On-chip non-invasive and label-free cell discrimination by impedance spectroscopy

OBJECTIVES: Many flow-cytometric cell characterization methods require costly markers and colour reagents. We present here a novel device for cell discrimination based on impedance measurement of electrical cell properties in a microfluidic chip, without the need of extensive sample preparation steps and the requirement of labelling dyes. MATERIALS AND METHODS, RESULTS: We demonstrate that in-flow single cell measurements in our microchip allow for discrimination of various cell line types, such as undifferentiated mouse fibroblasts 3T3-L1 and adipocytes on the one hand, or human monocytes and in vitro differentiated dendritic cells and macrophages on the other hand. In addition, viability and apoptosis analyses were carried out successfully for Jurkat cell models. Studies on several species, including bacteria or fungi, demonstrate not only the capability to enumerate these cells, but also show that even other microbiological life cycle phases can be visualized. CONCLUSIONS: These results underline the potential of impedance spectroscopy flow cytometry as a valuable complement to other known cytometers and cell detection systems.

Primary pelvic pyomyositis in a neonate

Primary pyomyositis is a bacterial infection occurring in skeletal muscle with no obvious local or adjacent cause. It is classically an infection of the tropics, although it is reported in temperate climates with increasing frequency. Tropical pyomyositis occurs predominantly in children aged between 2 and 5 and in adults aged between 20 and 45 years, whereas most temperate pyomyositis cases occur in adults. Using a magnetic resonance imaging scan, we made the diagnosis of staphylococcal pelvic pyomyositis in a Swiss term-born infant with an initial working diagnosis of septic hip osteoarthritis.