Shining a new light on biological cells

Combined X-ray and fluorescence microscope reveals unseen molecular details

A research team from the University of Göttingen has commissioned at the X-ray source PETRA III at DESY a worldwide unique microscope combination to gain novel insights into biological cells. The team led by Tim Salditt and Sarah Köster describes the combined X-ray and optical fluorescence microscope in the journal Nature Communications. To test the performance of the device installed at DESY’s measuring station P10, the scientists investigated heart muscle cells with their new method.

Modern light microscopy provides with ever sharper images important new insights into the interior processes of biological cells, but highest resolution is obtained only for the fraction of biomolecules which emit fluorescence light. For this purpose, small fluorescent markers have to be first attached to the molecules of interest, for example proteins or DNA. The controlled switching of the fluorescent dye in the so-called STED (stimulated emission depletion) microscope then enables highest resolution down to a few billionth of a meter, according to principle of optical switching between on- and off-state introduced by Nobel prize winner Stefan Hell from Göttingen.

>Read more on the PETRA III at DESY website

Image: STED image (left) and X-ray imaging (right) of the same cardiac tissue cell from a rat. For STED, the network of actin filaments in the cell, which is important for the cell’s mechanical properties, have been labeled with a fluorescent dye. Contrast in the X-ray image, on the other hand, is directly related to the total electron density, with contributions of labeled and unlabeled molecules. By having both contrasts at hand, the structure of the cell can be imaged in a more complete manner, with the two imaging modalities “informing each other”.
Credit: University of Göttingen, M. Bernhardt et al.

Scientist combines medicine and engineering to repair a damaged heart

Regenerating heart muscle tissue using a 3D printer – once the stuff of Star Trek science fiction – now appears to be firmly in the realm of the possible.

The combination of the Canadian Light Source synchrotron’s unique biomedical imaging and therapy (BMIT) beamline and the vision of a multi-discipline researcher from the University of Saskatchewan in confirming fiction as fact was published in the September issue of Tissue Engineering, one of the leading journals in this emerging global research field of tissue regeneration.

U of S researcher Mohammad Izadifar says he is combining medicine and engineering to develop ways to repair a damaged heart. “The problem is the heart cannot repair itself once it is damaged due to a heart attack.” he explained.

Izadifar has conducted his research out of three places on campus – the College of Engineering, the CLS and the College of Medicine where he has been certified in doing open heart surgery on rats, having trained in all the ethical protocols related to these research animals.