Red blood cell fatigue evaluation based on the close-encountering point between extensibility and recoverability

Abstract

Red blood cells (RBC) circulate the human body several hundred thousand times in their life span. Therefore, their deformability is really important, especially when they pass through a local capillary whose diameter can be as narrow as 3 μm. While there have been a number of works discussing the deformability in a simulated capillary such as a microchannel, as far as we examined in the literature, no work focusing on the change of shape after reciprocated mechanical stress has been reported so far. One of the reasons is that there have been no appropriate experimental systems to achieve such a test. This paper presents a new concept of RBC fatigue evaluation. The fatigue state is defined by the time of reciprocated mechanical stress when the extensibility and the recoverability characteristics meet each other. Our challenge is how to construct a system capable of achieving stable and accurate control of RBCs in a microchannel. For this purpose, we newly introduced two fundamental components. One is a robotic pump capable of manipulating a cell in the accuracy of ±0.24 μm in an equilibrium state with a maximum response time of 15 ms. The other is an online high speed camera capable of chasing the position of RBCs with a sampling rate of 1 kHz. By utilizing these components, we could achieve continuous observation of the length of a RBC over a 1000 times reciprocated mechanical stress. Through these experiments, we found that the repeat number that results in the fatigue state has a close correlation with extensibility.

Constriction Channel Based Single-Cell Mechanical Property Characterization

“…Initially, the constriction channel design was used to quantify the mechanical properties of RBCs [23,[27][28][29][30][31][32][33][34][35][36][37][38][39][40]. In 2003, Chiu et al, characterized complex behaviors of Plasmodium falciparum infected RBCs using the constriction channels with sizes at 8, 6, 4, and 2 µm in width [23] (see Figure 1a).…”

“…[47] Meanwhile, the microfluidic constriction channel is used to quantify the cellular entry and transition process through a micro channel with a cross-sectional area smaller than the dimensions of a single cell, enabling high-throughput single-cell mechanical property characterization [23][24][25][26] (see Table 1). This technique was first used to evaluate the mechanical properties of RBCs [23,[27][28][29][30][31][32][33][34][35][36][37][38][39][40], which was then expanded to study the deformability of WBCs [24,41,42] and tumor cells [25,[43][44][45]. Leveraging mechanical modeling of the cellular entry process into the constriction channel, the microfluidic constriction channel design can collect size-independent intrinsic biomechanical markers such as cortical tension or Young's modulus [35,[46][47][48].…”

High Resolution Cell Positioning Based on a Flow Reduction Mechanism for Enhancing Deformability Mapping

“…By changing the position command continuously, we can control the flowing velocity of the target cell. In this section, we evaluate the RBC's extensibility, which is an index of the deformability of the cell [9,[20][21][22]. Figure 6a shows an example of the extensibility evaluation test of the RBC.…”

“…There have been a number of works measuring the cell mechanical characteristics, such as cell mechanical impedance [1][2][3], cell deformability [4][5][6][7] and cell property under reciprocated mechanical stress [8,9], by utilizing a microfluidic chip whose cross-sectional area is close to that of the minimum size of the human blood pipe. The measurement of cell mechanical impedance or cell deformability needs an appropriate actuator for manipulating the cell, as shown in Figure 1a.…”

On-Chip Transportation and Measurement of Mechanical Characteristics of Oocytes in an Open Environment

“…With recent micro-nano processing techniques and microfluidics technologies, on-chip measurements have become a feasible option. However, most research on this topic has involved mechanical stimulation of cells by a fluid force applied in a closed microchannel [14,15]. Because no mechanical sensors are employed, these methods cannot reliably quantify the cell mechanical characteristics.…”