Stiffness Dependent Separation of Cells in a Microfluidic Device

Abstract

Abnormal cell mechanical stiffness can point to the development of various diseases including cancers and infections. We report a new microfluidic technique for continuous cell separation utilizing variation in cell stiffness. We use a microfluidic channel decorated by periodic diagonal ridges that compress the flowing cells in rapid succession. The compression in combination with secondary flows in the ridged microfluidic channel translates each cell perpendicular to the channel axis in proportion to its stiffness. We demonstrate the physical principle of the cell sorting mechanism and show that our microfluidic approach can be effectively used to separate a variety of cell types which are similar in size but of different stiffnesses, spanning a range from 210 Pa to 23 kPa. Atomic force microscopy is used to directly measure the stiffness of the separated cells and we found that the trajectories in the microchannel correlated to stiffness. We have demonstrated that the current processing throughput is 250 cells per second. This microfluidic separation technique opens new ways for conducting rapid and low-cost cell analysis and disease diagnostics through biophysical markers.

Microconstriction Arrays for High-Throughput Quantitative Measurements of Cell Mechanical Properties

“…AFM measurements of cells trapped in microwells gave stiffness values at~50 Pa (11). Another AFM study of cells immobilized on a poly-L-lysine-coated glass surface reported a stiffness of 400 Pa (49). Moreover, this study also measured cells after cytochalasin D treatment and reported a 50% decrease in cell stiffness, which is in agreement with our findings.…”

Cellular Stiffness as a Novel Stemness Marker in the Corneal Limbus

“…Previous results further support the relationship between adherent-cell AFM and microfluidic sorting ability: mechanics data from adhered cells correlate with sorting trajectories within our device, and cells taken from the outlets of our device display distinct mechanical properties after attachment (34). Specifically, the relatively soft and low-viscosity K562 cells have been efficiently sorted from HL60 cells (sorting DOR ¼ 205 (36)) and leukocytes (sorting To quantitatively elucidate the relationship between the adherent-cell Young's modulus-based DOR and sorting ability, a meta-analysis of previously published data was conducted (Figs.…”

“…Whereas measuring cellular mechanical properties by AFM is a low-throughput process (~3 min/cell), microfluidics promises to provide a high-throughput method that combines stiffness-, size-, and viscoelasticity-based sorting to isolate stem-like cells (34)(35)(36)(54)(55)(56). Such high-throughput techniques can be used to generate corneal tissue implants with highly enriched stem-like limbal cell populations, which may yield superior clinical outcomes compared with tissue implants that are directly harvested from the cornea (8).…”

A scalable label-free approach to separate human pluripotent cells from differentiated derivatives

“…Recently, we suggested that stiffness could also serve as the basis of a simple and efficient purification technique to discriminate subpopulations of hESC (Kiss et al, 2011). Using AFM, we and others have previously demonstrated effective measurements of cell stiffness for a variety of cell types, including human embryonic (Kiss et al, 2011), mouse embryonic (Pillarisetti et al, 2011), and adult mesenchymal stem cells (Bongiorno et al, 2014), and a variety of human cell lines (Wang et al, 2013), and we applied this tool in our current study as well. We defined cell stiffness as CEM, which varies depending on the cell's function, fate, and lineage commitment.…”

“…Reports describing separation of various cell types based on their stiffness have been produced mainly in the fields of infectious diseases and cancer research and diagnostics. For example, recent papers describe microfluidics methods to separate healthy red blood cells from diseased ones (e.g., sickle cell anaemia (Kose et al, 2009) and malaria infection ), and benign from cancerous cells (e.g., breast cancer (Hou et al, 2009), circulating tumour cells from blood (Hur et al, 2011), and epithelial cancer cells mixed with white blood cells (Wang et al, 2013)). Recently, we suggested that stiffness could also serve as the basis of a simple and efficient purification technique to discriminate subpopulations of hESC (Kiss et al, 2011).…”