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Updated: Aug 6, 2026
Introducing Shear Stress in the Study of Bacterial Adhesion
Published on: September 2, 2011
Shear stress effects on bacterial adhesion, leukocyte adhesion, and leukocyte oxidative capacity on a
M S Shive1, S M Hasan, J M Anderson
1Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Abstract:
Infection of implanted cardiovascular biomaterials still occurs despite inherent host defense mechanisms. Using a rotating disk system, we investigated Staphylococcus epidermidis and polymorphonuclear leukocyte (PMN) adhesion to a polyetherurethane urea (PEUU-A') under shear stress (0-17.5 dynes/cm2) for time periods up to 6 h. In addition, the superoxide (SO) release capacity of PMNs after transient exposure to PEUU-A' under shear stress was determined. Bacterial adhesion in phosphate-buffered saline (PBS) showed a linear shear dependence, decreasing with increasing shear stress. Overall adhesion in PBS decreased with time. However, bacterial adhesion in 25% human serum was similar for all time points up to 360 min. Adhesion was observed at all shear levels, displaying no shear dependence. In contrast, PMN adhesion demonstrated a strong shear dependence similarly for times up to 240 min, decreasing sharply with increasing shear stress. Although PMNs preexposed to shear stress showed a slightly diminished SO release response compared to fresh cells for all stimuli, it was not statistically significant regardless of the stimulus. We conclude that circulating leukocytes are unable to adhere in regions of high shear which may contain adherent bacteria. In addition, exposure to PEUU-A' and shear stress (in the range 0-18 dynes/cm2) is insufficient to cause a depression in the oxidative response of PMNs.
Insights
Bacterial adhesion to cardiovascular biomaterials decreases with higher shear stress. Polymorphonuclear leukocytes (PMNs) cannot adhere in high shear zones, but their superoxide release function remains unaffected by shear stress exposure.
Area of Science:
- Biomaterials Science
- Infectious Diseases
- Immunology
Background:
- Infection of implanted cardiovascular biomaterials remains a clinical challenge despite host defenses.
- Understanding pathogen and host cell interactions with biomaterials under physiological conditions is crucial.
Purpose of the Study:
- To investigate the adhesion of Staphylococcus epidermidis and polymorphonuclear leukocytes (PMNs) to polyetherurethane urea (PEUU-A') under shear stress.
- To assess the impact of shear stress and PEUU-A' exposure on PMN superoxide release capacity.
Main Methods:
- Utilized a rotating disk system to simulate blood flow conditions (0-17.5 dynes/cm²).
- Quantified bacterial and PMN adhesion to PEUU-A' over time (up to 6 hours).
- Measured superoxide release from PMNs after exposure to PEUU-A' under shear stress.
Main Results:
- Bacterial adhesion decreased linearly with increasing shear stress in phosphate-buffered saline (PBS) but showed no shear dependence in human serum.
- PMN adhesion decreased sharply with increasing shear stress.
- PMN superoxide release was not significantly affected by shear stress or PEUU-A' exposure.
Conclusions:
- High shear stress conditions may limit leukocyte adhesion to biomaterials, potentially allowing bacteria to remain adhered.
- Exposure to PEUU-A' and physiological shear stress does not impair PMN oxidative burst response.
