Objectives ethical difficulties
Stem cell therapy: Functional cardiomyocytes can be derived from pluripotent stem cells, and thus be used to repair damaged hearts. There are numerous experiments in this field. These cells have been specially derived from human embryos (embryonic stem cells) or from reprogrammed adult cells (iPS cells). The use of the former has the serious ethical difficulty that the cells have to be extracted from human embryos that must be destroyed, while there are technical difficulties to be resolved in the second before they can be used in human medicine.
Another added difficulty in using these cells in cardiac therapy is that it has so far been impossible to produce cardiomyocytes in the amounts necessary to be able to regenerate extensive heart lesions.
An article has now been published in Nature (510;273-277,2014), describing a technique to produce cardiomyocytes from embryonic stem cells in sufficient quantities to repair large hearts (in this case non-human primates); these were able to replace substantial amounts of damaged heart tissue in these animals.
The authors also mentioned that regenerating cardiac muscle in human hearts could also be possible, although potential complications, particularly arrhythmias, must first be overcome.
However, from an ethical point of view, it should not be forgotten that human embryonic stem cells are used to obtain the cardiomyocytes, with the ethical difficulty that this entails.