Recommended Ethical Safeguards on Fertilization of Human Germ Cells Derived from Pluripotent Stem Cells Solely for Research Purposes.

Production of human fertilized embryos by using germ cells derived from pluripotent stem cells (PSCs) entails ethical issues that differ fundamentally depending on the aim. If the aim is solely to conduct research, then embryo generation, utilization and destruction must respect for the human embryo as having the innate potential to develop into a human being. If the aim is human reproduction, this technology must never be used to manipulate human life, confuse social order, or negatively affect future generations. Researchers should distinguish the aims and then accordingly establish a consensus on the safeguards needed to proceed with scientifically significant and socially accepted research, or otherwise set a moratorium. Currently, in Japan, germ cell production from human PSCs is permitted, whereas fertilization of these germ cells is not. The Japanese Expert Panel on Bioethics in the Cabinet Office has proposed that all of the following conditions must be met to approve fertilization for research purposes: (1) the research is significant for the life sciences and medicine; (2) the benefits or anticipated benefits are socially accepted; (3) human safety is assured; and (4) safeguards are put in place. If fertilization is ethically approved, I recommend the following safeguards: limitation of the purpose to improving conventional ART as an initial step; permitted culture of human embryos until the appearance of the primitive streak; restriction of the number of embryos produced to the minimum necessary; prohibition of transplantation into a human or animal uterus; and provision of human-derived ova that are not required for ART treatment.