The human immune system is the body’s best defense against invaders. But even our hardy immune systems can sometimes be outpaced by particularly dangerous bacteria, viruses or other pathogens, or even by cancer.
But what if we could give our immune system a boost when it needs it most? Last week scientists at the Salk Institute for Biological Sciences devised a new method of doing just that.
Reporting in the latest issue of the journal Stem Cells, Dr. Juan Carlos Izpisua Belmonte and his team announce a new method of creating—and then transplanting—white blood cells into laboratory mice. This new and improved method could have significant ramifications for how doctors attack the most relentless disease.
The authors achieved this transformation through the reprogramming of skin cells into white blood cells. This process builds on induced pluripotent stem cell, or iPS cell, technology, in which the introduction of a set of genes can effectively turn one cell type into another.
This Nobel prize-winning approach, while revolutionary, is still a many months’ long process. In this study, the Salk team found a way to shorten the cellular ‘reprogramming’ process from several months to just a few weeks.
“The process is quick and safe in mice,” said Izpisua Belmonte in a news release. “It circumvents long-standing obstacles that have plagued the reprogramming of human cells for therapeutic and regenerative purposes.”
Traditional reprogramming methods change one cell type, such as a skin cell, into a different cell type by first taking them back into a stem cell-like, or ‘pluripotent’ state. But here, the research team didn’t take the cells all the way back to pluripotency. Instead, they simply wiped the cell’s memory—and gave it a new one. As first author Dr. Ignacio Sancho-Martinez explained:
“We tell skin cells to forget what they are and become what we tell them to be—in this case, white blood cells. Only two biological molecules are needed to induce such cellular memory loss and to direct a new cell fate.”
This technique, which they dubbed ‘indirect lineage conversion,’ uses the molecule SOX2 to wipe the skin cell’s memory. They then use another molecule called miRNA 125b to reprogram the cell into a white blood cell.
These newly generated cells appear to engraft far better than cells derived from traditional iPS cell technology, opening the door to therapies that more effectively introduce these immune cells into the human body. As Sanchi-Martinez so eloquently stated:
“It is fair to say that the promise of stem cell transplantation is now closer to realization.”