21 November 2018
Samples of human femur and humerus (leg) bones were tested. Some were untreated, while others were treated with either chemicals or enzymes to remove organic matter.
(Image: Royal Society of Chemistry)
A team from Portugal have used ISIS Neutron and Muon Source to analyse bone that has been treated for use in medical grafts in the hope it will lead to more effective and safer bone implants in the future.
The human skeleton has a remarkable ability to regenerate and heal even really bad breaks – all it requires is to be set correctly, immobilised with plaster, and given plenty of time. But if bone has been lost because of a catastrophic break, chronic disease, or major surgery, our bones can need a little help to get the job done. This is done with use of bone grafts, which replace lost bone and provide a scaffold around which new bone can form.
In ideal circumstances, the bone used in a graft will come from another part of the patient’s skeleton (called an autograft), such as the ribs, hips or pelvis, but this isn’t always possible due to shortage of donor material. The next, rather macabre, option is to take bone from a diseased donor, or cadaver, (called an allograft). When a human donor isn’t available, surgeons will turn to using bone from other animals, such as cows and pigs, which is known as a xenograft.
As unlikely, or perhaps unpalatable, as they sound, xenografts have been shown to be extremely compatible with living human bone and can be used as a reliable tool to promote new bone growth.
The problem with using allografts and xenografts is the potential for the transmission of disease from the donor to the patient and that the foreign bone might be rejected by the patient’s body.
To minimise this risk, the bone must be stripped of all of the fats and proteins that once belonged to the donor – leaving only the bare scaffold, or matrix, or the bone – essentially making sure that nothing is left behind that might carry infection or prompt an immune response in the patient.
Unfortunately, it is not that easy to completely remove all of the fats and proteins, which make up some 25 per cent of the untreated bone material. There are several methods of achieving this, but the trick is doing so without damaging the structure bone matrix.
The team from the University of Coimbra, Portugal, used ISIS Neutron and Muon Source to investigate samples of untreated bone and bones that had been treated using two different methods – one that involved treating the bone with high temperatures and another that uses an alkaline liquid – to see just how effective each is at removing both fats and proteins.
They found that one of the methods was particularly effective at removing fats, while the other was particularly good at removing proteins, but that neither managed to eliminate them both.
They then compared the results of these older methods with a newly-developed technique that treats the bones with enzymes to break down the organic material. Previous studies had proven inadequate for identifying the very small amounts of fats and proteins that are left after treatment.
By using neutrons, which allow scientists to study samples at a molecular level, the team was able to determine that the multi-enzyme technique was very effective at eliminating proteins but only partially effective at removing the fats. The technique did manage to achieve this without damaging the bone’s vital matrix structure. The hope is that, by using the information gathered at ISIS, the new method might be fine-tuned so that it is completely effective – a result that would have a huge impact on regenerative medicine.
Last updated: 25 February 2019