Quantitative assessment of dynamic deformability and adhesion of red blood cells possible

March 1, 2016
This is an artist's illustration of the microfluidic system for probing red blood cell (RBC) dynamic deformability and adhesion from whole SCD patient blood samples. Microfluidic system is composed of a Poly(methyl methacrylate) (PMMA) cover, a double sided adhesive (DSA) layer, and a glass slide base. Microfluidic channels are functionalized with fibronectin, which mimics the microvasculature wall in a closed system and can process whole blood. Adhered sickled RBCs deform in microfluidic channels in response to applied flow shear stress. Credit: Grace Gongaware, Cleveland Institute of Art

A team of researchers from the Case Western Reserve University (CWRU) in Cleveland, OH have developed a versatile microfluidic platform integrated with a cell dimensioning algorithm for quantitative assessment of dynamic deformability and adhesion of RBCs in controlled microphysiological flow. Accurate measurement of RBC deformability and adhesion, which are the two key biophysical factors of vaso-occlusion in SCD, holds great potential as a marker for evaluation of disease progression, gaining insight into disease pathophysiology, and development of novel therapeutics. Although various approaches have been utilized for measurement of deformability and adhesion of RBCs, such as atomic force microscopy and optical tweezers, none of these methods could be conducted at physiological conditions using whole blood in a clinically relevant way. The developed microfluidic system can probe deformation characteristics of RBCs at the single cell level, as well as reflecting microvasculature adhesion response in whole SCD patient blood samples.

"Microfluidic techniques allow incorporation of physiological flow conditions, as well as biologically relevant surfaces in a closed setting, which better mimic the natural physiological environment of the RBCs in blood flow. The microfluidic system developed here has the potential to be used in a high-throughput manner with an integrated automated image processing algorithm for measurement of RBC deformability and adhesion in patients' blood." says Professor Umut Gurkan, Ph.D., of the Case Western Reserve University and Principal Investigator on the paper.

Red blood cells (RBCs) undergo dynamic reversible deformations in blood circulation and respond to fluid shear stresses rapidly with time constants in the range of 100 milliseconds. However, RBCs lose their ability to deform dynamically with maladies such as diabetes, malaria infection, hereditary spherocytosis, and various mutations affecting globin genes, such as the sickle cell disease (SCD). SCD is the first recog-nized molecular disease, which was identified as a hemoglobin disorder more than sixty years ago. In the roots of the disease is a point mutation in the 6th chain of the hemoglobin gene, which results in abnormal polymerization of hemoglobin molecules inside the RBCs. Formation of polymerized hemoglobin fibers disrupts cell morphology, decreases RBC deformability (increase in stiffness), and changes membrane adhesive properties. Abnormal adhesion and decreased deformability of RBCs are the main causes of blood vessel occlusion (vaso-occlusion) in SCD. Vaso-occlusion is the hallmark of the disease and it has been associated with severe pain, crises, wide-spread organ damage, and early mortality.

Molecular basis of the SCD have been investigated extensively. However, there are limited number of studies focusing on the biophysical factors in tandem, such as the deformability and the adhesion of RBCs, which are highly dynamic phenomena. Even though RBC deformability has been associated with vaso-occlusion in SCD, we have limited knowledge on dynamic deformation characteristics of RBCs adhered to endothelium associated proteins in microphysiological fluid flow conditions. While various approaches have been utilized for the measurement of RBC deformability, including optical tweezers, micropipette aspiration, atomic force microscopy (AFM), and microfluidics. Even though optical tweezers, micropipette aspiration, and AFM analyses have enabled sensitive and controlled measurement of RBC mechanical properties, these methods are typically performed in open environments without fluid flow.

The developed microfluidic platform by the CWRU researchers can probe dynamic deformation behavior of adhered RBCs under physiological flow conditions at the single cell level. To assess dynamic deformability of RBCs, the researchers introduced a new parameter: dynamic deformability index (DDI), which they defined as the time dependent change of the cell's aspect ratio. "Using this microfluidic system, we ana-lyzed dynamic deformability and adhesion of sickle RBCs at physiological and above physiological flow shear stresses. We report for the first time on the subpopulations of RBCs in terms of dynamic deformation characteristics in SCD: deformable and non-deformable RBCs. Furthermore, we analyzed adhesion of non-deformable RBCs, in comparison to deformable RBCs, quantitatively at physiological and above physiological flow shear stresses in blood samples obtained from SCD patients. We observed significantly greater number of adhered non-deformable sickle RBCs than deformable sickle RBCs at flow shear stresses well-above the physiological range, suggesting an interplay between dynamic deformability and increased adhesion of RBCs in vaso-occlusive events." says Yunus Alapan, Ph.D. candidate, the lead author on this paper.

