Researchers have developed the TK4 PiggyBac vector to solve the common problem of transgene silencing during the differentiation of human pluripotent stem cells. While many genetic constructs work in undifferentiated cells, they often lose functionality as those cells become mature neurons or microglia. This study identifies that combining CAG or Ubc promoters with the WPRE regulatory element effectively maintains robust gene expression throughout the maturation process. The team also discovered three novel genomic safe harbor loci that support stable integration without disrupting existing human genes. Independent testing across seven different laboratories and nine distinct protocols confirmed that the TK4 system is a highly reproducible tool for long-term genetic studies. Consequently, this technology provides a reliable framework for CRISPR-based screens and disease modeling in specialized cell types.

References:

• Uenaka T, Napole A, Saha A D, et al. Prevention of transgene silencing during human pluripotent stem cell differentiation[J]. Cell Stem Cell, 2026, 33(3): 517-530. e8.