The Promise of Somatic Cell Nuclear Transfer (SCNT)

How promising is somatic cell nuclear transfer (SCNT) providing embryonic stem cell therapies?

Answer: SCNT is a very inefficient process and requires hundreds to thousands of unfertilized eggs. Cloning has been accomplished in some animals like Dolly the sheep, but these animals had significant health and genetic defects. SCNT has never been accomplished in humans. Even if SCNT can be accomplished, there is no indication whether cloned stem cells will function properly and safely in a patient. Even if SCNT were successful it is not clear whether patients would be free from taking anti-rejection medication because mitochondrial genes would come from the donor egg cell, and there is a potential for exposure of foreign mitochondrial proteins that could cause tissue rejection. Even if SCNT were successful, patients may still require taking anti-rejection medications though the dosage may be lower. Thus, a patient could still be at risk for infection. There’s general agreement that patients with genetic disorders cannot be treated with stem cells from SCNT.

A more ethical alternative for producing human pluripotent stem cells has already been achieved with induced pluripotent stem (IPS) cells. IPS cells are adult cells that have been genetically reprogrammed into pluripotent stem cells. This process does not require using women's eggs to produce these cells or the creating of an embryo. However, with the recent success of human cloning, there remains debate among some scientists whether to use IPS cell technology vs cloning technology to create patient-specific pluripotent stem cells.