How (not) to Report a Major Discovery in Stem Cell Science
The genesis of this post comes from a chance viewing of a colleague’s comment on Linkedin, possibly the first time I’ve ever had anything really useful come from that particular social network. Anyway, to get to the point, my colleague posted a link to a BBC news story: “Stem cell ‘major discovery’ claimed” by Health and Science Reporter, James Gallagher. Something about the second sentence set my teeth on edge and made me decide to write this blog:
“Scientists in Japan showed stem cells can now be made quickly just by dipping blood cells into acid.”
I would like to look at this BBC news story and the reporting of the same research by the Guardian “Simple way to make stem cells…” with the aim of making a point about good and bad science reporting.
Both the BBC and the Guardian stories reported the publication of a Nature paper “Stimulus-triggered fate conversion of somatic cells into pluripotency” by Haruko Obokata and her colleagues who are based at a number of different sites in the US and Japan. The paper may be relatively difficult to understand for someone not immersed in the world of stem cell biology research, a field I have barely dipped my toe into. However, there was something that didn’t entirely ring true about the idea that stem cells, the basis of the entire field of regenerative medicine, could be made by “dipping blood cells into acid”! Firstly I suspect most readers would think of red blood cells, which could never be turned into stem cells as in mammals they contain no nuclear DNA, the genetic information that would be required in any stem cell. Secondly, dipping them into acid sounds like it would destroy them rather than turning them back into the kind of cells that can form any part of the body. The Guardian’s reporting of the basic result was a little more nuanced:
“In a series of elegant experiments, researchers showed that cells plucked from animals could be turned into all-powerful master cells simply by immersing them in a mildly acidic solution for half an hour.”
So what was the actual process, and what cells were used? Well, rather than “blood cells”, the researchers actually extracted a number of different cells known as lymphocytes from the spleens of 1 week old mice. Lymphocytes form part of the immune system and come in a variety of different forms, some of which are commonly described as “white blood cells”. This makes me suspect the BBC correspondent didn’t read much past the abstract of the paper or possibly the news report on the Nature website. That source is probably also where he got the idea that the cells were being dipped in acid, whereas in the paper the stimulus is only described as a “low-pH” environment. In actual fact they found that the best effect came from a cell culture medium with a pH of 5.4 to 5.8. While this is more acidic than environments typically found in the body, where normal blood is about pH 7.4, it’s very far away from lemon juice (pH 2), and less acidic than a typical tomato (pH 4.5)*.
The BBC report also missed some of the really remarkable and interesting results of the research, which were reported by Ian Sample in the Guardian. The reprogrammed cells were detected using a standard genetic test that caused them to glow green under fluorescent light if they expressed markers for pluripotency, indicating a possible ability to form other cell types. The researchers went much further than this and showed in a variety of different ways that these new cells were pluripotent, the most convincing of these was the ability to contribute to whole new animals, with the same genetic markers, which could then successfully breed to produce healthy offspring. The Guardian story leads with a short movie showing a glowing green mouse embryo with a beating heart.
While I strongly suspect that the BBC reporter read and understood even less of the original research than I did, does this really matter if they bring the story to a wider audience? Maybe not, but the report in the Guardian demonstrated that it is possible to report this sort of story without resorting to potentially confusing simplifications. It would also be nice to find reports where the journalist has done more than simply reading the press release, as these are often equally guilty of obfuscation while trying to simplify the science.
So what might this lead to? If it can be repeated with mature human cells to create what they call STAP (stimulus-triggered acquisition of pluripotency) cells, this would represent an entirely new way to generate supplies of stem cells for research and ultimately for all kinds of regenerative cell therapies. The controversy over the application of embryonic stem cells in research may have held back this exciting field, and so methods that avoid their use would be welcomed by many.
What the BBC report also missed from the Nature news report was that there were actually two papers from these researchers in the same journal issue. While the first showed that the STAP cells could be processed to generate “STAP stem cells” with properties similar to embryonic stem cells, the second paper demonstrated that they could be altered in a different way to create “trophoblast-like stem cells”. In a natural embryo trophoblast cells form the outer shell and ultimately develop into the placenta. This finding could potentially lead to cloning without the requirement to use a donor egg with the original genetic material removed. However, all of this is a long way off and may well raise other ethical questions.
I would like to acknowledge the assistance of Dr. David Hay of the MRC Centre for Regenerative Medicine in preparing and inspiring this article. You can find out more about his research here.
ps. Less than a week after I first saw this story and decided to write this blog I received the first email from a manufacturer of cell culture chemicals offering a (probably incredibly expensive) culture media formulation specifically designed to help with growing STAP stem cells. There are no flies on these guys!
* pH information from http://chemistry.about.com/od/acidsbases/a/phtable.htm
H. Obokata, T. Wakayama, Y. Sasai, K. Kojima, M. P. Vacanti, H. Niwa, M. Yamato, and C. A. Vacanti, Stimulus-triggered fate conversion of somatic cells into pluripotency,” Nature, vol. 505, no. 7485, pp. 641–647, Apr. 2015. doi:10.1038/nature12968
H. Obokata, Y. Sasai, H. Niwa, M. Kadota, M. Andrabi, N. Takata, M. Tokoro, Y. Terashita, S. Yonemura, C. A. Vacanti, and T. Wakayama, Bidirectional developmental potential in reprogrammed cells with acquired pluripotency,” Nature, vol. 505, no. 7485, pp. 676–680, Apr. 2015. doi:10.1038/nature12969
The accompanying picture shows: “Two NOD/SCID mice expressing enhanced green fluorescent protein (eGFP) under UV-illumination flanking one plain NOD/SCID mouse from the non-transgenic parental line.”. It is licensed under Creative Commons Attribution 2.0 Generic. The original source is: Ingrid Moen et al., “Gene expression in tumor cells and stroma in dsRed 4T1 tumors in eGFP-expressing mice with and without enhanced oxygenation,” BMC Cancer, 2012, 12:21. doi:10.1186/1471-2407-12-21