I work on the fringes of this area as some of the organizations I advise are involved in utilizing adult stem cells and umbilical cord blood stem cells (but not embryonic stem cells) in human tissue engineering. It is hugely complex field, both technically and ethically, and, in the European Union, different countries have adopted very different ethical approaches.

Stem cells may be derived from a number of sources:

Adult stem cells may be derived from bone marrow, blood, certain adipose tissues and some other tissues. Most countries and people have little problem with the use of adult stem cells but they are more limited in the types of tissues that can be differentiated from them as they are generally multipotent (or pluripotent at best).

Umbilical cord stem cells have a greater degree of potency and can be differentiated into a wider range of tissue types.

Embryonic stem cells are totipotent, i.e. they can differentiate into any kind of tissue, but raise the most ethical issues for reasons well explained above. Research on them is still banned in many countries, the UK being a notable exception in Europe.

Together with these issues, there are issues of accurately controlling what tissues, stems cells differentiate into. Using suitable growth factors, for example neural precursor stem cells can be made to grow into neural tissue, or other types of stem cell into myocardiocytes, opening up the possibility of very interesting new therapies for a number of serious diseases. One problem is controlling this growth so that unwanted tissues or tumour cells are not created, or that the tissue formed is properly vascularized.

Besides the ethical and moral issues already mentioned by others, there are many other ethical issues relating to the screening of donors, free or paid donation of cells and tissues, ownership of derived tissues, confidentiality, commercialization and the access of patients to such treatments. Technical issues include the traceability of tissues and safety issues such as the prevention of transmission of infectious agents and the management of numerous other risks relating to the use of derived cells or tissues, in tissue engineering, cell therapy or gene therapy. The last of these, gene therapy, also raises a further raft of scientific and ethical issues.

A complicated area and one where huge amounts of research, and ethical debate, have been and will continue to need to be done before a large number of envisaged new treatments reach the patient.

Peace

moo