Day 077 - Intracellular junk

Submitted by Sam on 5 August, 2011 - 22:51

Lysosomes are organelles that act as cellular recycling machinery, breaking down large molecules, waste material and damaged cellular subcomponents using digestive enzymes bathed in an acidic environment. Whilst extremely effective as a waste disposal system, there are some chemical structures that the cell's degradation machinery is simply unable to break down. Over time, these resilient compounds build up in the lysosome as useless junk. This is typically not a problem in cells such as skin cells which divide regularly, as the cellular division distributes the junk at harmlessly low levels. In cells which do not divide so frequently, like those in the back of the eye and some nerve cells, the material accretes to harmful levels, damaging the cells and eventually stopping them working correctly. Unstable build-ups of this material eventually burst, and can cause heart attacks and strokes, whilst failure to remove the intracellular junk in the brain can lead to neurodegenerative diseases such as Alzheimer's and Parkinson's. Macular degeneration, the leading cause of age-related blindness, is also caused by the accumulation of the toxic components of this lysosomal residue.

Lipofuscin is the general term for this undegraded waste material, and it is one of the seven types of ageing damage identified by Aubrey de Grey and combated by his Strategies for Engineered Negligible Senescence (SENS). The proposed strategy for dealing with the age-related pathologies of lipofuscin build-up is to confer lysosomes with enzymes capable of digesting the relevant material using gene therapy.

The feasibility of this solution is given credence by an incidental property of lipofuscin and some cross-disciplinary thinking by Dr. De Grey. Lipofuscin is fluorescent, but graveyards and mass graves don't glow in the dark. What this means is that the soil, which should be unusually full of the intracellular waste from decaying bodies, should itself fluoresce; the fact that it doesn't suggests that it contains some substance capable of degrading the enzyme-resistant lipofuscin. Soil mirco-organisms have been known for some time to be capable of digesting solvents, pesticides and oil into harmless products, and so De Grey reasons that there are bacteria in the soil containing an enzyme capable of cleaning up our intracellular junk.

Our not-insignificant task now is to identify this enzyme and equip our cellular recycling plants with its powers. With this new potency to degrade even the most resistant materials, their pathological accumulation would not just be mitigated, but may also be reversed, as ageing cells all over the body would be purged of their toxic cargo. In the case of macular degeneration, this reversal would allow the blind to see.

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