Targeted biallelic integration of an inducible Caspase 9 suicide gene in iPSCs for safer therapies

authored by: Stephanie Wunderlich, Alexandra Haase, Sylvia Merkert, Kirsten Jahn, Maximillian Deest, Helge Frieling, Silke Glage, Wilhelm Korte, Andreas Martens, Andreas Kirschning, Andre Zeug, Evgeni Ponimaskin, Gudrun Göhring, Mania Ackermann, Nico Lachmann, Thomas Moritz, Robert Zweigerdt, Ulrich Martin
Abstract: Drug-inducible suicide systems may help to minimize risks of human induced pluripotent stem cell (hiPSC) therapies. Recent research challenged the usefulness of such systems since rare drug-resistant subclones were observed. We have introduced a drug-inducible Caspase 9 suicide system (iCASP9) into the AAVS1 safe-harbor locus of hiPSCs. In these cells, apoptosis could be efficiently induced in vitro. After transplantation into mice, drug treatment generally led to rapid elimination of teratomas, but single animals subsequently formed tumor tissue from monoallelic iCASP9 hiPSCs. Very rare drug-resistant subclones of monoallelic iCASP9 hiPSCs appeared in vitro with frequencies of ∼ 3 × 10^-8. Besides transgene elimination, presumably via loss of heterozygosity (LoH), silencing via aberrant promoter methylation was identified as a major underlying mechanism. In contrast to monoallelic iCASP9 hiPSCs, no escapees from biallelic iCASP9 cells were observed after treatment of up to 0.8 billion hiPSCs. The highly increased safety level provided by biallelic integration of the iCASP9 system may substantially contribute to the safety level of iPSC-based therapies.
Organisation(s): Institute of Organic Chemistry
External Organisation(s): Hannover Medical School (MHH)
Type: Article
Journal: Molecular Therapy - Methods and Clinical Development
Volume: 26
Pages: 84-94
No. of pages: 11
ISSN: 2329-0501
Publication date: 08.09.2022
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Molecular Medicine, Molecular Biology, Genetics
Sustainable Development Goals: SDG 3 - Good Health and Well-being
Electronic version(s): https://doi.org/10.1016/j.omtm.2022.05.011 (Access: Open)