee, Alejandro Mossi Albiach, Mukund Kabbe, Mandy Meijer, Sten Linnarsson, Markus M. Hilscher, Mats Nilsson, Erik Sundström, Gonçalo Castelo-Branco. Developmental Cell 2022. https://doi.org/10.1016/j.devcel.2022.04.016

II. Specification of oligodendrocyte progenitor cells and their precursors during diferent stages of human neural development. Fabio Pohl, Luise A. Seeker, Mukund Kabbe, Eneritz Agirre, Neemat Mahmud, Carmen Abaurre, David Van Bruggen, Nadine Bestard- Cuche, Zahra Moslehi, Gioele La Manno, Steve Goldman, Anna Williams, Gonçalo Castelo-Branco. [Manuscript]

III. Brain matters: unveiling the distinct contributions of region, age, and sex to glia diversity and CNS function. Luise A. Seeker, Nadine Bestard-Cuche, Sarah Jäkel, Nina-Lydia Kazakou, Sunniva M. K. Bøstrand, Laura J. Wagstaff, Justyna Cholewa-Waclaw, Alastair M. Kilpatrick, David Van Bruggen, Mukund Kabbe, Fabio Baldivia Pohl, Zahra Moslehi, Neil C. Henderson, Catalina A. Vallejos, Gioele La Manno, Goncalo Castelo-Branco, Anna Williams. Acta Neuropathologica Communications 2023. https://doi.org/10.1186/s40478-023-01568-z

IV. Single-nuclei histone modification profiling of the adult human central nervous system unveils epigenetic memory of developmental programs. Mukund Kabbe, Eneritz Agirre, Karl E. Carlström, Fabio Baldivia Pohl, Nicolas Ruffin, David van Bruggen, Mandy Meijer, Luise A. Seeker, Nadine Bestard-Cuche, Alex R. Lederer, Jilin Zhang, Virpi Ahola, Steven A. Goldman, Marek Bartosovic, Maja Jagodic, Anna Williams, Gonçalo Castelo-Branco. BioRxiv 2024. https://doi.org/10.1101/2024.04.15.589512 [Manuscript Preprint]