Wednesday, 4 April 2012

Tissue Regeneration Without Scars

BIOL1020 – Genetics Blog

Genetic Discovery Promises healing Without Scars


I was recently forced to sit through the Disney movie ‘Hercules’ because according to my girlfriend my childhood was wasted playing the gameboy. In the movie, Hercules fights a monster known as the Hydra, which is basically a mythical lizard-snake which can regenerate multiple heads. Being a typical boy I thought how cool the ability to regenerate tissue perfectly would be to human beings. In the field of surgery; the idea of no nasty scars renders surgery a much less daunting option for those who need it. In the military field; soldiers who experience a wound in battle, such as a loss of a limb, could simply regrow the lost tissue.

For many years this concept has remained material of science fiction and comic books, as seen in X-men by the character Wolverine. However, a recent discovery has led to the idea that one day; human beings could have the ability to regenerate tissue without leaving any scars. In late 2009, K. Bedelbaeva et al discovered that mice that lacked the p21 gene could regrow tissue without leaving scars. The theory behind this discovery came from observing newts regrow entire limbs. It was theorised that perhaps throughout evolution, this ability to regrow tissue died off due to the lack of predator threats and that somewhere in their genes, mammals possess the dormant ability to also regrow tissue. Thus, it was found that by switching off the p21 gene, genetically engineered mice could regrow tissue successfully.

Without the p21 gene, adult cells act the same as stem cells. That is, they have the ability to differentiate into any type of tissue cell and hence, via mitosis form brand new appendages. The p21 gene is disrupted by the insertion of artificial DNA, this is known as ‘knocking out’ the gene. It is performed to observe the change that a single gene has on the organism’s phenotype. The genetically engineered mice had holes punched into their ears and it was seen that after a period of time, there was no trace that a hole had even been punched. However, the p21 gene is controlled strictly by the gene p53, which acts as mitotic regulator and a tumour suppressor. Therefore, if the p21 gene is disrupted it can lead to dysfunctional p53, which can lead to numerous cancers. Not only that, but the gene p21 itself acts to prevent cancer by stopping mitosis of any cells with damaged DNA. It was theorised that the mice without this gene would suffer from cancer formations, but whilst there was increased DNA damage, minimal cancers where found, instead a high rate of apoptosis (cell suicide) was observed.

Although this concept sounds appealing and viable, the fact that the p21 gene acts as a safety control mechanism for cancer, means that there is much risk for this technique. For the short time the gene is inactive, the chances of the patient’s cells becoming cancerous increase greatly. So whilst the applications of this concept are appealing, the risk of dying outweighs the chance of having no scars after surgery. So it appears humans still can’t compare to Wolverine… for now.

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