Transcriptional Heterogeneity Reveals a Synaptic Gene Program in Developing and Adult Human Oligodendrocyte Precursor...

Area of Science:

• Neuroscience
• Developmental Biology
• Cell Biology

Background:

• Human oligodendrocyte precursor cells (OPCs) are crucial for brain development, but their heterogeneity is not well understood.
• Early gestation involves OPC proliferation in the human cortex, yet specific functional subtypes remain largely undefined.

Purpose of the Study:

• To investigate the heterogeneity of human embryonic OPCs.
• To identify and characterize novel OPC subsets in the developing human cortex.
• To explore the potential role of OPCs in early neuron-glia communication.

Main Methods:

• Isolation and single-cell RNA sequencing of over 2,300 human embryonic OPCs from post-conceptional week 17 cortex.
• Unsupervised clustering to identify distinct OPC transcriptional subsets.
• Histological analyses and spatial transcriptomics to determine eSyn-OPC localization and timing.
• In vitro differentiation assays to confirm lineage identity.
• Reanalysis of adult human single-nucleus RNA-seq data.

Main Results:

• Four transcriptionally distinct embryonic OPC subsets were identified, including a novel population termed embryonic synaptic OPCs (eSyn-OPCs).
• eSyn-OPCs comprised ~28.5% of embryonic OPCs and expressed genes related to synaptic development, signaling, and neuromodulation.
• eSyn-OPCs were found in proliferative germinal zones from PCW 15 onwards, suggesting early involvement in cortical assembly.
• A transcriptionally analogous subset, adult synaptic OPCs (aSyn-OPCs), was identified in adult brains, albeit with reduced synaptic gene expression.

Conclusions:

• Human embryonic OPCs exhibit significant heterogeneity, with a distinct eSyn-OPC subset possessing rich synaptic machinery.
• eSyn-OPCs appear to be involved in early cortical development and may directly participate in neuron-glia communication.
• The discovery of synaptically specialized OPCs suggests novel roles in shaping neural circuit formation during development and in adulthood.