subsequent development. This research may aid decisions about threshold levels when carrying out PGD, although it may be less relevant when considering the use of PNT or MST.
The panel categorised experiments that it feels are critical to assessing the effectiveness and safety of MST and PNT techniques (paragraph 5.4) and experiments that will provide useful information on MST and PNT or mitochondria and disease (paragraph 5.5). The former research will also inform which of the two techniques is likely to be the most appropriate for clinical use. Many of the latter experiments, whilst of potential importance for basic research and for possibly exploring alternative methods whereby abnormal mtDNA can be selected against, will not necessarily inform the decision as to whether it is safe to proceed to clinical application of MST and PNT methods.
The following (minimum) set of experiments is critical. These experiments should be undertaken and the results taken into account before MST and PNT techniques can be assessed as safe to use clinically:
MST using human oocytes that are then fertilised (not activated)
PNT using normally-fertilised human oocytes and development compared to normal ICSI-fertilised human oocytes
PNT in a non-human primate model, with the demonstration that the offspring derived are normal
The following additional research is recommended to provide useful information on mitochondrial disease and the MST and PNT techniques:
Removing the spindle or pronuclei and replacing them back into the same oocyte/zygote to better identify the impact of the manipulation technique
Karyotype analysis and comparative genomic hybridisation/copy number variation arrays of embryos derived from MST or PNT
Detailed analysis of epigenetic modifications and gene expression, with a range of markers for blastocyst cell types or embryos derived from MST or PNT Page 21 of 45