Therapeutic Cloning

While initial research using embryonic stem cells was focused on using established embryonic stem cell lines, advances with cloning (specifically somatic cell nuclear transfer) led to the proposal that embryonic stem cells could be produced from adult cells.

These cells could be then used therapeutically and would be genetically identical to the person from whom they were taken. These cells would not be rejected by the patient's immune system.

To date, there have been no successful reported attempts for therapeutic cloning in humans (i.e. deriving embryonic stem cells from somatic cells), however this procedure has been successfully reported in mice. Nevertheless, this has led to a number of concerns being raised about therapeutic cloning in addition to those typically associated with embryonic stem cell research:

Reproductive cloning

A number of individuals and organizations who are not opposed to human embryonic stem cell research have expressed concern and/or opposition to the reproductive cloning of humans.

This is because both processes use the same first step: the creation of a clonal embryo, most likely via somatic cell nuclear transfer.

In research cloning, this clonal embryo will be destroyed in order to attempt to derive a stem cell line. In attempted reproductive cloning, the embryo would be implanted in a woman’s uterus to create a cloned child.

Those who hold this concern often advocate for strong regulation of research cloning., or its prohibition.

Sources of human eggs

A realted concern is the appropriate sourcing of the eggs that are needed in the first stem of research cloning. Due to poor reported rates of somatic cell nuclear transfer in other animals, it is likely that successful research cloning will require a large number of human eggs, which can only be obtained from women.

This is an invasive procedure that carries health risks, such as ovarian hyperstimulation syndrome, and even death.

Those who hold this concern call for measures to protect the women who provide eggs, such as requiring a "firewall" between clinicians carrying out the egg retrievals and researchers using the eggs in their work.

There are also concerns about the emergence of a market for eggs that would disproportionately lead economically vulnerable women to put themselves at risk.

This concern has led to a sentiment that prohibitions on financial compensation to women who provide eggs for research should not be compensated beyond reimbursement of direct expenses.

This position has been adopted by the United States National Academies and the California Institute for Regenerative Medicine.

Feasibility of cloning treatments

A final concern relates to the the feasibility of applying therapeutic cloning treatments. The large number of eggs and the skilled labor required may mean that any such therapies are likely to be impractical or extremely expensive.

Prominent researcher advocates such as Alan Trounson ("[T]he so-called therapeutic cloning to my mind is a non-event... it’s just not realistic [as a source of cures].") and Thomas Okarma ("[T]he process is a nonstarter, commercially.") have asserted that such therapies are not practical.

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