Micro-Flow Visualization of Red Blood Cell-Enhanced Platelet Concentration at Sudden Expansion

• Published in: Annals of biomedical engineering Vol. 36; no. 7; pp. 1130 - 1141
• Main Authors: Zhao, Rui, Marhefka, Joie N., Shu, Fangjun, Hund, Samuel J., Kameneva, Marina V., Antaki, James F.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.07.2008; Springer Nature B.V
• Subjects: Biochemistry; Biological and Medical Physics; Biomedical and Life Sciences; Biomedical Engineering and Bioengineering; Biomedicine; Biophysics; Blood Cells - cytology; Blood Cells - physiology; Blood Platelets - cytology; Blood Platelets - physiology; Cell Culture Techniques - instrumentation; Cell Culture Techniques - methods; Classical Mechanics; Coculture Techniques - instrumentation; Coculture Techniques - methods; Equipment Design; Equipment Failure Analysis; Erythrocytes; Flow Cytometry - instrumentation; Flow Cytometry - methods; Humans; Image Interpretation, Computer-Assisted - instrumentation; Image Interpretation, Computer-Assisted - methods; Microfluidic Analytical Techniques - instrumentation; Microfluidic Analytical Techniques - methods; Microscopy, Fluorescence - instrumentation; Microscopy, Fluorescence - methods; Platelet Activation - physiology; Platelet margination; Red blood cell; Complex microflow; Artificial organs; Flow expansion; Thrombosis
• ISSN: 0090-6964; 1573-9686
• DOI: 10.1007/s10439-008-9494-z

Microscopic steps and crevices are inevitable features within prosthetic blood-contacting devices. This study aimed to elucidate the thrombogenicity of the associated microscopic flow features by studying the transport of fluorescent platelet-sized particles in a suspension of red blood cells (RBCs) flowing through a 100 μm:200 μm sudden expansion. Micro-flow visualization revealed a strong influence of hematocrit upon the path of RBCs and spatial concentration of particles. At all flow rates studied (Re = 8.3–41.7) and hematocrit 20% and lower, RBC streamlines were found to detach from the microchannel wall creating an RBC-depleted zone inside the step that was much larger than the cells themselves. However, the observed distribution of particles was relatively homogeneous. By contrast, the RBC streamlines of samples with hematocrit equal to or greater than 30% more closely followed the contour of the microchannel, yet exhibited enhanced concentration of particles within the corner. The corresponding size of the cell depletion layer was comparable with the size of the cells. This study implies that local platelet concentration in blood within the physiological range of hematocrit can be elevated within the flow separation region of a sudden expansion and implicates the role of RBCs in causing this effect.