Biotechnology from an Embryonic Start

Thursday, 14 September, 2000

The biotechnology company, BresaGen, will receive human embryonic stem (ES) cells from the University of Wisconsin, USA. The cells will be used in the company's Cell Therapy Program, conducted in the Department of Biochemistry at Adelaide University.

Stem cells are the embryonic cells that first to appear as a fertilised egg develops. The cells have the ability to develop into most of the specialised cells in the human body including blood, skin, muscle and nerve cells. The cells also have the capacity to divide and proliferate indefinitely in culture.

Scientists use these two particular properties of stem cells to produce almost limitless supplies of most human cell types, offering opportunities for treatment by cell replacement. Cell therapy can potentially treat diseases associated with cell dysfunction or damage, including stroke, diabetes, Alzheimer's and Parkinson's diseases, heart attack, spinal cord injury, cancer and AIDS.

Scientists have been able to produce nerve, muscle and blood cells from mouse ES cells and would like to demonstrate the same transitions using human ES cells.

The source and acquisition of ES cells has raised ethical questions. One line was isolated from human foetal tissue obtained from terminated pregnancies and the other from surplus early-stage human embryos donated by individuals undergoing IVF treatment. It is cells from this second line that BresaGen and scientists will use.

Despite the fact that both tissue sources were donated with informed consent, the destruction of embryos for stem cell isolation has attracted criticism from pro-life, religious and bioethics groups.

The early-stage embryos used for the isolation of human stem cells are no more than six days old and are invisible to the eye. They are also composed of around 100-200 unspecialised cells and contain no specialised cell types such as those that make up the central nervous system, including the brain.

The isolation of stem cells from human embryos is legally difficult in Australia, but researchers are permitted to import cells that have been legally isolated in another country. Researchers from the Monash Institute of Reproduction and Development have obtained human ES cells in this way. Once isolated, stem cells can be handled under guidelines similar to those governing other human cell types.

As stem cells must be harvested from embryonic tissue, there is the possibility of an immune reaction when implanted into a recipient, an outcome associated with other organ and tissue transplants. There is also difficulty in obtaining sufficient donor cells. Both problems could be overcome if stem cells could be harvested from the patient that they are used to treat.

Researchers see the possibility that stem cell technology may develop to this point, where embryonic cells will not be required. There is evidence that stem cell populations in adult tissues may have the potential to form many of the specialised cells in the body, but they are very difficult to isolate and grow using current technologies. However, there are indications that researchers may be able to reprogram normal adult cells to form cells of an earlier developmental stage, possibly even to the ES cell stage.

BresaGen is attempting to derive stem cells from normal adult cells, with research taking two separate paths.

In the first, adult cells could be coaxed to form stem cell populations by manipulating the cell culture conditions. The alternative route would involve using nuclear transfer technology like that used to produce the cloned sheep, Dolly. This could be done by fusing an adult cell with either an egg cell or an ES cell that has had its genetic material removed. Then, the resulting stem cells are used to derive specialised cell types for therapeutic applications.

Although nuclear transfer technology has been used to clone several animal species, there is no evidence to suggest that the technology can be extended to humans. Furthermore, there is a world-wide ban on human reproductive cloning, and the majority of scientists, government authorities and bioethicists agree that human cloning offers no benefit to society.

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