By Alan Regenberg

Authors of a new paper published in Cell Stem Cell detail interesting results of what could be a step towards a treatment for the symptoms of Parkinson’s disease (PD). The press coverage of the publication provides an opportunity to once again advise caution against the temptation to overhype research results.

The researchers based in Sweden and France successfully demonstrate functional transplantation of dopamine neurons derived from human embryonic stem cells (hESCs) in a rat model of PD. In lay terms: neurons are put into rats’ brains, hook up correctly and fix PD-like symptoms that have been caused by damaging the rats’ brains, and, furthermore, hook up in a way that suggests that they might just work for humans with PD.

While I haven’t seen press coverage that is wildly inaccurate, I think that some of the headlines have been misleading:

The BBC writes “Parkinson’s stem cell ‘Breakthrough’: Stem cells can be used to heal the damage in the brain caused by Parkinson’s disease, according to scientists in Sweden.”

 

ITV news’ headline: “Major breakthrough puts scientists on path to first ever stem cell transplantations in people with Parkinson’s disease”

A more minor issue here, the stem cells themselves aren’t being transplanted, rather it is dopamine neurons (derived from hESCs) that are transplanted.

More importantly, I think that the focus in these headlines on “Parkinson’s disease”, along with an image of a human brain, implicitly suggest that these results prove that this intervention works in humans, which is not something we ought to be implying.

This paper describes results using a rat model of PD. Animal models are imperfect, and can leave many questions unanswered. Channeling the findings of an expert working group, I wrote about this, in a 2009 paper. Discussing the role of animal models for human trials of cell-based interventions for neurologic conditions, we singled out PD models as an area of particular concern:

“Animal models for Parkinson’s disease (PD) primarily rely on toxins to recreate the loss of dopaminergic neurons in the nigrostriatal pathway. Although this successfully mimics important symptoms of PD, and allows testing of interventions targeting these symptoms, it does not capture the full pathologic study and more importantly, it does not model the chronic progression of PD.”

In other words, this study is undoubtedly great news for rats given the symptoms of PD with toxic injections. And the results are consistent with what we would want to see if this was going to work in humans, but, there is plenty of room to explain away discrepancies if, like dozens of stroke treatments, this intervention works in animals but not in humans.

Another concern, in the new study, hESC-derived dopamine neurons seemed similar to fetal neuron grafts. Fetal tissue transplantation for PD has a pretty long history, with the first transplants in human patients occurring over 20 years ago, with somewhat mixed results. The intervention treats motor symptoms of PD, and will not cure the disease itself.

I think the sample headlines suggest a more robust treatment than something that can manage the symptoms of PD for some patients. Certainly “heal the damage” seems to go beyond the actual results.

It’s also worth noting that the authors, in describing fetal tissue transplantation, explain that “the use of tissue from aborted human embryos presents several ethical and logistical issues that hamper the effective translation of fetal tissue transplantation as a realistic therapeutic option.”

The authors seem to underestimate the extent to which those concerned about the use of tissue from aborted embryos are likely to be similarly opposed to the destruction of embryos for the creation of hESCs. I suspect the use of hESC-derived neurons represent a lateral move on this particular ethics front.

I understand that headlines can’t be overly bland. And, I’m not suggesting that we ruin the news by leeching the excitement out of discoveries. I also understand that news outlets have papers to sell (or the modern day equivalent, websites to traffic?), and results like these are actually pretty exciting.

That said, headline writers should be very cautious about even implicitly misleading readers, particularly in the context of environments like that of stem cell science where hope and hype have played such important roles in the ethical and political struggles over its development.

Alan Regenberg, MBe, is not a nurse. He is the Director of Outreach and Research Support at the Johns Hopkins Berman Institute of Bioethics. Among other things, he is working on developing and implementing strategies to use social media as a tool for broad public engagement around issues in bioethics. You can follow him: @aregenberg, and he curates the twitter feed: @bermaninstitute

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