Microchannel Acoustophoresis does not Impact Survival or Function of Microglia, Leukocytes or Tumor Cells

Abstract

BackgroundThe use of acoustic forces to manipulate particles or cells at the microfluidic scale (i.e. acoustophoresis), enables non-contact, label-free separation based on intrinsic cell properties such as size, density and compressibility. Acoustophoresis holds great promise as a cell separation technique in several research and clinical areas. However, it has been suggested that the force acting upon cells undergoing acoustophoresis may impact cell viability, proliferation or cell function via subtle phenotypic changes. If this were the case, it would suggest that the acoustophoresis method would be a less useful tool for many cell analysis applications as well as for cell therapy.MethodsWe investigate, for the first time, several key aspects of cellular changes following acoustophoretic processing. We used two settings of ultrasonic actuation, one that is used for cell sorting (10 Vpp operating voltage) and one that is close to the maximum of what the system can generate (20 Vpp). We used microglial cells and assessed cell viability and proliferation, as well as the inflammatory response that is indicative of more subtle changes in cellular phenotype. Furthermore, we adapted a similar methodology to monitor the response of human prostate cancer cells to acoustophoretic processing. Lastly, we analyzed the respiratory properties of human leukocytes and thrombocytes to explore if acoustophoretic processing has adverse effects.ResultsBV2 microglia were unaltered after acoustophoretic processing as measured by apoptosis and cell turnover assays as well as inflammatory cytokine response up to 48 h following acoustophoresis. Similarly, we found that acoustophoretic processing neither affected the cell viability of prostate cancer cells nor altered their prostate-specific antigen secretion following androgen receptor activation. Finally, human thrombocytes and leukocytes displayed unaltered mitochondrial respiratory function and integrity after acoustophoretic processing.ConclusionWe conclude that microchannel acoustophoresis can be used for effective continuous flow-based cell separation without affecting cell viability, proliferation, mitochondrial respiration or inflammatory status.

Focusing of sub-micrometer particles and bacteria enabled by two-dimensional acoustophoresis

“…The method involves the use of ultrasound standing waves to focus cells or particles in the nodal (or anti-nodal) plane of the standing wave according to their intrinsic properties: size, density, and compressibility. 17 Furthermore, this label-free and gentle 18,19 method-which operates independently of the biochemical and electrical properties of the suspension medium-has been extensively explored to separate, wash, or concentrate various biological…”

Microfluidic bio-particle manipulation for biotechnology

“…Utilizing this idea, red blood cells (RBCs) and platelets have been separated successfully [61]. Although, no bio-particle preparation (other than dilution) and labeling is necessary for acoustic manipulation, labeling of particles were utilized to have better selectivity in a very limited number of studies where bio-particles were tagged with beads which have negative acoustic contrast factors [62]. This way when the acoustic field was employed, the labeled bio-particles can move in the opposite direction of the remaining particles.…”

Ultrasound-Induced Cell–Cell Interaction Studies in a Multi-Well Microplate

“…Several studies have been performed where different cell types and cell functions have been investigated after short-term ultrasound (seconds to minutes). For example, Augustsson et al [39] and Burguillos et al [40] used the XTT assay for measuring the mitochondrial dehydrogenase activity present in cells from prostate cancer cells and BV2 microglial cells, respectively. In another study, Bazou et al [41] performed different biochemical assays on HEP-G2 liver cell aggregates (e.g., detection of hypoxia, cytokeratin-18, glucose and lactate).…”