How Scientists Managed to Increase the Lifespans of Mice by 24%

Through one single treatment, scientists have managed to increase the lifespan of mice by 24% (1) with no side effects. In theory this treatment could one day be available for humans too. It sounds too good to be true, almost the stuff of science fiction… so what’s going on?

The Process

The study involved the use of gene therapy – the insertion of new DNA into the nuclei of mice cells in order to trigger the expression of new genes. This was achieved by using a genetically modified virus as the ‘vector’ (transporter) in order to ‘infect’ the cells with desirable genetic material.

The genetic material in question in this case, was a gene that would increase the production of an enzyme called ‘telomerase’. Telomerase is an enzyme which main purpose is to repair our ‘telomeres’. In most human cells, telomerase is produced prior to birth, but stops once we exit the womb.

What makes this so interesting, is that the role of the telomeres is essentially to reduce the effects of ageing. To understand this, it’s important to first understand the process that causes ageing.

Each time our cells divide, they split in half in order to create two new exact copies of the old cell. Only this process, called mitosis, isn’t quite perfect and will actually result in the slight degradation of the genetic material in the nuclei. This isn’t too important though, seeing as we have a ‘buffer’ region of unimportant information at either end of our DNA. Thus we can lose a little DNA each time the cells split and for a long time this won’t result in any visible change.

Unfortunately, once we reach adulthood, our telomeres start to run out and thus we begin to see our cells deteriorate. We call this ageing.

But seeing as telomerase can restore the telomeres, this can increase our lifespans. In an earlier study, the same process was used on mice in an embryonic stage and was then found to increase the lifespan by an incredible 40%.

Limitations

While this research is amazing, it’s important to recognize the limitations of the process. For starters, the therapy was more effective the earlier it was administered with two year old mice only seeing a 13% boost in lifespan.

Furthermore, gene therapy is as yet unsafe for regular use in humans. Unfortunately, we do not yet have a delivery mechanism (‘vector’) that is safe enough to be used without any risk of causing cancer. There is also a risk of triggering an immune response by using even genetically modified ‘safe’ viruses.

Moreover, there are also serious ethical considerations to consider before we begin routinely extending lifespan. While it might seem like a no-brainer, there would be a huge economic and cultural impact: things that will need to be considered before we see such treatments becoming mainstream.

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