Human STAP cells – Troubling Possibilities


Soon after the publication of this paper that adult mouse cells could be reprogrammed into embryonic-like stem cells simply by exposing them to acidic environments or other stresses , Charles Vacanti at Harvard Medical School has reported that he and his colleagues have demonstrated that this procedure works with human cells.

STAP cells or stimulus-triggered acquisition of pluripotency cells were derived by Vacanti and his Japanese collaborators last year. These new findings show that adult cells can be reprogrammed into embryonic-like stem cells without genetic engineering. However, this technique worked well in mouse cells, but it was not clear that it would work with human adult cells.

Vacanti and others shocked the world when they published their paper in the journal Nature earlier this year when they announced that adult cells in mice could be reprogrammed through exposure to stresses and proper culture conditions.

Now Vacanti has made good on his promise to test his protocol on human adult cells. In the photo below, provided by Vacanti, human adult cells were reprogrammed to a pluripotent state by exposing them to stresses, followed by growth in culture under specific conditions.

Human STAP cells
Human STAP cells

“If they can do this in human cells, it changes everything, said Robert Lanza of Advanced Cell Technologies in Marlborough, Massachusetts. Such a procedure promises cheaper, faster, and potentially more flexible cells for regenerative medicine, cancer therapy and cell and tissue cloning.

Vacanti and his colleagues say they have taken human fibroblast cells and tested several environmental stressors on them to recreate human STAP cells. He will not presently disclose which particular stressors were applied, he says the resulting cells appear similar in form to the mouse STAP cells. His team is in the process of testing to see just how stem-cell-like these cells are.

According to Vacanti, the human cells took about a week to resemble STAP cells, and formed spherical clusters just like their mouse counterparts. Vacanti and his Harvard colleague Koji Kojima emphasized that these results are only preliminary and further analysis and validation is required.

Bioethical problems potentially emerge with STAP cells despite their obvious potential. The mouse cells that were derived and characterized by Vacanti’s group and his collaborators were capable of making placenta as well as adult cell types. This is different from embryonic stem cells, which can potentially form all adult cell types, but typically do not form placenta. Embryonic stem cells, therefore, are pluripotent, which means that they can form all adult cell types. However, the mouse STAP cells can form all embryonic and adult cell types and are, therefore, totipotent. Mouse STAP cells could form an entirely new mouse. While it is now clear if human STAP cells, if they in fact exist, have this capability, but if they do, they could potentially lead to human cloning.

Sally Cowley, who heads the James Martin Stem Cell Facility at the University of Oxford, said of Vacanti’s present experiments: “Even if these are STAP cells they may not necessarily have the same potential as mouse ones – they may not have the totipotency – which is one of the most interesting features of the mouse cells.”

However the only cells known to be naturally totipotent are in embryos that have only undergone the first couple of cell divisions immediately after fertilization. According to Cowley, any research that utilizes totipotent cells would have to be under very strict regulatory surveillance. “It would actually be ideal if the human cells could be pluripotent and not totipotent – it would make everyone’s life a lot easier,” she opined.

Cowley continued: “However, the whole idea that adult cells are so plastic is incredibly fascinating,” she says. “Using stem cells has been technically incredibly challenging up to now and if this is feasible in human cells it would make working with them cheaper, faster and technically a lot more feasible.”

This is all true, but Robert Lanza from Advanced Cell Technology in Marlborough, Massachusetts, a scientist with whom I have often deeply disagreed, noted: “The word totipotent brings up all kinds of issues,” says Robert Lanza of Advanced Cell Technology in Marlborough, Massachusetts. “If these cells are truly totipotent, and they are reproducible in humans then they can implant in a uterus and have the potential to be turned into a human being. At that point you’re entering into a right-to-life quagmire”

A quagmire indeed, for Vacanti has already talked about using these STAP cells to clone human embryos. Think of it: the creation of very young human beings just for the purpose of ripping them apart and using their cells for research or medicine. Would we allow this if the embryo were older; say the age of a toddler? No we would rightly condemn it as murder, but because the embryo is very young, that somehow counts against it. This is little more than morally grading the embryo according to astrology.

Therefore, whole Vacanti’s experiments are exciting and novel, they hold chilling possibilities. Lanza is right, and it is doubtful that scientists would show the same deference or sensitivities to the moral exigencies he has shown.

Do Stem Cells from Bone Outdo Those from the Heart in Regenerating Cardiac Tissue?


Scientists at Tulane University in New Orleans, La. (US) have completed a study that suggests that stem cells derived from cortical, or compact bone do a better job of regenerating heart tissue than do the heart’s own stem cells.

The study, led by Steven R. Houser, Ph.D., FAHA, director of Tulane’s School of Medicine’s Cardiovascular Research Center (CVRC), could potentially lead to an “off the rack” source of stem cells for regenerating cardiac tissue following a heart attack.

Cortical bone stem cells (CBSCs) are considered some of the most pluripotent cells in the adult body. These cells are naïve and ready to differentiate into just about any cell type. However, even though CBSCs and similar pluripotent stem cells retain the ability to develop into any cell type required by the body, they have the potential to wander off course and land in unintended tissues. Cardiac stem cells, on the other hand, are more likely to stay in their resident tissue.

Bone cross-section

To determine how CBSCs might behave in the heart, Houser’s team, led by Temple graduate student Jason Duran, collected the cells from mouse tibias (shin bones), expanded them in the lab and then injected them into back the mice after they had undergone a heart attack.

The cells triggered the growth of new blood vessels in the injured tissue and six weeks after injection had differentiated into heart muscle cells. While generally smaller than native heart cells, the new cells had the same functional capabilities and overall improved survival and heart function.

Similar improvements were not observed in mice treated with cardiac stem cells, nor did those cells show evidence of differentiation.

“What we did generates as many questions as it does answers,” Dr. Houser said. “Cell therapy attempts to repopulate the heart with new heart cells. But which cells should be used, and when they should be put into the heart are among many unanswered questions.”

The next step will be to test the cells in larger animal models. The current study was published in the Aug. 16 issue of Circulation Research.