The report by Michael West and his colleagues, from a private company in the USA, that human embryos of a few cells (6- to 8-cells) can be made by the nuclear transfer technique used to make
Dolly the sheep, has produced considerable interest and comment.
The intent by West was to show that embryos and eventually embryonic (pluripotential) stem cells could be made to correct serious diseases for patients. He strongly opposes the cloning of a
person. The ability to take cells from an adult mouse to make embryonic stem cells that can make all the cells of the body has already been shown by researchers at Monash University and confirmed
Why do these human experiments? There are few embryonic stem cells available at the present time and tissue formed in the body from these cells might be rejected. So for clinical use of stem
cell therapies, it might be necessary to make cells of specific type, or from specific patients, to prevent rejection.
However, it is very early in the research on stem cells, and scientists still need to demonstrate that these cells can be directed into all the cell types necessary and these will cure diseases
in animal models. The human experiments are premature in this regard.
Is the report significant? The production of embryos of a few cells is a very small step forward for stem cell therapies. Embryos produced by this method in animals often do not develop any
further than a few cells. There was no attempt to make embryonic stem cells so there is no information on the capacity of these early embryos to develop further.
Given the experiments in mice, we could have expected that the technique will work. So rather little scientific information has been produced by West’s experiments.
Do we really need to use the nuclear transfer technique used to produce these embryos? This is unlikely. Large numbers of mature human oocytes – eggs – are needed. It is calculated from the
experiments on mice that around 100 oocytes are needed to produce an embryonic stem cell for a patient. It is most unlikely that this many oocytes can be provided in the future for sick patients.
Other alternatives exist and research is already well advanced on more likely options. This includes the identification of proteins of the oocyte that actually reprogram cells to be new tissue
types. These proteins can be synthesized and used to redirect cells into the desired cell type.
There are also reports of fusing adult cells with embryonic stem cells to produce new cell types. These techniques are more likely to be used in the future, avoiding the need for human oocytes
and production of early embryos.
The importance of stem cell research to help patients with serious disease and injuries shouldn’t be lost in the debate about the production of a few cleavage stage embryos of unknown
capacity to develop further.
Research is needed on the full range of options that exist for deriving stem cells for cell therapies. It is also crucial to demonstrate that these pluripotential stem cells can correct
degenerative disorders or injuries.
There are concerns that the report by Michael West and his colleagues may distract researchers from achieving the very considerable potential of stem cell therapies to reverse handicap and
disease. This must remain our primary objective and this includes the solutions to incompatible transplants that do not involve the sourcing of large numbers of human oocytes.
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