M.Sc Thesis

M.Sc StudentReichenberg Yaniv
SubjectDevelopment of an Integrated Experimental system for
Real-Time Study of Blood Flow Effects on Cultured
Endothelial cells
DepartmentDepartment of Biomedical Engineering
Supervisor PROFESSOR EMERITUS Yoram Lanir
Full Thesis textFull thesis text - English Version


This study reports on the development and validation of an integrated experimental system for quantitative monitoring of the effects of hemodynamic forces on endothelial cells (ECs), in terms of their morphological remodeling and rheological properties. The system consists of a microscope-based flow bio-reactor which imposes controlled pressure, flow and wall stretch, individually and combined, on ECs cultured on the inner surface of transparent cylindrical substrate tubes. ECs morphology is monitored by optical microscopy. ECs rheological alterations were measured by optical magnetic twisting cytometry (OMTC) using ferromagnetic micro-beads adherent to the ECs cytoskeleton and subjected to externally applied magnetic field. System validation tests ascertained the capability of imposing controlled flow conditions and for real-time monitoring of morphological and rheological changes.

Our ongoing investigation of endothelial cells rheology using optical magnetic twisting cytometry revealed that with time following incubation of the ferromagnetic beads on the cells, beads were sinking into the cells and increasing number of beads demonstrated apparent physically absurd negative rheological properties. In parallel, the beads averaged rheological response changed considerably over time, both in value and in distribution. It was hypothesized that the apparent negative rheological response was related to the above sinking process of seeded beads into the cells, resulting in elevation of the beads’ rotation axis, thus causing a reversal of the beads lateral movement direction. The study results suggest that OMTC-based micro-rheological characterization should be standardized and interpreted with caution while considering the time of data acquisition.