Washing or filtering of blood products does not improve outcome in a rat model of trauma and multiple transfusion

Abstract

Background: Transfusion is associated with organ failure and nosocomial infection in trauma patients, which may be mediated by soluble bioactive substances in blood products, including extracellular vesicles (EVs). We hypothesize that removing EVs, by washing or filtering of blood products, reduces organ failure and improves host immune response.

Materials and methods: Blood products were prepared from syngeneic rat blood. EVs were removed from RBCs and platelets by washing. Plasma was filtered through a 0.22-μm filter. Rats were traumatized by crush injury to the intestines and liver, and a femur was fractured. Rats were hemorrhaged until a mean arterial pressure of 40 mm Hg and randomized to receive resuscitation with standard or washed/filtered blood products, in a 1:1:1 ratio. Sham controls were not resuscitated. Ex vivo whole blood stimulation tests were performed and histopathology was done.

Results: Washing of blood products improved quality metrics compared to standard products. Also, EV levels reduced by 12% to 77%. The coagulation status, as assessed by thromboelastometry, was deranged in both groups and normalized during transfusion, without significant differences. Use of washed/filtered products did not reduce organ failure, as assessed by histopathologic score and biochemical measurements. Immune response ex vivo was decreased following transfusion compared to sham but did not differ between transfusion groups.

Conclusion: Filtering or washing of blood products improved biochemical properties and reduced EV counts, while maintaining coagulation abilities. However, in this trauma and transfusion model, the use of optimized blood components did not attenuate organ injury or immune suppression.

Figure 1

Parameters of shock in different treatment groups over time. (A) Blood lactate levels expressed as medians. (B) Blood glucose levels expressed as medians. (C) Base deficit levels expressed as medians. (D) Blood pH levels expressed as means. (E) Hemoglobin levels in g/dL expressed as means. (F) Mean arterial pressure in mm Hg expressed as means. (G) Timeline of the experiment. Every hour blood samples were collected for biochemical analysis, blood gas analysis, and ROTEM. WBS = whole blood stimulations. * = p < 0.05.

Figure 2

Coagulation parameters over time as measured by rotation thromboelastometry. Values are presented as median values. (A) Clotting time (CT) measured in seconds (dotted lines are reference values*: 38–79 seconds). (B) Maximum clot firmness (MCF) measured in mm (dotted lines are reference values*: 50–72 mm). (C) α‐angle measured in degrees (dotted lines are reference values*: 61–83 degrees). (D) G‐value measured in dynes/cm2 (dotted lines are reference values*: 5–11.7 dynes/cm2).4 * = Based on human reference values.

Figure 3

Histopathologic examination of organ injury. (A) Organ injury score based on histopathologic examination, presented as median and interquartile ranges. (B) Representative microphotographs of lung tissue (magnification 100×). [Color figure can be viewed at wileyonlinelibrary.com]

Figure 4

Markers of organ injury over time. Values are given in median and interquartile ranges. (A) AST levels measured in arterial blood samples (p value determined by Mann‐Whitney U test). (B) Creatinine levels measured in arterial blood samples. (C) ALT levels measured in arterial blood samples. (D) Lactate dehydrogenase (LDH) levels measured in arterial blood samples.* = p < 0.05.

Figure 5

Cytokine levels in plasma over time and in lungs at sacrifice. (A) Plasma IL‐6 levels over time in the different groups. (B) IL‐6 levels in bronchoalveolar lavage fluid taken at exsanguination in the different groups. Values are given in median and interquartile ranges.

Figure 6

Whole blood stimulations with LPS in different treatment groups. Cytokine levels after whole blood stimulation of samples taken at exsanguination and stimulated with LPS. Values are given in mean and standard deviation.