Preventing Pluripotent Cell Teratoma in Regenerative Medicine Applied to Hematology Disorders

Abstract

Iatrogenic tumorigenesis is a major limitation for the use of human induced pluripotent stem cells (hiPSCs) in hematology. The teratoma risk comes from the persistence of hiPSCs in differentiated cell populations. Our goal was to evaluate the best system to purge residual hiPSCs before graft without compromising hematopoietic repopulation capability. Teratoma risk after systemic injection of hiPSCs expressing the reporter gene luciferase was assessed for the first time. Teratoma formation in immune‐deficient mice was tracked by in vivo bioimaging. We observed that systemic injection of hiPSCs produced multisite teratoma as soon as 5 weeks after injection. To eliminate hiPSCs before grafting, we tested the embryonic‐specific expression of suicide genes under the control of the pmiR‐302/367 promoter. This promoter was highly active in hiPSCs but not in differentiated cells. The gene/prodrug inducible Caspase‐9 (iCaspase‐9)/AP20187 was more efficient and rapid than thymidine kinase/ganciclovir, fully specific, and without bystander effect. We observed that iCaspase‐9‐expressing hiPSCs died in a dose‐dependent manner with AP20187, without reaching full eradication in vitro. Unexpectedly, nonspecific toxicity of AP20187 on iCaspase‐9‐negative hiPSCs and on CD34+ cells was evidenced in vitro. This toxic effect strongly impaired CD34+‐derived human hematopoiesis in adoptive transfers. Survivin inhibition is an alternative to the suicide gene approach because hiPSCs fully rely on survivin for survival. Survivin inhibitor YM155 was more efficient than AP20187/iCaspase‐9 for killing hiPSCs, without toxicity on CD34+ cells, in vitro and in adoptive transfers. hiPSC purge by survivin inhibitor fully eradicated teratoma formation in immune‐deficient mice. This will be useful to improve the safety management for hiPSC‐based medicine. Stem Cells Translational Medicine 2017;6:382–393

Scarless Enriched selection of Genome edited Human Pluripotent Stem Cells Using Induced Drug Resistance

“…By correlating the hPSC scores with the sensitivities of each cell line to each of 543 compounds, we identified YM155 as the most effective drug in cells with high hPSC scores (Fig. 1B); this implies that YM155 should be highly specific for hPSCs, as demonstrated previously (Bedel et al, 2017; Kang et al, 2017; Kim et al, 2017; Lee et al, 2013b). Based on correlation of drug and gene expression signature (Fig.…”

“…To address this danger, several approaches have been developed for selective removal of residual hPSCs (Jeong and Cha, 2017). For example, we previously reported that YM155, a survivin inhibitor developed as an anti-cancer drug, is selectively cytotoxic against undifferentiated hPSCs and inhibits teratoma formation (Lee et al, 2013b), and this finding has been reproduced in several independent studies (Bedel et al, 2017; Kang et al, 2017; Kim et al, 2017). At that time, however, the molecular mechanism underlying the high susceptibility of hPSCs to YM155 had not been fully elucidated.…”

“…Selective induction of cell death in hPSCs by YM155, which decreases teratoma formation (Bedel et al, 2017; Kang et al, 2017; Kim et al, 2017; Lee et al, 2013b), is associated with the DNA damage response (Lee et al, 2013b). Cytotoxicity of YM155 cannot be fully prevented by suppression of BIRC5 (which encodes survivin) (Sim et al, 2017).…”

Human Genomic Safe Harbors and the Suicide Gene-Based Safeguard System for iPSC-Based Cell Therapy

“…Another suicide gene system, such as iCaspase-9/AP20187, could be more promising as a safeguard for tumorigenesis © 2019 The Authors. STEM CELLS TRANSLATIONAL MEDICINE published by Wiley Periodicals, Inc. on behalf of AlphaMed Press STEM CELLS TRANSLATIONAL MEDICINE after transplantation [49,50]. However, this system may not be available in hematopoietic stem cell engraftment as nonspecific toxicity of AP20187 on hiPSCs and CD34 + cells have been reported [49].…”

The Nexus of Stem Cell-Derived Beta-Cells and Genome Engineering

“…It is widely thought that the more differentiated a cell population the lower the [16][17][18]. Antibody-based negative selection methods [14,15] and chemical ablation methods [16,19,20] have been devised to reduce tumorigenicity by removing undifferentiated cells from immature cell populations. However, these methods are cumbersome as they generally rely on multiple steps and potential off target effects, and it is not clear whether these approaches are applicable in vivo for removing cells in a patient.…”