The answer
Stem cells can be extracted from very young human embryos, typically from surplus frozen embryos left over from in-vitro fertilization procedures at fertility clinics. The Church regards a few-day-old embryo a human person. Extracting its stem cells kills the embryo, an act that is considered murder. Stem cells can now be grown in the laboratory, so some research can be done using existing stem cells. No further harvesting needs to be made from embryos. However, existing stem cell lines are gradually degrading and will soon be useless for research which will mean requiring new embryos.Instead of defending Stem Cells Research from these embryos we need to discourage the in-vitro fertilization where many embryos are killed daily.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)