Glass Bone Disease Change of collagen decrypted

Researchers explain the bone changes in the vitreous bone disease
The vitreous bone disease (osteogenesis imperfecta, OI) is characterized by an altered collagen structure in the bones. An international research team led by Philipp Thurner from the Institute for Lightweight Design and Structural Biomechanics of the Vienna University of Technology (TU) has now investigated how the structure of the so-called collagen fibrils changed and what effects this has on bone mechanics and resistance.

Using an atomic force microscope, the scientists analyzed the changes in collagen structure in mice with vitreous bone disease. Thurner and colleagues observed significant changes in the hydration or water uptake of collagen. This, according to the researchers, is also the cause of the reduced resistance of the bones. The study results were published in the journal "Journal of the Royal Society Interface".

The structure of collagen in vitreous bone disease has changed significantly. (Image: lculig / fotolia.com)

Altered water absorption in collagen
According to the scientists, significantly more water was bound in the collagen fibrils of the mice with glass-bone disease than in healthy animals. This had the effect in a dry environment that the bones of the diseased rodents were even more resistant to breakage or more elastic. "If one takes the collagen fibrils of a glass bones and compares them to those of a healthy mouse, the natural fibrils in the air are much stiffer than the morbid ones" , Thurner is quoted by the Austrian news agency "APA". However, the situation reversed with complete hydration. In an aqueous environment the healthy fibrils were much more elastic because they were able to absorb significantly more free water than those of the glass bones. The stiffness of the diseased collagen fibers was almost five times higher in the aqueous environment. One possible explanation for the reduced water absorbency of the fibrils of diseased animals is the already high content of bound water, leaving less room for unbound water. The environment with complete hydration corresponds approximately to the milieu in the body.

Treatment of vitreous bone disease possible?
However, in view of the increased brittleness of the bones, the observed increase in non-enzymatic crosslinks between the fibrils also plays a role. While the protein chains of collagen are usually bound together, especially at their ends, diseased mice show numerous cross-links between the fibrils, which in turn cause increased brittleness. The increased cross-linking "could be explained by an increased number of exposed amino acids," the scientists continue. So-called Advanced Glycation End Products (AGE) form the basis for the additional cross-links. Should this finding be transferable to human patients, "a procedure similar to that used in diabetes treatment could be used, i. The use of AGE inhibitors to counteract excessive accumulation of AGE, "the researchers concluded. (Fp)