[Possibilities of flow cytometry application for assessment of endothelial dysfunction in cardiac surgery]

Microcirculation disorders are common in cardiac surgery patients who underwent cardiopulmonary bypass (CPB). The impact of various damaging factors and microcirculation disorders cause structural changes in the endothelium, disrupting its cellular interactions and functions. The level of circulating endothelial cells (CECs) in the blood, determined by flow cytometry, can act as a direct cellular marker of endothelial damage and microcirculatory disorders.

To assess the possibility of flow cytometry application in order to determine circulating endothelial cells in cardiac surgery patients who were operated on CPB.

Blood samples of 9 cardiac surgery patients operated on CPB were investigated by flow cytometry in two replicates at 3 stages: before starting surgery, immediately after surgery and 6 hours after surgery. Using ModelFlower software, (2-4)·10⁶ events per sample were collected and analyzed. CECs were defined as CD45dim CD34+CD31+CD146+CD133- among peripheral blood leukocytes.

The level of CECs (n=9) in the peripheral blood amounted to 0.0046 [0.0020; 0.0171] % before surgery, 0.0052 [0.0020; 0.0220] % immediately after surgery and 0.0051 [0.0024-0.0184] % 6 hours after surgery (p>0.05). The absolute count of CECs in the peripheral blood was 153.5 [109.13; 247.38] c/ml before surgery. After surgery, a tendency to increase in the absolute count of CECs has been observed: 360.5 [166.5; 1228.5] c/ml - immediately after and 339 [241.38; 1033.13] c/ml - 6 hours after the surgery. Statistically significant differences were not found (p>0.05), which is most likely due to the small sample size.

Determination of the circulating endothelial cell level has demonstrated a tendency to increase after surgery, which may correspond to the degree of damage to the endothelium after surgery performed on CPB.