Loss of 18q Alters <scp>TGFβ</scp> Signalling Affecting Anteroposterior Neuroectodermal Fate in Human Embryonic Stem Cells

Chromosomal abnormalities acquired during cell culture can compromise the differentiation potential of human pluripotent stem cells (hPSCs). In this work, we identified a diminished differentiation capacity to retinal progenitor cells in human embryonic stem cells (hESCs) with complex karyotypes that had in common the loss of part of chromosome 18q. Time-course gene-expression analysis during spontaneous differentiation and single-cell RNA sequencing found that these variant cell lines poorly specified into anterior neuroectoderm, and, when progressing through differentiation, they yielded poorly pigmented cells, with proliferating and pluripotent cell populations. The variant cell lines showed dysregulation of TGFβ signalling during differentiation, and chemical modulation of the TGFβ pathways showed that the basis of the improper specification was due to imbalances in the anteroposterior neuroectodermal fate commitment.