Early phase of atherosclerosis imaged

The images made by researcher Nico Sommerdijk (Laboratory of Materials and Interface Chemistry, Department of Chemical Engineering and Chemistry) and his team resolve a long-standing dispute. As long ago as 1965, Aaron S. Posner suggested in the journal Nature how the calcification -- the formation of calcium phosphate -- in a biological environment takes place, although this met with considerable resistance at the time, Sommerdijk explains. However, his observations now confirm Posner's 45-year-old idea.

Calcium and phosphate ions dissolved in the blood are not deposited directly as crystalline material on the artery wall, but first pass through an intermediate phase. In this phase they first form prenucleation clusters, followed by amorphous nanoparticles measuring approximately 50 nanometers (1 nanometer is a millionth of a millimeter). Only then does crystallization occur, causing hardening of the artery wall. The researchers hope that this understanding will be used to develop new forms of treatment for atherosclerosis.

Serum

Because atherosclerosis cannot be observed at a nanometer scale in living persons, the researchers used imitation serum -- a fluid containing exactly the same substances as those found in the blood itself, except for the organic materials. The researchers placed this serum in contact with a membrane with the same characteristics as the artery wall, on which the process of calcification then began. They imaged the various steps of this process using a special electron microscope, the cryoTitan. This microscope allows researchers to observe very rapidly frozen samples at the level of individual atoms, so that a process can be arrested and viewed step-by-step.

All living beings

Sommerdijk has already showed that the process of shell growth and bone formation takes place in the same way as atherosclerosis. "It seems that all mineralization systems in living beings take place in the same way. And there are increasing indications that it works similarly everywhere," says Sommerdijk.