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Why has research on therapeutic cloning in humans been technically difficult?

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stem cell research — regenerative medicine A scientist conducting research on stem cells.

Research into therapeutic cloning in humans has faced significant technical and ethical hurdles. A primary technical challenge is maintaining embryo viability; the process of somatic cell nuclear transfer (SCNT) often requires numerous human eggs to produce a single viable embryonic stem cell line, yet human eggs are in short supply. Furthermore, the biological mechanism by which an unfertilized egg reprograms the nuclear DNA of a differentiated cell is not yet fully understood, leading to unknown risks.12

Beyond these technical difficulties, progress is hindered by significant ethical concerns. The procurement of human eggs for research purposes is fraught with legal and moral controversy, and many object to the creation and subsequent destruction of human embryos. Because of these challenges, the development of induced pluripotent stem cells—which do not require human eggs or cloning methods—has emerged as a significant alternative in the field of regenerative medicine. Ethical principles regarding the protection of human life and the prevention of exploitation remain central to the ongoing debate surrounding this research.13