A team of researchers from the University of California, San Diego School of Medicine and the Salk Institute for Biological Studies in La Jolla have developed a safe strategy for reprogramming cells to a pluripotent state without use of viral vectors or genomic insertions. Their studies reveal that these induced pluripotent stem cells (iPSCs) are very similar to human embryonic stem cells, yet maintain a "transcriptional signature." In essence, these cells retain some memory of the donor cells they once were.
The study, led by UCSD Stem Cell Program researcher Alysson R. Muotri, assistant professor in the Departments of Pediatrics at UCSD and Rady Children's Hospital and UCSD's Department of Cellular and Molecular Medicine, will be published online in PLoS ONE on September 17.
"Working with neural stem cells, we discovered that a single factor can be used to re-program a human cell into a pluripotent state, one with the ability to differentiate into any type of cell in the body" said Muotri. Traditionally, a combination of four factors was used to create iPSCs, in a technology using viral vectors - viruses with the potential to affect the transcriptional profile of cells, sometimes inducing cell death or tumors.
In addition, while both mouse and human iPSCs have been shown to be similar to embryonic stem cells in terms of cell behavior, gene expression and their potential to differentiate into different types of cells, researchers had not achieved a comprehensive analysis to compare iPSCs and embryonic stem cells.
"One reason is that previous methodologies used to derive iPSCs weren't 'footprint free,'" Muotri explained. "Viruses could integrate into the genome of the cell, possibly affecting or disrupting genes."