Examining individual neurons from different perspectives

Correlative imaging of a single neuronal cell opens the door to profound multi-perspective sub-cellular examinations

Scientists combined two nano-imaging techniques that stand at opposite ends of the electromagnetic spectrum to demonstrate the benefits of correlative imaging to examine individual neurons from different perspectives.

To showcase this, they studied the molecular structures of amyloid proteins and investigated the role metal ions may play in the development of Alzheimer’s Disease at a previously never achieved resolution. Their detailed observations at the sub-cellular level underscore the potential of using combined nanospectroscopic tools to deal with uncertainties due to the complex nature of a biological sample.

Alzheimer’s Disease is the most common cause of dementia. Many research groups are working to reveal molecular mechanisms to better understand the process by which the disease evolves. Due to the current lack of effective treatments that could stop or prevent Alzheimer’s Disease, new approaches are necessary to find out how people can age without memory loss.

High-resolution microscopy techniques such as electron microscopy and immunofluorescence microscopy are most often used to detect amyloidogenic protein molecules, often considered key factors in the disease’s evolution. However, these commonly used methods generally lack the sensitivity necessary to depict molecular structures. This is why scientists from Lund University in collaboration with SOLEIL and MAX IV carried out a proof of concept study which showcases that combining two imaging modalities can be used as effective tools to assess structural and chemical information directly within a single cell.

Read more on the MAX IV website

Image: a O-PTIR setup: a pulsed, tunable IR laser is guided onto the sample surface (1). b X-ray fluorescence nanoimaging of individual neuronal cells deposited on Si3N4 (1). c Conceptualization of the data analysis based on superimposed optical, O-PTIR, and S-XRF images.

Researchers discover the origin of calcium in human bones

A study from several Italian institutions and the ALBA Synchrotron suggest crystalline calcium carbonate as a precursor of hydroxyapatite in the process of bone formation. Since hydroxyapatite is a mineral constituting 70% of the mass of bone, these findings may have potential applications in the development of new therapeutic approaches in bone cancer. Thanks to the MISTRAL beamline at ALBA, researchers were able to create a 3D tomogram of human cells and visualize calcium depositions inside them.

Stem cells are “non-specialized” cells that can differentiate (transform) into a specific type of cell with a specific function. To become bone cells, stem cells need to “learn” how to take calcium to form the bones. This is related to biomineralization, a process by which living organisms produce minerals, often to harden or stiffen existing tissues. Calcium is known to be found in bones in the form of hydroxyapatite, which is a naturally occurring mineral form of calcium apatite and represents approximately 70% of the mass of bones.

In human cells, biomineralization culminates with the formation of hydroxyapatite, but the mechanism that explains the origination inside the cell and the propagation of the mineral in the extracellular matrix remains largely unexplained, and its characterization is highly controversial, especially in humans.

An interdisciplinary research team, formed by several Italian institutions and the ALBA Synchrotron, used synchrotron-based techniques to characterize the contents of calcium depositions in human stem cells induced to differentiate towards bone cells (osteoblasts). They compared the results for cells at 4 and 10 days after the osteoblastic induction.

Rad more on the ALBA website

Image: Model of early phases of biomineralization showing the localization and composition evolution of Ca compounds during the early phases of osteogenic differentiation. The figure reports also the spectra of Calcite and hydroxyapatite.