|Professor Jonathan Slack,
Professor of Developmental Biology at the University of
Bath, has produced headless or tailess tadpoles by
genetic manipulation of frog eggs.
The experiments are part of a series which have explained the molecular basis of how the head-tail-trunk pattern is formed during animal development. A type of signalling substance, called fibroblast growth factor, is released from cells in the future tail region. This stimulates other cells in the rear half of body cells to activate genes of the cdx class which in turn activate genes of the Hox class.
Hox genes exist in all animals from worms to humans and are already known to be key regulators of head to tail pattern in embryos.
Developmental biology has undergone a renaissance in the last 15 years and progress in understanding of the molecular basis of development has been very rapid. It is now known that for fundamental processes, such as those discovered by Professor Slack, all vertebrate embryos (ie, fish, frogs, birds, mammals) are very similar. It is therefore highly probable that similar genes will do the same job in human embryos.
Basic research in developmental biology promises to lead eventually to novel strategies for the treatment of degenerative diseases such as cancer, diabetes, arthritis or neurodegeneration. As Professor Slack says, "You can only really know how to fix something if you know how it was put together in the first place".
The present work has also raised the possibility of using the technology to grow organs for human transplantation. This is now a theoretical, but not a practical possibility.
The advantages of growing an organ from the patient who needs it are twofold. Firstly, it is genetically identical so there is no problem of immunological rejection. Secondly, it would help reduce the chronic and worsening shortage of donor organs.
The procedure would involve culturing cells from the patient, which could be from any tissue, eg, white blood cells, then introducing into these cells genes which would suppress the development of the remainder of the body except the organ required. The cells would then be fused to an enucleated egg and allowed to develop until it was large enough for grafting. To support development an "artificial placenta" would be required.
Professor Slack said he felt this was a theoretical possibility although its practical realisation was probably 10-15 years away. He said, "There are huge ethical and legal issues here. It is important to discuss these things before they become a practical reality in order to get the regulatory and legal framework right." He said, "In my view, creating anything that resembled a human embryo in appearance, or any procedure involving surrogacy, would be out of the question."
For further information please contact the Public Relations Office at the University of Bath on 01225 826631.