Announcement of Pr. Marc Peschanski on embryonic stem cells: a « spectacular demonstration », of what?


The ISTEM laboratory, issued from the joint Inserm/AFM unit and placed under the responsibility of Pr. Marc Peschanski, has just given out the results which were presented by their author as a « spectacular demonstration » of the interest of human embryonic stem cells (HES cells)

The announcement was made the day before the bill was examined by the Senate. The mass media coverage reveals scientific amalgams which brings forth interrogations on its true motivation.

a) An importance which needs to be put back into its right perspective.

Scientists know that it is currently impossible to find a treatment for patients from pluripotent stem cells (whether they are human embryonic- HES cells, or induced to pluripotency-IPS cells). Because of the risk there is for these cells not to differentiate properly, stay pluripotent, and develop tumours, in regards to the current knowledge researchers have, these cell are not used for making medication.

On the one hand, we have this pluripotent nature which constitutes a handicap in cell therapy and, on the other hand, it is coveted in the modelling and high-throughput screening of pathologies. HES cells are currently used as cellular material on which molecules which are potentially therapeutic are tested without restraint.

This type of application is used in the “demonstration” presented this morning by Pr. Marc Peschanski, on type 1 Myotonic Dystrophy (Steinert disease). We are not dealing with research on cell therapy, but research for pharmaceutical industries. Besides, three other elements help to put things back into their right perspective:

  • On the scientific level, the identification of pharmacological compounds or unknown mechanisms cannot be qualified as a “spectacular demonstration”.
  • The two compounds found are qualified as potentially useful in treating the pathology, though this still remains to be proven,
  • and HES cells are, actually, not essential in this perspective.

b) Scientific amalgams

What is being put forth by its authors is the causal link between the “spectacular demonstration” and the fact of using HES cells. As if they were, somehow, essential in the modelling of pathologies or the screening of molecules. They are not.

On the contrary, in this perspective, The IPS cells largely compete against HES cells because of two essential properties they have for these applications: pluripotency and immortality.

In terms of success, IPS cells largely overrun HES cells, because they are easier to access (by taking the samples directly from the patient whose pathology needs to be studied and reprogramming them in a laboratory) and, also, because there is no need to wait for the selection of embryos, carriers of the pathology, resulting from the in vitro fertilization/diagnosis/ lines derivation cycle.

And what about the obstacle the Pr. Peschanski mentioned to minimize the interest of IPS cells? He told the senators that they would have no alternatives because of reprogramming: “being cells induced to pluripotency, we start off by being very pragmatic (…) Reprogramming has apparently introduced a genomic, genetic default in these cells”. A precision enables one to understand what this really means.

The epigenetic traces that have been evoked and which can occur because of the process of cell reprogramming, could be negative if the aim of the research was to use them as material for cell therapy, i.e., if they were going to be applied to the patient. It is not the case. However, the epigenetic traces do not constitute an obstacle in the use of IPS cells for the applications concerned by today’s announcement (modelling and screening). This has been certified in several publications, one of them having been recently published in Nature Biotechnology 1.

Concerning this particular study, Pr. Preschanski has not brought the evidence that IPS cells would not be adapted in his research, as compelled by the law on bioethics.

c) What is the real motivation?

A quick reminder enables us to attempt to outline the beginning of an answer to this legitimate question by taking into account what is at stake on a political and ethical level. On the 20th of November 2009, during a press conference, Marc Peschanski announced he had managed to create epidermis from human embryonic stem cells.

This announcement was widely covered and commented by the media due to the fact it was presented as potentially applicable in treating serious skin pathologies: human embryonic research could enable to create temporary “plasters” for people suffering from serious burns or from Epidermolysis Bullosa, a serous genetic skin disease. Yet, not only were these perspectives out of the reach of the French team, but other teams of researcher had already found effective treatments for both these pathologies. The press conference was scheduled the day before the French “telethon” that finances Pr. Peschanski’s laboratory.