Risks, Ethics and Plant Cloning Benefits

Why stem-cell use requires evaluation

Stem cells can divide and can give rise to specialised cells. This creates possible medical benefits: damaged or missing cells might be replaced, potentially helping people with serious conditions such as diabetes or paralysis. However, a possible benefit does not by itself show that a treatment is safe or ethically acceptable. An evaluation must weigh the likely benefits against practical risks and objections.

Medical risks

A specific risk named in the specification is the transfer of viral infection. If transplanted stem cells carry a virus, that virus could enter the patient and cause infection.

Cells grown in culture also need careful monitoring. Mutations have been observed after many cell divisions, and cultured stem cells can show similarities to cancer cells. Altered cells might behave abnormally, so researchers must investigate the safety and success of a treatment before its potential benefit can justify its use.

Cells obtained from another person may also be recognised as foreign and rejected by the patient's immune system. A close match between donor and patient reduces this problem, while medicines that suppress the immune system can make a patient more vulnerable to infection. Therapeutic cloning can reduce rejection because the resulting embryonic stem cells have the same genes as the patient, but producing and then discarding an embryo creates further ethical objections.

Ethical and religious objections

Embryonic stem cells are removed from a human embryo, and the embryo is destroyed or discarded. Some people therefore object to their use. Some religious believers hold that human life begins at conception and that an embryo consequently has moral status or rights. From this viewpoint, deliberately creating or using an embryo in a process that destroys it is unacceptable.

Other people place greater weight on the possibility of reducing suffering or treating serious disease. They may also argue that some embryos left over from IVF treatment would otherwise be destroyed. These arguments do not make one conclusion automatically correct: views depend partly on when a person believes human life gains moral status and whether the expected medical benefit is judged sufficient to outweigh the destruction of an embryo.

The source of the cells therefore matters. Adult stem cells do not require an embryo to be destroyed, so they avoid that particular objection, although they cannot necessarily form as many different cell types. An effective evaluation should distinguish such ethical concerns from scientific risks and should acknowledge that not all religious people or ethical viewpoints reach the same conclusion.

Cloning plants from meristems

Meristems are growing regions containing plant stem cells. These cells can differentiate into any type of plant cell throughout the plant's life. Pieces of suitable plant tissue can be cultured to produce many new plants with the same genes as the parent. The resulting plants are clones.

This has an important economic use in farming. If a crop plant has a valuable inherited feature, such as disease resistance, cloning can produce large numbers of identical plants that retain that feature. Producing clones quickly and economically allows farmers to multiply a useful crop without waiting for repeated sexual reproduction, and the uniform plants have predictable inherited characteristics.

Plant cloning can also support conservation. A rare plant can be multiplied to increase the number of individuals and help protect the species from extinction. Tissue culture is particularly useful because many plants can be produced from a limited amount of the original plant material.

There is an important distinction, however: cloning increases the number of plants, not their genetic diversity. All the clones carry the same genes as the parent. The conservation benefit is therefore the rapid multiplication of scarce plants; it does not create new genetic variation.

Stem-cell risks

• Transplanted cells may transfer a viral infection to the patient.
• Cells grown through many divisions may acquire mutations and behave abnormally.
• Donor cells may be rejected as foreign by the immune system.
• Immunosuppressant medicines can reduce rejection but increase vulnerability to infection.

Ethical and religious objections

• Obtaining embryonic stem cells destroys or discards an embryo.
• Some people believe that life begins at conception, so an embryo has moral status or rights.
• Others argue that treating serious disease and reducing suffering may outweigh the objection, particularly if spare IVF embryos would otherwise be destroyed.
• Ethical objections and biological risks are different and should be evaluated separately.

Meristem cloning

Meristem cells can form any plant cell type throughout a plant's life. Culturing them can produce many genetically identical plants quickly and economically.

• Farming: clone a crop with a useful feature, such as disease resistance, to produce large numbers with the same inherited feature.