Plasmid-Based Culture Method for Massive Growth of Human Stem Cells

A recent paper described the use of plasmids rather than viral vectors to induce mature blood cells to revert to the primitive state of induced-pluripotent stem cells (iPS), which could then be used for the development of stem cell-based therapies.

Investigators at Johns Hopkins University (Baltimore, MD, USA) had already shown that adult blood cells could be transformed into iPS cells and then from iPS cells into functional heart cells. In the current paper, which was published in the August 8, 2012, online edition of the journal PLoS One, they described a safer and more efficient method for inducing this transformation.

To avoid the possibility that a viral vector could introduce oncogenic genes along with the genes that cause reversion of the adult blood cells, the investigators used plasmids, rings of DNA that replicate briefly inside cells and then degrade. To further stimulate the reversion process the blood cells were cultured with elements from irradiated bone marrow along with other growth factors.

Previous methodology had yielded only a very small percentage of fully functional iPS cells. The technique described in the current study produced an unprecedented 50% to 60% functional iPS cells.

“Taking a cell from an adult and converting it all the way back to the way it was when that person was a six-day-old embryo creates a completely new biology toward our understanding of how cells age and what happens when things go wrong, as in cancer development,” said senior author Dr. Elias Zambidis, assistant professor of oncology and pediatrics at Johns Hopkins University.

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