Telomere-Associated Proliferative Capacity in Expandable Porcine Hepatocyte-like Progenitor Cells.

Primary hepatocytes are limited by poor proliferative capacity and a finite replicative lifespan, restricting their utility in long-term in vitro studies. Here, we report the generation of expandable hepatocyte-like progenitor cells from GGTA1 knockout pigs, a large-animal model with reduced immunogenicity. Porcine fibroblasts were directly reprogrammed using a non-integrative episomal system encoding hepatic transcription factors, enabling stable lineage conversion without genomic integration. A simplified two-vector configuration combined with codon optimization enabled evaluation of vector-dependent effects while maintaining genomic safety without viral integration. The resulting cells exhibited hepatocyte-like morphology and gene expression, and transcriptomic analysis revealed a progressive shift toward liver-associated profiles during extended culture. Chromosomal analysis revealed vector-dependent differences in genomic stability, with codon-optimized cells showing increased aneuploidy, indicating a trade-off between proliferative capacity and genomic integrity. The cells also demonstrated sustained proliferative capacity, supported by maintenance of telomere length, increased expression of