This week, the stem cell field was shaken by a remarkable discovery that has generated waves across the world. The journal Nature published two studies, a letter and a research article, by Haruko Obokata and collaborators at Charles Vacanti’s lab at Harvard Medical School, that are being heralded as a “medical breakthrough” that could “revolutionize personalized medicine“. The studies report on the controlled reprogramming of differentiated cells into pluripotent cells by simply exposing the cells to an acidic environment.
The authors call this phenomenon stimulus-triggered aquisition of pluripotency (STAP) which, in essence, generates iPS-like cells from any differentiated cell by simply placing the cells in an acid bath for 30 minutes. In the past, a related achievement, that of reprogamming adult cells into induced plutipotent stem cells (iPSC) won Shinya Yamanaka and John Gurdon, the two scientists who came up with the discovery, a Nobel Prize in 2012. Is Obokata’s discovery just as remarkable?
In the Nature study, Obokata showed that three different stresses – membrane pore formation by a bacterial toxin, exposure to acidic pH and physical squeezing – all triggered cells to a pluripotent state. To prove their point, Obokata isolated lymphocytes from mice that were engineered to carry a gene that glows in the presence of Oct-4, a protein found in pluripotent cells. The cells that grew after being exposed to a pH of 5.7 for 30 minutes grew bright green, indicating their pluripotency. After injecting these STAP cells into blastocysts, the cells incorporated into every tissue in the body.
But with the praise came the questions – the most ubiquitous of all being whether this technique will work with real adult cells, since the authors used cells from one week old infant mice. Others are liking the findings to the controversial discovery of very small embryonic-like stem cells (VSEL) 2006, which were recently brought into question by reports that these cells are nothing more than an “aberrant and inactive population” of cell debris and fragments of dying cells. Other opinions verge on calling STAP cells cancer-like, and adding that the stress induced on the STAP cells might remain and manifest itself later.
Whatever the truth, it will hopefully come out as more labs attempt to reproduce Obokata’s results, and in doing so, shed more light on this fascinating new phenomenon.