Stem cell programming has been buzzing the last few years and with recent work suggesting that epigenetic and ncRNA factors are manipulative enough to star in TV drama, we expect the excitement to continue.
But according to a recent report, researchers may need to keep close tabs on how the very methods they use to study epigenetics in stem cells might be introducing changes in the epigenetics of stem cells. Huh?
That’s right, it appears that routine experimental manipulations with stem cells can also have unforeseen consequences of the epigenetic kind. It turns out that just using a lentiviral vectors can tweak the DNA methylation signatures of stem cells.
Researchers in France and Japan say that although they knew that their could be epigenetic changes when manipulating stem cells in vitro, no one knew how this affected common cell and gene therapy protocols. So, they studied a common protocol to see if each of its steps could change the DNA methylation landscape.
They compared untreated human CD34+ cells; cells treated with cytokines; cells treated with cytokines and polybrene (which helps viruses enter the cells); and cells treated with cytokines, polybrene, and a lentiviral vector. Here’s what they found:
- Cytokines induced some subtle changes in two cell-surface markers.
- SIRT1 and DNMT1 levels changed with cytokine addition. SIRT1 levels also changed with vector addition. These results suggested that epigenetic changes were afoot.
- The most striking results came from DNA methylation assays. They showed that cytokines caused methylation/demethylation changes, but these had a balanced net effect. Polybrene slowed down some of these changes, but the lentivirus caused a huge increase in methylation (including in a region containing histone genes).
The team says that the real consequences of these methylation changes are unknown, as virus-transduced cells can still differentiate correctly. But they add that the changes could affect where the viruses insert within the genome, which could have huge safety implications for gene therapies. And it’s something for stem cell researchers to keep in mind when conducting experiments with stem cells too.
Tread carefully and read all the details at PLOS One, November 2012.