56 / 2019-08-11 21:13:01

Bionic-Capillaries for Research on Deformability and Recoverability of Red Blood Cells

BIONIC CAPILLARY,RED BLOOD CELL,BLOOD STORAGE,ARTIFICIAL CELL

全体主题 > Design and fabrication of biological systems

Bionic-Capillaries for Research on Deformability and Recoverability of Red Blood Cells

Yuanyuan Chen1, Huawei Chen1

1 School of Mechanical Engineering and Automation, Beijing Advanced Innovation Center for Biomedical Engineering, Institute of Bionic and Micro-Nano Systems, Beihang University, Beijing, 100191, China

Contact email address: chenhw75@buaa.edu.cn
Introduction
The global shortage of blood Banks has increased the importance of blood storage and research into artificial red blood cells1. Medical and biological research have given some results to prove how better to store blood2. Materials scientists and chemists have done a lot of studies on artificial red blood cells (RBCs)3. While, during circulation in blood vessels, RBCs experience a series of mechanical deformation, therefore, it is necessary to explore the characteristics of RBCs from mechanical angle, which could offer some benign advice for blood storage and artificial RBCs. Allowing for the circulation in blood capillaries, this research manufactured two types of bionic capillaries to investigate the deformability and recoverability of RBCs.
Materials and methods
RBCs preparation: Blood were taken from the finger of healthy volunteer, after washing, RBCs were re-suspended in phosphate-buffered saline (PBS) buffer with concentration of 0.2%v/v. CaCl2 was added into PBS solution with a guaranteed concentration of 2mM.
Set up: The motions of RBCs were captured by a fast camera (V710, Phantom Co.) under an inverted microscope (LEICA DME6000 B). And all the values of cell length were obtained by Image J from the captured videos.
Microchannel: The microchannels were fabricated using the standard polydimethylsiloxane (PDMS) lithographic method. As shown in Fig1.a, the channel is a single layer with height of 5μm, and the squeezing width (W) is 5μm. There are two squeezing channels, L1=3W, and L2=300W.
Results
The deformability and recoverability of single RBC were represented by L1 and L2, as defined and measured in the Fig1.b-c, and Ln=200μm. Three independent experiments were repeated, and 100 cells were counted in each experiment. According to Fig1. b1, the elongation of the cell decreased with the increase of squeezing, from 10μm to less than 8μm in L=3W channel. Moreover, slightly lower elongations were observed in the solution with Ca2+, indicating that the deformability of RBCs was reduced. According to Fig1. b2, cell recovery length L2, after the short-repeated squeezing, decreased as the squeezing number increased, from 8.2μm to 7μm. In addition, slightly lower cell recovery length was observed in the solution with Ca2+, indicating that the presence of Ca2+ might reduce cell size. According to Fig1. c1-c2, the variation of L1 and L2 along squeezing number and existing of Ca2+ were also the same variation with L1=3W channel, while, the initial value of L1 and L2 changed. L1 changed from 11μm down to 9μm, and L2 changed from 8.4μm down to 8.1μm.

Figure 1. Effect of two bionic capillaries on cell fatigue.
Conclusions
From the mentioned results, it could be concluded that long squeezing could increase the value of L1, further enhanced cell deformation, and the high value and low change of L2 meant that long squeezing generated high impairment on cell membrane, further decreased cell recoverability. In other word, under long squeezing condition, RBCs were easy to more prone to be fatigue.
References
[1] Marilynn C. et al. TRANSFUSION 2019, 59(1259).
[2] Ranucci M. et al. Critical Care, 2009, 13(6).
[3] Bialas C. et al. The journal of trauma and acute care surgery, 2019, 87(S48-S58).