Abstract
Reprogramming diseased cells with mutated genes into induced pluripotent stem cells (iPSCs) can allow studies of disease mechanism and correct the mutation. Oculofaciocardiodental (OFCD) syndrome is a developmental disorder caused by heterozygous mutations in the X-linked BCL-6 corepressor (BCOR) gene. In this present study, we aimed to reprogram stem cells from a tooth apical papilla (SCAP) of a patient with OFCD, termed SCAP-O, into iPSCs. The SCAP-O carry a copy of the BCOR gene having 1 nucleotide deletion in 1 of the alleles, therefore harboring a mixture of cells expressing either normal (SCAP-OBCOR-WT) or mutated (SCAP-OBCOR-mut) BCOR transcripts. We subcloned SCAP-O and separated SCAP-OBCOR-WT and SCAP-OBCOR-mut as verified by sequencing. The selected subclone SCAP-OBCOR-mut expressed only the mutated BCOR transcripts and remained in such condition after multiple passages. We reprogrammed SCAP-O and subclone SCAP-OBCOR-mut into transgene-free iPSCs using an excisable lentiviral vector system (hSTEMCCA-loxP) carrying 4 reprogramming factors in a single cassette, followed by removal of transgenes via Cre-mediated excision. We found that after reprogramming SCAP-O or subclone SCAP-OBCOR-mut into iPSCs, some of the iPSC clones expressed either solely the normal BCOR-WT or BCOR-mut transcripts, while other clones expressed both BCOR-WT and BCOR-mut transcripts. This is our first step toward establishing OFCD study models by generating isogenic control BCOR-WT iPSCs versus BCOR-mut iPSCs.