Stem cells are unique in that they are unspecialised (blank cells if you like) and are able to proliferate which simply means that they can multiply and make exact copies of themselves. Stem cells are also pluripotent meaning that they have the potential to become any type of adult cell and this process of specialisation is known as differentiation. Stem cells can differentiate into one of three types which are collectively known as the germ layers. The three types are as follows;
Ectoderm – The outer layer. Gives rise to the epidermis (skin), hair, pigment cells, central nervous system (brain and spinal cord), sensory neurons and facial bones/tissues.
Mesoderm – The middle layer. Gives rise to the circulatory system (heart, blood and vessels), kidneys, gonads (ovaries/testes), muscle, bone and connective tissue.
Endoderm – The inner layer. Gives rise to lungs, thyroid and digestive organs i.e. stomach, liver, intestines, pancreas etc.
Endoderm – The inner layer. Gives rise to lungs, thyroid and digestive organs i.e. stomach, liver, intestines, pancreas etc.
The diagram below illustrates the process of how stem cells are produced.
The maturation of stem cells
After conception, a tiny cluster of cells is formed which is called a blastocyst aka outer layer trophoblast. Stem cells can be derived from one of the following four origins.
Embryonic – cells are taken from the inner cell mass of the blastocyst.
Fetal – the embryo changes into a fetus and cells are extracted at the fetus stage.
Fetal – the embryo changes into a fetus and cells are extracted at the fetus stage.
Cord Blood – Cells are taken from the umbilical cord and placenta after birth.
Adult – cells are taken from adult tissues and are found in a variety of locations such as; brain, eyes, liver, skin, muscle, bone marrow and blood (see diagram below). Research into other possible sources of adult stem cells is still ongoing.
On second thoughts, the stages of maturation may be a more appropriate description of where/how stem cells can be derived. And herein lies the crux of problem; the reason why stem cells cause so much uproar in the media…
The main focus of protestors is the use of embryonic stem cells. In order to obtain embryonic stem cells, the human embryo has to be destroyed. As the embryo is classed as a human being, the destruction of the embryo amounts to murder, which is morally wrong. Furthermore manipulation of embryos could lead to reproductive cloning which in turn would to human life being devalued.
The utilitarian argument is that it is not fair to assume that embryo’s have an equal value as human life as they cannot survive independently outside the womb. In the natural female cycle, a lot of zygotes do not get implanted in the womb and are lost due to natural causes. Therefore rationally it is fair to say that a lot more embryos are lost naturally as opposed to the number of embryo’s that are used in research. Also as the embryos have no distinguishable organs, this means that they are no more human than a skin cell and should not be treated any differently. So there you have both sides of the argument, but where does that leave us in practical terms?
Please note that reproductive cloning is a different issue compared to therapeutic cloning i.e. developing therapies for diseases – think Dolly the sheep.
- Therapeutic cloning – adult cells for use in medicine and is an active area of research (see diagram below)
- Reproductive cloning – Involves making cloned humans
- Replacement cloning – theoretical possibility; combines therapeutic and reproductive cloning. It would entail the replacement of an extensively damaged and failing body via cloning followed by whole or partial brain transplant.
Embryo research in Britain is controlled by the Human Fertilisation and Embryology Agency (HFEA). Although there are no laws at present to stop human cloning, the manipulation of embryos does require a licence that has to be issued by the HFEA and the UK government are also looking into bringing in legislation to make human cloning illegal for reproductive purposes.
State of affairs to date in the UK
On 14 January 2001 the British government passed the Human Fertilisation and Embryology (Research Purposes) Regulations 2001 to amend the Human Fertilisation and Embryology Act 1990 by extending allowable reasons for embryo research to permit research around stem cells and cell nuclear replacement, thus allowing therapeutic cloning. However, on 15 November 2001, a pro-life group won a High Court legal challenge, which struck down the regulation and effectively left all forms of cloning unregulated in the UK. Their hope was that Parliament would fill this gap by passing prohibitive legislation. Parliament was quick to pass Human Reproductive Cloning Act 2001 which explicitly prohibited reproductive cloning. The remaining gap with regard to therapeutic cloning was closed when the appeals courts reversed the previous decision of the High Court.
• In Germany, for example, all embryo research is banned. Any attempt to clone a human would therefore be outlawed.
• Legislation is already in place that would prevent human cloning in Brazil, Mexico, Saudi Arabia, South Africa, and most of Europe and Australia.
• Guidelines are in place in Argentina, Canada, the Czech Republic, Egypt, Israel, Japan, Jordan, Singapore and Korea.
• In the United States, there is no federal law specifically banning human cloning but some states, such as Michigan, have civil controls.
So which countries completely outlaw human cloning at this moment in time. Well it is a little confusing but I would think the answer quiet simply is none of them and what we really need is for all the countries to get together and produce an international set of rules that are applicable to all countries.
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