Leukocyte deformability is a novel biomarker to reflect sepsis-induced disseminated intravascular coagulation

The influence of cell elastic modulus on inertial positions in Poiseuille microflows

Microchannels are used as a transportation highway for suspended cells both in vivo and ex vivo. Lymphatic and cardiovascular systems transfer suspended cells through microchannels within the body, and microfluidic techniques such as lab-on-a-chip devices, flow cytometry, and CAR T-cell therapy utilize microchannels of similar sizes to analyze or separate suspended cells ex vivo. Understanding the forces that cells are subject to while traveling through these channels are important because certain applications exploit these cell properties for cell separation. This study investigated the influence that cytoskeletal impairment has on the inertial positions of circulating cells in laminar pipe flow. Two representative cancer cell lines were treated using cytochalasin D, and their inertial positions were investigated using particle streak imaging and compared between benign and metastatic cell lines. This resulted in a shift in inertial positions between benign and metastatic as well as treated and untreated cells. To determine and quantify the physical changes in the cells that resulted in this migration, staining and nanoindentation techniques were then used to determine the cells' size, circularity, and elastic modulus. It was found that the cells' exposure to cytochalasin D resulted in decreased elastic moduli of cells, with benign and metastatic cells showing decreases of 135 ± 91 and 130 ± 60 Pa, respectively, with no change in either size or shape. This caused benign, stiffer cancer cells to be more evenly distributed across the channel width than metastatic, deformable cancer cells; additionally, a decrease in the elastic moduli of both cell lines resulted in increased migration toward the channel center. These results indicate that the elastic modulus may play more of a part in the inertial migration of such cells than previously thought.

The mechanical responses of advecting cells in confined flow

Fluid dynamics have long influenced cells in suspension. Red blood cells and white blood cells are advected through biological microchannels in both the cardiovascular and lymphatic systems and, as a result, are subject to a wide variety of complex fluidic forces as they pass through. In vivo, microfluidic forces influence different biological processes such as the spreading of infection, cancer metastasis, and cell viability, highlighting the importance of fluid dynamics in the blood and lymphatic vessels. This suggests that in vitro devices carrying cell suspensions may influence the viability and functionality of cells. Lab-on-a-chip, flow cytometry, and cell therapies involve cell suspensions flowing through microchannels of approximately 100-800  μ m. This review begins by examining the current fundamental theories and techniques behind the fluidic forces and inertial focusing acting on cells in suspension, before exploring studies that have investigated how these fluidic forces affect the reactions of suspended cells. In light of these studies' findings, both in vivo and in vitro fluidic cell microenvironments shall also be discussed before concluding with recommendations for the field.