A unified investigation of adhesion and deformability properties of RBCs may have significant implications for understanding vaso-occlusion events and for phenotyping disease pathophysiology. Studying dynamic deformation of cells may have implications in other multi-system diseases such as β-thalassemia, diabetes mellitus, hereditary spherocytosis, polycythemia vera, and malaria. The team from CWRU is now working to further characterize deformability and adhesion of RBCs in greater number of SCD patients to analyze their associations with clinical phenotypes and complications. This adaptable technology may give important biophysical insights into disease pathophysiology when widely applied in SCD. Further-more, the developed microfluidic platform has the potential to be used as an in vitro assay for monitoring disease activity, at baseline and during clinical flux after treatment, during painful episodes, and in association with long-term complications.

Explore further: Effect of duration of storage of red blood cells transfused for cardiac surgery

More information: Y. Alapan et al. Dynamic deformability of sickle red blood cells in microphysiological flow, TECHNOLOGY (2016). DOI: 10.1142/S2339547816400045

Related Stories

Effect of duration of storage of red blood cells transfused for cardiac surgery

October 20, 2015
Although some studies have suggested that transfusion of stored red blood cell (RBC) concentrates may be harmful, as blood undergoes several physiological changes during storage, an analysis of patients who underwent cardiac ...

Quantitative measurement of oxygen affinity in a single red blood cell

August 3, 2015
Researchers report a system that quantitatively measures cell volume, hemoglobin mass, and oxygen saturation in individual red blood cells. They found that oxygen affinity is different for individual red blood cells. These ...

AAP still opposes retail-based clinics for pediatric primary care

February 24, 2014
(HealthDay)—The American Academy of Pediatrics (AAP) continues to oppose retail-based clinics (RBCs) as a source of pediatric primary care, according to a policy statement published online Feb. 24 in Pediatrics.

Malaria-infected cells may latch onto healthy blood cells for protection

November 5, 2014
The distinctive 'clumping' of blood cells that blocks vessels and causes tissue damage in malaria-infected patients is the focus of a multinational collaboration, which includes A*STAR researchers.

Protein found to regulate red blood cell size and number

August 28, 2012
The adult human circulatory system contains between 20 and 30 trillion red blood cells (RBCs), the precise size and number of which can vary from person to person. Some people may have fewer, but larger RBCs, while others ...

Recommended for you

Gene therapy improves immunity in babies with 'bubble boy' disease

December 9, 2017
Early evidence suggests that gene therapy developed at St. Jude Children's Research Hospital will lead to broad protection for infants with the devastating immune disorder X-linked severe combined immunodeficiency disorder. ...

In lab research, scientists slow progression of a fatal form of muscular dystrophy

December 8, 2017
In a paper published in the Nature journal Scientific Reports, Saint Louis University (SLU) researchers report that a new drug reduces fibrosis (scarring) and prevents loss of muscle function in an animal model of Duchenne ...

Double-blind study shows HIV vaccine not effective in viral suppression

December 7, 2017
(Medical Xpress)—A large team of researchers from the U.S. and Canada has conducted a randomized double-blind study of the effectiveness of an HIV vaccine and has found it to be ineffective in suppressing the virus. In ...

Time matters: Does our biological clock keep cancer at bay?

December 7, 2017
Our body has an internal biological or "circadian" clock, which cycles daily and is synchronized with solar time. New research done in mice suggests that it can help suppress cancer. The study, publishing 7 December in the ...

Novel harvesting method rapidly produces superior stem cells for transplantation

December 7, 2017
A new method of harvesting stem cells for bone marrow transplantation - developed by a team of investigators from the Massachusetts General Hospital (MGH) Cancer Center and the Harvard Stem Cell Institute - appears to accomplish ...

Inhibiting TOR boosts regenerative potential of adult tissues

December 7, 2017
Adult stem cells replenish dying cells and regenerate damaged tissues throughout our lifetime. We lose many of those stem cells, along with their regenerative capacity, as we age. Working in flies and mice, researchers at ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.