Japanese researchers have successfully “cured” Parkinson’s-like symptoms in crab-eating monkeys by implanting nerve cells derived from stem cells into their brains.
[Associate Prof. Jun Takahashi of Kyoto University’s Institute for Frontier Medical Science and his] research team used the embryonic stem cells to cultivate a cell mass in which 35 percent of the cells were dopamine-producing neurons.
These neurons then were transplanted into the four crab-eating monkeys, whose conditions were observed over a one-year period.
According to the study, the monkeys exhibited reduced shaking of their limbs half a year later. They had remained nearly motionless inside their cages all day long before the transplant, but the improvement of their symptoms eventually enabled them to occasionally walk around the cages.
This is positive, albeit distinctly uncomfortable. My understanding is that monkeys do not get Parkinson’s (even in a laboratory); it is a uniquely human condition. So, these creatures did not have Parkinson’s per se. l suspect that the researchers did something to knock out the dopamine-producing neurons, thus mimicking the effects of Parkinson’s. This is one problem: they were not treating the true condition. Then there are a pair of ethical issues. Animal research is inherently problematical, and it is a topic that l have complicated feelings about. Embryonic stem cell research is hugely controversial in some quarters (especially in right-leaning religious quarters). However, less controversial alternatives do exist:
Takahashi said so far he had used embryonic stem cells, which are harvested from foetuses, but would likely switch to so-called Induced Pluripotent Stem (iPS) cells, which are created from human skin, for the clinical trial.
And this despite the fact that “The Japanese government currently has no guidelines on the use of human stem cells in clinical research.”
The positive aspects? Well, it’s a step towards a potential cure. Not just a slowing of the condition’s progress, nor even a cessation of neuron-loss (either of these would be welcome), but an opportunity to regain those lost neurons – to turn back the clock to the days before Parkinson’s. lt’s a nice thing to contemplate.
But – even laying aside the fact that the poor monkeys did not, actually, have Parkinson’s; even considering that the improvement in symptoms was based purely on observation of the monkey’s ability to move and their level of tremor (you can’t get a monkey to tell you how it feels) – even then, there are many obstacles. Monkeys are not the same as humans. What works in monkeys may not work with us. There may be as yet unknown risks with the procedure. It’s brain surgery, after all. It looks like the researchers are bowing to the pressure and will be switching to induced pluripotent stem cells, which, one suspects, may not work in quite the same way. And, of course, clinical trials will take a long time to prove the efficacy of such treatment.
So don’t go getting too excited. Yet.
The abstract for the paper can be found here.
The news articles focus on the “success” of the treatment. The academic paper – accepted for publication in the US journal Stem Cells – is entitled “Prolonged Maturation Culture Favors a Reduction in the Tumorigenicity and the Dopaminergic Function of Human ESC-Derived Neural Cells in a Primate Model of Parkinson’s Disease” and is focused on the fact that the stem cells were developed in the laboratory before implantation, and that this approach seems less likely to cause brain tumors. The easing of the monkeys’ symptoms is almost an additional bonus.