Introduction: The influence of genetic background on the ability to generate induced pluripotent stem cells\r\n(iPSCs) has the potential to impact future applications, but has yet to be examined in detail. The purpose of this\r\nstudy was to determine if genetic background affects the efficiency of generating iPSCs during early reprograming\r\nas well as the pluripotent stability of the iPSCs during later stages of reprograming.\r\nMethods: Mouse embryonic fibroblasts (MEFs) were isolated from six strains of mice (NON/LtJ; C57BL/6J; DBA/2J;\r\nBALB/cJ; 129S1/SvlmJ; CAST/EiJ) that were selected based on genetic diversity and differences in ability to produce\r\nembryonic stem cell (ESC) lines. MEFs were reprogramed via doxycycline-inducible lentiviral transduction of murine\r\nOct4, Klf4, Sox2, and c-Myc. Differences in efficiency to generate iPSCs were assessed by comparing the total number of\r\ncolonies, the percentage of colonies positive for alkaline phosphatase staining and the percentage of cells positive for\r\nSSEA1. iPSC colonies were expanded to establish doxycycline-independent cell lines whose pluripotency was then\r\nevaluated via ability to form teratomas in NOD.CB17-Prkdcscid/J mice. Proliferation of non-transduced parent MEFs from\r\neach strain was also examined over ten days under conditions that simulated reprograming.\r\nResults: NON/LtJ and CAST/EiJ strains were more efficient than other strains in generating iPSCs for all parameters\r\nmeasured and parent MEFs from these strains were more proliferative than those from other strains. Doxycyclineindependent\r\niPSC lines were established using standard conditions for all strains except BALB/cJ, which required a\r\nhigher concentration (5x) of leukemia inhibitory factor (LIF). iPSCs from all strains were capable of producing\r\nteratomas in NOD.CB17-Prkdcscid/J mice.\r\nConclusions: The results of this study suggest that genetic background does affect iPSC generation and\r\npluripotent stability. In addition, our results demonstrate that strain differences in efficiency to generate iPSCs\r\nduring the early stages of reprograming are correlated with those observed in proliferation of parent MEFs. These\r\nfindings have important implications both for future iPSC applications as well as for future investigation into\r\ndetermining the genes responsible for reprograming efficiency and stability.
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