Description
Background: The introduction of a foreign surface and the shear stress encountered by the blood moving through a rotary pump can affect both cells and proteins with leukocytes shown to be more vulnerable to shear than erythrocytes. At high shear, viability, counts, morphology, and function have been shown to be significantly impaired. As leukocytes link both thrombosis and infection, it is important to observe how they are affected by the VAD environment. Aim: To replicate the artificial shear on a foreign surface introduced to the body by ventricular assist devices (VADs) using biomaterial discs attached to a rheometer. Methods: Biomaterial discs: diamond-like carbon coated stainless steel (DLC); single crystal sapphire (Sap); and titanium alloy (Ti) were attached to parallel plates on a rheometer. Whole human blood was sheared for 5 min between all discs at 0 s-1 and 1000 s-1. Complete blood counts were measured. Flow cytometry was used to measure leukocyte activation (L-selectin and CD11b), phagocytosis, ROS, and viability. ELISA was used to measure cytokines of interest after initial proteome profiling (MIF and IL-1α). Results: Data shown as fold from baseline. Leukocyte counts (n = 6) were reduced when sheared on Sap with neutrophils significantly decreased (69.3 ± 21 %, p = 0.005). Activation of neutrophils and monocytes was evident through a significant decrease in L-selectin on Sap both at 0 s-1 and 1000 s-1 (n = 9, p < 0.05). There was no increase in the expression of CD11b or cell death in any biomaterial/shear combination. The functionality of leukocytes in terms of phagocytosis (n = 3) was decreased when in contact with DLC at 0 s-1 (77.3 ± 9.1%) and delayed when sheared at this surface (70 ± 20.1%). There was no significant difference in IL-1α or MIF production in any samples tested. Conclusions: Initial results correlate with previous work using biomaterials in a static environment with leukocytes, particularly monocytes, affected by Sap when static/sheared. DLC has shown minimal leukocyte activation when static/sheared which may explain the reduction in phagocytic activity. This work may reveal why some pump designs are more susceptible to thrombus formation, particularly at the bearings. Ongoing work involves alternating between shear and no shear on the biomaterials over a short period.| Period | 8 Sept 2017 |
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| Event title | 44th ESAO and 7th IFAO Congress |
| Event type | Conference |
| Location | Vienna, AustriaShow on map |
| Degree of Recognition | International |