Dr Tolstoshev sees the possibility that stem cell technology may develop to this point, at which embryonic cells will not be required. "There is strong evidence for stem cell populations in adult tissues such as skin, blood and brain," he said. "These 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 strong 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. "If we can develop such technology we can avoid the moral and ethical issues," said Dr Tolstoshev, "but it is critical at this stage that we have access to human embryonic stem cells so that we can study the complex biology involved and assess their potential for cell therapy applications."
BresaGen is attempting to derive stem cells from normal adult cells, which would overcome the ethical issues associated with the isolation of embryonic stem cells and provide an immune-compatible source of cells for therapy. The research is following 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, which was used to produce Dolly, the worlds first cloned sheep. This could be done by fusing an adult cell with either an egg cell, or with an ES cell, that has had its genetic material removed, and then using the resulting stem cells to derive specialised cell types for therapeutic applications.
Although nuclear transfer technology has been used to clone several species including sheep, pigs, goats, cows, and mice, 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
Contact: Paul Tolstoshev