Blood contact with artificial surfaces during BVAD support

The study aimed to evaluate how blood interacts with artificial surfaces commonly used in ventricular assist devices. Specifically, the researchers wanted to determine if these interactions contribute to the chronic inflammatory response observed in patients. They focused on two materials: silicone and polyurethane. These materials are frequently used in the construction of ventricular assist systems. The study tested whether these materials stimulate immune cells to release inflammatory mediators. The motivation was to assess whether in vitro effects of these materials correlate with in vivo cytokine levels. The researchers also sought to determine if coating surfaces with protein could mitigate these effects. The ultimate goal was to clarify whether blood/surface interactions are a significant source of inflammation during mechanical circulatory support.

The researchers used in vitro experiments to assess the biocompatibility of silicone and polyurethane membranes. They incubated isolated mononuclear cells or whole blood in tubes coated with either material for 24 hours. The study measured concentrations of various inflammatory mediators in the supernatant. The experimental setup included control groups with uncoated tubes. Both silicone and polyurethane were tested for their effects on monocytes and thrombocytes. The study also examined complement activation triggered by contact with artificial surfaces. The researchers tested whether protein-coated surfaces could reduce the observed effects. The methods involved measuring specific cytokines like IL-8, MIP-1 alpha, P-Selectin, and PDGF-AB.

Monocytes were stimulated to release inflammatory cytokines, particularly IL-8 and MIP-1 alpha, when exposed to silicone. Both silicone and polyurethane surfaces activated thrombocytes, leading to the release of P-Selectin and PDGF-AB. However, polyurethane was a stronger stimulus for thrombocyte activation than silicone. Moderate complement activation was observed with both materials. The effects of these materials were largely prevented when surfaces were coated with protein. The study found no correlation between in vitro cytokine levels and serum cytokine levels in patients receiving circulatory support. These findings suggest that blood/surface interactions may not be the primary cause of persistent cytokine elevation. The lack of correlation implies that other factors may be driving the inflammatory response in vivo.

The authors concluded that blood/surface interactions do not appear to be the main cause of persistent cytokine elevation in patients receiving ventricular assist devices. The study found that in vitro effects of silicone and polyurethane were mitigated by protein coatings. The lack of correlation between in vitro and in vivo cytokine levels suggests that other mechanisms may be responsible for the observed inflammation. The findings indicate that the chronic inflammatory process during mechanical circulatory support is not primarily driven by artificial surfaces. The researchers propose that systemic factors may play a larger role in sustaining cytokine levels. The study highlights the importance of distinguishing between device-induced and systemic inflammatory responses. These conclusions are based on the observed lack of correlation between in vitro and in vivo data. The results suggest that future research should focus on identifying alternative sources of inflammation in these patients.