Asexual Flatworms Hold Key to Immortality?

A team of researchers have discovered that the asexual flatworm overcomes the ageing process to be, potentially, immortal.

The scientists, working from the University of Nottingham, have found that planarian worms have the ability to regenerate; it can replace aged or damaged tissues. The project is being funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and the Medical Research Council (MRC).

The worms that were the subject of the experiments were of two types - sexually reproducing and asexually reproducing.

The experiment suggested that ageing cells were related to telomere length - a protective cap on the end of each strand of DNA. Essentially, the telomere stops strands from fraying or sticking to each other.

Apparently, in order to grow and function normally, cells in our bodies must keep dividing in order to replace worn out or damaged cells. During this process, copies of the genetic material encoded within each original cell must, obviously, pass on to the next generation.

The point is that each time a cell divides the protective telomere "cap" gets shorter. The shorter the cap gets, the cell progressively loses its ability to divide and renew itself. In an immortal animal, the cells should, theoretically, be able to maintain telemore length indefinitely; which is what the planarian worms seem to be able to do.

The team of researchers, led by Dr. Aziz Aboobaker of the University of Nottingham's School of Biology, indicated that sexually reproducing planarian worms did not maintain telomere length in the same way. The team suggested that sexually reproductive worms would eventually show the effects of telomere shortening. However, asexual planarian worms could theoretically maintain telomere length during regeneration.

Their next goal is to understand the mechanisms in more detail.

"Usually when stem cells divide - to heal wounds, or during reproduction or for growth - they start to show signs of ageing. This means that the stem cells are no longer able to divide and so become less able to replace exhausted specialised cells in the tissues of our bodies. Our ageing skin is perhaps the most visible example of this effect. Planarian worms and their stem cells are somehow able to avoid the ageing process and to keep their cells dividing," said Dr. Aboobaker.

"This exciting research contributes significantly to our fundamental understanding of some of the processes involved in ageing, and builds strong foundations for improving health and potentially longevity in other organisms, including humans," said Professor Douglas Kell, Chief Executive at Biotechnology and Biological Sciences Research Council.

The article was first published in Proceedings of the National Academy of Sciences (PNAS).