APPlications with rt-dc

Quality control of blood products

Cell types: platelets, red blood cells, stem cells

Outcome:  Using an AcCellerator system with FluorescenceModule the authors in this study approached the question of how cellular blood products like platelet concentrates, red blood cells and hematopoietic stem cells can be assessed label-free and from minimal sample volume. The authors demonstrate the application of RT-DC as a robust quality control tool to monitor the status of platelets stored at different temperature and to verify intracellular changes by nanoparticle exposition. Further, they use mechanical phenotyping to emphasize the  impact of plasticizers in PVC blood bags on the rheology of red blood cells. Finally, they investigated the impact of cryoprotectants on the mechanical properties of hematopoietic stem cells. In summary the study shows that real-time deformability cytometry can be used as a label-free diagnostics with high innovative potential.
(This image has been designed using resources from Freepik.com)

Translational medicine – label-free characterization of suspended cardiomyocytes

Cell types: Cardiomyocytes, Human-induced pluripotent stem cells

Outcome: Human-induced pluripotent stem cells (hiPSC) gain more and more interest in fundamental and translational research. Especially regenerative medicine considers these cells as a source to replace tissues, e.g., after accidents. In a work by Pires et al. the researchers explored the potential of RT-DC to characterize hiPSC-derived cardiomyocytes, which form an important cell type of the heart. The researchers could show that high-throughput mechanical characterization is capable to monitor subtle changes in the structure of these cells. Utilizing these results might allow to label-free assess these cells before transplantation and without the need of fluorescent markers.

Discern blood cell types

Cell types: whole blood  (thrombo-, lympho-, mono-. erythrocytes, baso-, eosino-, neutrophils)

Outcome: Many cell types are distinguishable by properties of their images like brightness and size. In whole blood samples, this enables the identification and further analysis of erythrocytes (red blood cells), thrombocytes (platelets) and even subpopulations of leukocytes (white blood cells) without the need of labeling or cell purification.

Resolve kinetics in neutrophil activation

Cell types: neutrophils

Outcome: High measurement rates and fast sample preparation allow for observation of kinetic processes. The plot below shows the change of mechanical properties when neutrophil granulocytes from freshly drawn blood are exposed to formyl-methionyl-leucyl-phenylalanin (fMLP). The tripeptide fMLP is released by many bacteria and signals an infection to cells of the immune system.

Parasite detection

Cell types: red blood cells

Outcome:  Using the AcCellerator system, we approached the question if the infiltration of the malaria parasite inside red blood cells (RBCs) can be detected based on mechanical cell changes. After in-vitro infection of RBC samples, cells have been analysed over the parasite life cycle of 48 hours. In a typical sample approximately 8-10% of all cells are infected showing a reduction in deformation compared to an untreated control. Interestingly, also the cells in the infected samples that are not exposed to the parasite show a reduction in deformation. This suggests a bystander effect.

In addition, we took advantage of the feature of the AcCellerator system to acquire bright-field images of each single cell. The study demonstrates that our software is capable to identify the parasite directly inside the cell. This suggests the possibility of parasite detection directly from an image analysis. A process, which can be carried out in seconds.

See also:

Plasmodium falciparum erythrocyte-binding antigen 175 triggers a biophysical change in the red blood cell that facilitates invasion

Characterization of artificial red blood cells

Cell types: Red blood cells

The production of therapeutic red blood cells (RBCs) for blood donation is a highly important research area. One of the major challenges is the discrimination between nucleated and enucleated RBCs. The latter still contain a cell nucleus and need to be removed from an artificial blood sample before any clinical application. Using the AcCellerator we demonstrated at throughput rates of exceeding 1,000 cells per second that our system can distinguish between both RBC types. In future the combination of our mechanical cell analysis with a label-free sorting strategy will help to produce purified artificial blood samples.

Detect changes of the cytoskeleton

Cell types: HL60

Outcome: Alterations of the cytoskeleton can be quantified through mechanical analysis. The depletion of actin microfilaments by Cytochalasin D results in a higher deformation and therefore, reduced stiffness of HL60 cells. The plot below shows the superposition of treated and untreated cells.

Investigate effects of past conditions

Cell types: hematopoietic stem cell, CD34 positive cells

Outcome: Primary human hematopoietic stem cells (HSCs), are commonly identified by the presence of the transmembrane protein CD34. The plot below compares CD34+ cells obtained from bone marrow and CD34+ cells that were mobilized into peripheral blood by the granulocyte colony–stimulating factor (G-CSF). While identical according to their CD34+ classification, HSCs derived from peripheral blood are stiffer than HSCs derived from bone marrow.

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