The Impact of Mechanical Circulatory Support Devices on White Blood Cell Phenotype and Function.

Background: Mechanical circulatory support devices (MCSDs) have gradually become an effective treatment of end-stage heart failure (HF). However, the introduction of foreign surfaces and non-physiological shear stress (NPSS) can cause severe damage to various blood cells, leading to impaired function of immune system and increased risk of complications such as inflammation and thrombosis. The effect of mechanical injury on white blood cell (WBC) has been largely neglected compared to that on red blood cell (RBC) and platelet (PLT).

Method: To better understand the impact of MCSDs on WBCs and emphasize the importance of investigating WBC damage to avoid adverse events during mechanical circulatory support, this review elaborated the induction of WBC phenotypic and functional injury by MCSD-related factors, and the relationship between injury and clinical complications. Furthermore, this article provided a detailed review and comparative analysis of in vitro blood-shearing devices (BSDs) and detection methods used in WBC damage investigation.

Results: NPSS, biomaterials and other related factors can activate WBC, decrease WBC function, and promote the release of pro-inflammatory and pro-thrombotic microparticles, increasing the risk of inflammation and thrombotic complications. The evaluation of WBC damage typically involves measuring cell viability and dysfunction using in vitro BSDs (e.g. concentric cylinder devices) and injury detection methods (e.g. flow cytometry).

Conclusions: WBCs with normal morphology may also experience functional failure due to NPSS from MCSDs, leading to sublethal mechanical cell injury. Therefore, the effect of MCSDs on WBCs can be more comprehensively evaluated by a combination of measuring cell functional capacity and cell counting.