Characterization of iPSC Lines from PMSE Subjects

Stem cell colonies were maintained at 37°C, 5% CO₂, in mTeSR1 media (Stemcell Technologies, Vancouver, British Columbia, Canada), on tissue culture plates pre-coated with Matrigel (1:100 dilution in DMEM/F12, BD Biosciences, San Jose, California, USA). iPSCs were passaged every 4–7 days using Dispase (Thermo Fisher Scientific, Waltham, Massachusetts, USA). Cultures were confirmed myco-plasma negative via periodic testing with a PCR-based assay. Each line used for experiments had expression of pluripotency markers (NANOG, OCT3/4, SSEA, SOX2) (Dang et al., 2020 (link); Liu et al., 2013 (link); Tidball et al., 2016 (link)). Episomally reprogrammed lines tested negative for episomal reprogramming vector integration. Each line was assessed for chromosomal abnormalities by G-band karyotyping (Cell Line Genetics, Madison, Wisconsin, USA), single nucleotide polymorphism (SNP) chip microarray analysis (Infinium Core Exome-24 BeadChip, Illumina, San Diego, California, USA), or both. Both iPSC lines from the PMSE subjects had a normal karyotype. The SNP chip microarray revealed that the iPSC line from PMSE subject 1 contained a 3.9 Mb gain of genomic material at 3q25.32-q26.1, and the iPSC line from PMSE subject 2 contained a 12 Mb gain of genomic material at 12p13.33-p13.2.