Changes in neural progenitor lineage composition during astrocytic differentiation of human iPSCs

The regional specificity of stem cell-derived astrocytes is believed to be an important prerequisite for their application in disease modelling and cell-based therapies. Due to the lack of subtype-defining markers for astrocytes in different regions of the brain, the regional identity of in vitro-derived astrocytes is often declared by the dominant positional characteristics of their antecedent neural progenitors, patterned to a fate of interest, with the assumption that the positional trait is preserved by the derived astrocytes via linear descent. Using a human induced pluripotent stem cell line designed for tracing derivatives of LMX1A⁺ cells combined with a ventral midbrain induction paradigm, we show that astrocytes originating from LMX1A⁺ progenitors can only be generated if these progenitors are purified prior to the astrocyte differentiation process, or their progenies are gradually lost to progenies of LMX1A^- progenitors. This finding indicates that the lineage composition of iPSC-derived astrocytes may not accurately recapitulate the founder progenitor population. Using deep single-cell RNA sequencing, we identified distinct transcriptomic signatures in astrocytes derived from the LMX1A⁺ progenitor cells. Our study highlights the need for rigorous characterization of pluripotent stem cell-derived regional astrocytes and provides a resource for assessing LMX1A⁺ ventral midbrain progenitor-derived human astrocytes.