Human induced pluripotent stem cells (hIPSCs) could enable a paradigm shift in personalized medicine. However, a roadblock in advancing hIPSC-derived therapeutic cells to the clinic is that hIPSCs generated by current approaches are genetically unstable and, therefore, carry an elevated risk of cancer. What causes genomic instability in hIPSCs remains unknown. We propose a new mechanism to explain why hIPSCs demonstrate genomic instability and we present a simple, generally applicable and cost-effective method to prevent this deleterious process. The rationale for this project is based on our recent finding that hIPSCs have reduced levels of deoxyribonucleotide triphosphate (dNTP) precursors of DNA. The inability of cultured hIPSCs to produce sufficient dNTPs through a metabolic circuit known as the de novo pathway (DNP) triggers DNA replication stress, which is a well-established cause of genomic instability. To prevent the dNTP shortage and its consequences, we propose that, in addition to the DNP, a second dNTP biosynthetic mechanism known as the nucleoside salvage pathway (NSP) must be operational during hIPSC culture. We further propose that supplementing the hIPSC culture medium with deoxyribonucleoside substrates of the NSP will increase dNTP pools and significantly reduce genomic instability. If successful, the new hIPSC culture methods proposed here could be rapidly adopted in the field, with important consequences for the therapeutic potential of hIPSC-derivatives.
Statement of Benefit to California:
Human induced pluripotent stem cells (hIPSCs) may enable the development of autologous cell replacement therapies for many diseases that significantly impact human health in California. However, the genomic instability of hIPSCs obtained using current procedures has been linked with an increased risk of cancer, and therefore is a major challenge in the development of hIPSC-based therapies that can advance to the clinic. The technology we propose to develop utilizes optimization of the cell culture conditions, which should significantly increase the genomic stability of hIPSCs and their derivatives. Establishing the means to maintain genetically stable hIPSCs will be instrumental in unlocking the therapeutic promise of personalized pluripotent stem cell-based therapeutics. This research should also lead to economic benefits in California by creating new cell culture reagents, protocols and technologies with vast commercial potential.