title: Biomechanics of red blood cells in human spleen and consequences for physiology and disease.
abstract: Red blood cells (RBCs) can be cleared from circulation when alterations in their size, shape, and deformability are detected. This function is modulated by the spleen-specific structure of the interendothelial slit (IES). Here, we present a unique physiological framework for development of prognostic markers in RBC diseases by quantifying biophysical limits for RBCs to pass through the IES, using computational simulations based on dissipative particle dynamics. The results show that the spleen selects RBCs for continued circulation based on their geometry, consistent with prior in vivo observations. A companion analysis provides critical bounds relating surface area and volume for healthy RBCs beyond which the RBCs fail the "physical fitness test" to pass through the IES, supporting independent experiments. Our results suggest that the spleen plays an important role in determining distributions of size and shape of healthy RBCs. Because mechanical retention of infected RBC impacts malaria pathogenesis, we studied key biophysical parameters for RBCs infected with Plasmodium falciparum as they cross the IES. In agreement with experimental results, surface area loss of an infected RBC is found to be a more important determinant of splenic retention than its membrane stiffness. The simulations provide insights into the effects of pressure gradient across the IES on RBC retention. By providing quantitative biophysical limits for RBCs to pass through the IES, the narrowest circulatory bottleneck in the spleen, our results offer a broad approach for developing quantitative markers for diseases such as hereditary spherocytosis, thalassemia, and malaria.
authors.affiliation: Institute of Computational Science, Faculty of Informatics, University of Lugano, 6900 Lugano, Switzerland; Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland;
authors.forename: Igor V
authors.initials: IV
authors.lastname: Pivkin
authors.affiliation: Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556; Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139;
authors.forename: Zhangli
authors.initials: Z
authors.lastname: Peng
authors.affiliation: Division of Applied Mathematics, Brown University, Providence, RI 02912;
authors.forename: George E
authors.initials: GE
authors.lastname: Karniadakis
authors.affiliation: Faculté de Médecine Université Paris Descartes, Institut National de la Transfusion Sanguine, 75015 Paris, France; Laboratoire d'Excellence GR-Ex, F-75015 Paris, France;
authors.forename: Pierre A
authors.initials: PA
authors.lastname: Buffet
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; mingdao@mit.edu suresh@cmu.edu.
authors.forename: Ming
authors.initials: M
authors.lastname: Dao
authors.affiliation: Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA 15213; Computational Biology Department, Carnegie Mellon University, Pittsburgh, PA 15213; Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 mingdao@mit.edu suresh@cmu.edu.
authors.forename: Subra
authors.initials: S
authors.lastname: Suresh
mesh_terms: D001696:Biomechanical Phenomena; D003198:Computer Simulation; D004912:Erythrocytes / Q000166:cytology*; D006801:Humans; D008962:Models, Theoretical; D010963:Plasmodium falciparum; D013154:Spleen / Q000502:physiology*
keywords: erythrocytes; malaria; microcirculation; spherocytosis; spleen clearance