Murali Anirudh, Sarkar Ram Rup
Biomicrofluidics. 2024 Oct 21;18(5):054112. doi: 10.1063/5.0216617. eCollection 2024 Sep.
In recent years, the allure of space exploration and human spaceflight has surged, yet the effects of microgravity on the human body remain a significant concern. Immune and red blood cells rely on hematic or lymphatic streams as their primary means of transportation, posing notable challenges under microgravity conditions. This study sheds light on the intricate dynamics of cell behavior when suspended in bio-fluid under varying gravitational forces. Utilizing the dissipative particle dynamics approach, blood and white blood cells were modeled, with gravity applied as an external force along the vertical axis, ranging from 0 to 2 g in parameter sweeps. The results revealed discernible alterations in the cell shape and spatial alignment in response to gravity, quantified through metrics such as elongation and deformation indices, pitch angle, and normalized center of mass. Statistical analysis using the Mann-Whitney U test underscored clear distinctions between microgravity (<1 g) and hypergravity (>1 g) samples compared to normal gravity (1 g). Furthermore, the examination of forces exerted on the solid, including drag, shear stress, and solid forces, unveiled a reduction in the magnitude as the gravitational force increased. Additional analysis through dimensionless numbers unveiled the dominance of capillary and gravitational forces, which impacted cell velocity, leading to closer proximity to the wall and heightened viscous interaction with surrounding fluid particles. These interactions prompted shape alterations and reduced white blood cell area while increasing red blood cells. This study represents an effort in comprehending the effects of gravity on blood cells, offering insights into the intricate interplay between cellular dynamics and gravitational forces.
近年来，太空探索和载人航天的吸引力激增，但微重力对人体的影响仍然是一个重大问题。免疫细胞和红细胞依赖血液或淋巴流动作为其主要运输方式，在微重力条件下带来了显著挑战。本研究揭示了细胞在不同重力作用下悬浮于生物流体中时复杂的行为动态。利用耗散粒子动力学方法，对血液和白细胞进行建模，在参数扫描中沿垂直轴将重力作为外力施加，范围从0到2g。结果显示，通过伸长率、变形指数、俯仰角和归一化质心等指标量化，细胞形状和空间排列因重力而发生明显变化。使用曼-惠特尼U检验的统计分析强调，与正常重力（1g）相比，微重力（<1g）和超重力（>1g）样本之间存在明显差异。此外，对作用于固体的力（包括阻力、剪切应力和固体力）的研究表明，随着重力增加，力的大小会减小。通过无量纲数进行的额外分析揭示了毛细管力和重力的主导作用，它们影响细胞速度，导致细胞更靠近壁面，并增强了与周围流体颗粒的粘性相互作用。这些相互作用促使细胞形状改变，白细胞面积减小，而红细胞面积增加。这项研究是为了理解重力对血细胞的影响，为细胞动力学和重力之间的复杂相互作用提供了见解。
