Alternative sources of stem cells – scientific bedrocks of a political decision
There are alternatives to human embryonic stem cells. Is the EU prepared to take the recent scientific advances into consideration when designing the next research framework programme?
At the end of last year a report confirmed the (first ever) cure of a patient infected by HIV after receiving an adult stem cell transplant from a donor who had natural resistance to this kind of infection. This was only one more case of the successful use of such cells reported recently. By contrast, it is well known that, despite the promises, human embryonic stem cells (hESC) have failed to meet expectations. The reasonable question here is “shouldn’t such facts be taken into consideration when drafting the new research framework programme to be applied from 2014 on”?
Regarding hESC, there is a deep divide among Member States and in European society in general linked to the insurmountable ethical problem posed by the fact that such cells can only be procured from human embryos at the stage of blastocysts that are thereby necessarily destroyed.
Because hESC present so many shortcomings a number of alternatives have been put forward. Some of these alternatives, however, still imply embryonic destruction. This is the case of hESC derived from so-called “therapeutic” cloning, or from human cytoplasmic hybrid embryos, created by transferring a human somatic cell nucleus not into a human oocyte but into an enucleated animal oocyte instead. The creation of cloned embryos which are incapable of being implanted or of developing after implantation (for example, embryos created by altered nuclear transfer) has been suggested for ethical reasons. Nevertheless, the fact that the embryo is defective, naturally or deliberately, does not alter its nature as a human being and, hence, the ethical assessment of such procedures. Alternatives using germ stem cells (including germ cells harvested from aborted foetuses) or using cells (blastomeres) collected by biopsy of an embryo during its early development, although not entailing embryonic destruction, still present other biological or ethical shortcomings.
However, three alternatives have proved excellent inasmuch as they offer no major biological or ethical problems: besides the abovementioned adult stem cells, there are also umbilical cord blood stem cells and, more recently, induced pluripotent stem cells. All these three types of stem cells can be differentiated into cells of almost all tissues of the human body, regenerating them (differentiating ability). As hESC, they also can proliferate without differentiating (self-renewing ability). But, unlike hESC, adult stem cells have been used therapeutically for many years, and umbilical cord blood stem cells are also used in therapies related to stroke and brain traumas, sclerosis, cerebral palsy, spinal cord injury or diabetes, to name only a few.
Coming to the third alternative, there have been constant scientific advances in the field of reprogramming of somatic cells through diverse techniques, namely genetic transfer (presented in 2006 by Yamanaka and colleagues). This consists of transferring genes responsible for pluripotency in stem cells in order to change somatic, specialized cells into undifferentiated cells, the so-called induced pluripotent stem cells. Although it is too soon for them to be applicable clinically, such cells, sharing basically the same biological characteristics and therapeutic potentialities of hESC, nevertheless also share with hESC some of their shortcomings: for example, both present risks associated with the formation of cancers at the injection points when directly transplanted into the subject. Although not perfect, such cells offer however some advantages, namely, they are clearly better suited than hESC for pathology modelling and, being collected from the patient to be treated, they eliminate the risk of immunological rejection which will always limit the possible clinical uses of hESC.
Taking into consideration all these facts, and in the light of the 2020 Strategy and its objective of “smart growth”, the political decision now is whether or not it is justified to have a results-oriented reallocation of EU funding, attaching relevance to the efficiency of research projects and their concrete impact on society. When the legislative initiative on the new research framework programme is presented late this year we will have a first glimpse of the answer.