Scientists have discovered a shock-absorbing ‘goo’ in bones which helps prevent them breaking and could lead to treatments for osteoporosis.
Researchers at Cambridge University found a viscous fluid trapped between tiny crystals within bones which makes them more flexible and less likely to shatter.
The gooey fluid – called citrate – makes up around half of all bones and had not been previously identifed.
The scientists say the discovery could revolutionise the treatment of the bone disease osteoporosis.
Bone tissue has a protein mesh with holes where calcium is deposited.
In healthy tissue, the holes are very small, trapping citrate which is a ‘spidery’ molecule which bonds easily to calcium.
But as people age or suffer repeated bone trauma the protein mesh does not repair so well and larger holes form in the protein mesh.
The scientists believe osteoporosis could be triggered by citrate leaking out, leaving bone crystals increasingly brittle and more likely to break.
Dr Melinda Duer, who led the study, said: “In the bigger holes in damaged tissue, pure chemistry takes over.
“Pretty much the moment calcium and phosphate touch, they form a solid.
“You end up with these expanding clumps of brittle crystal, with water and citrate relegated to the outside of them.
“In terms of chemistry, that solid clump of mineral is the most stable structure.
“Biomechanically, however, it’s hopeless – as soon as you stand on it, it shatters.
“If we want to cure osteoporosis, we need to figure out how to stop the bigger holes forming in the protein matrix.”
The team from Cambridge’s Department of Chemistry used a combination of NMR spectroscopy, X-ray diffraction, imaging and high-level molecular modelling to reveal the citrate layers in bone.
Dr Duer added: “Bone mineral was thought to be closely related to this substance called hydroxyapatite.
“But what we’ve shown is that a large part of bone mineral – possibly as much as half of it in fact – is made up of this goo, where citrate is binding like a gel between mineral crystals.
“Without citrate, all crystals in bone mineral would collapse together, become one big crystal and shatter.
“It’s this layered structure that’s been missing from our knowledge, and we can now see that without it you’re stuffed.”
The study was published yesterday(Mon) in the journal Proceedings of the National Academy of Sciences.
