Deformation mechanism of leukocyte adhering to vascular surface under steady shear flow  

作　　者：LIU Xiaoheng1, WANG Xiong2, YIN Hongmei3 & CHEN Huaiqing 1 1. Institute of Biomedical Engineering, Center of West China Medical Sciences, Sichuan University, Chengdu 610041, China 2. LEMTA-UMR-CNRS 7563, Vandoeuvre-les-Nancy, France 3. West China School of Pharmacy, Sichuan University, Chengdu 610041, China 

出　　处：《Science China(Life Sciences)》2004年第2期165-174,共10页中国科学（生命科学英文版）

基　　金：This work was supported by the French Ministry of Research Grant Post-Doc N°271;National Natural Science Foundation of China(Grant No.10102012).

摘　　要：The adhesion of leukocytes to vascular surface is an important biomedical problem and has drawn extensive attention. In this study, we propose a compound drop model to simulate a leukocyte with a nucleus adhering to the surface of blood vessel under steady shear flow. A two-dimensional computational fluid dynamics (CFD) is conducted to determine the local distri- bution of pressure on the surface of the adherent model cell. By introducing the parameter of deformation index (DI), we investigate the deformation of the leukocyte and its nucleus under controlled conditions. Our numerical results show that: (i) the leukocyte is capable of deformation under external exposed flow field. The deformation index increases with initial contact angle and Reynolds number of external exposed flow. (ii) The nucleus deforms with the cell, and the de- formation index of the leukocyte is greater than that of the nucleus. The leukocyte is more de- formable while the nucleus is more capable of resisting external shear flow. (iii) The leukocyte and the nucleus are not able to deform infinitely with the increase of Reynolds number because the deformation index reaches a maximum. (iv) Pressure distribution confirms that there exists a region downstream of the cell, which produces high pressure to retard continuous deformation and provide a positive lift force on the cell. Meanwhile, we have measured the deformation of human leukocytes exposed to shear flow by using a flow chamber system. We found that the numerical results are well consistent with those of experiment. We conclude that the nucleus with high viscosity plays a particular role in leukocyte deformation.The adhesion of leukocytes to vascular surface is an important biomedical problem and has drawn extensive attention. In this study, we propose a compound drop model to simulate a leukocyte with a nucleus adhering to the surface of blood vessel under steady shear flow. A two-dimensional computational fluid dynamics (CFD) is conducted to determine the local distri- bution of pressure on the surface of the adherent model cell. By introducing the parameter of deformation index (DI), we investigate the deformation of the leukocyte and its nucleus under controlled conditions. Our numerical results show that: (i) the leukocyte is capable of deformation under external exposed flow field. The deformation index increases with initial contact angle and Reynolds number of external exposed flow. (ii) The nucleus deforms with the cell, and the de- formation index of the leukocyte is greater than that of the nucleus. The leukocyte is more de- formable while the nucleus is more capable of resisting external shear flow. (iii) The leukocyte and the nucleus are not able to deform infinitely with the increase of Reynolds number because the deformation index reaches a maximum. (iv) Pressure distribution confirms that there exists a region downstream of the cell, which produces high pressure to retard continuous deformation and provide a positive lift force on the cell. Meanwhile, we have measured the deformation of human leukocytes exposed to shear flow by using a flow chamber system. We found that the numerical results are well consistent with those of experiment. We conclude that the nucleus with high viscosity plays a particular role in leukocyte deformation.

关 键 词：leukocyte  deformation  simulation  SHEAR flow  adhesion  biomechanics. 

分 类 号：R543[医药卫生—心血管疾病]