Vasoplegia observed post cardiopulmonary bypass (CPB) is associated with substantial morbidity, multiple organ failure and mortality. Circulating counts of hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPC) are potential markers of neo-vascularization and vascular repair. However, the significance of changes in the circulating levels of these progenitors in perioperative CPB, and their association with post-CPB vasoplegia, are currently unexplored. We enumerated HSC and EPC counts, via flow cytometry, at different time-points during CPB in 19 individuals who underwent elective cardiac surgery. These 19 individuals were categorized into two groups based on severity of post-operative vasoplegia, a clinically insignificant vasoplegic Group 1 (G1) and a clinically significant vasoplegic Group 2 (G2). Differential changes in progenitor cell counts during different stages of surgery were compared across these two groups. Machine-learning classifiers (logistic regression and gradient boosting) were employed to determine if differential changes in progenitor counts could aid the classification of individuals into these groups. Enumerating progenitor cells revealed an early and significant increase in the circulating counts of CD34+ and CD34+CD133+ hematopoietic stem cells (HSC) in G1 individuals, while these counts were attenuated in G2 individuals. Additionally, EPCs (CD34+VEGFR2+) were lower in G2 individuals compared to G1. Gradient boosting outperformed logistic regression in assessing the vasoplegia grouping based on the fold change in circulating CD 34+ levels. Our findings indicate that a lack of early response of CD34+ cells and CD34+CD133+ HSCs might serve as an early marker for development of clinically significant vasoplegia after CPB.

中文翻译：

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体外循环（CPB）相关血管性瘫痪患者循环祖细胞的动力学变化：一项初步研究

体外循环（CPB）后观察到的血管痉挛与大量发病，多器官功能衰竭和死亡率相关。造血干细胞（HSC）和内皮祖细胞（EPC）的循环计数是新血管形成和血管修复的潜在标志。然而，目前尚不清楚围手术期CPB中这些祖细胞循环水平改变的重要性及其与CPB后血管停滞的关系。我们通过流式细胞仪计算了19例行择期心脏手术的患者在CPB期间不同时间点的HSC和EPC计数。根据术后血管痉挛的严重程度，将这19个人分为两组：临床上微不足道的血管痉挛组1（G1）和临床上显着的血管痉挛组2（G2）。在这两组中比较了不同手术阶段祖细胞计数的差异性变化。使用机器学习分类器（逻辑回归和梯度增强）来确定祖细胞计数的差异变化是否可以帮助将个体分类到这些组中。枚举的祖细胞显示G1个体CD34 +和CD34 + CD133 +造血干细胞（HSC）的循环计数早期显着增加，而在G2个体中这些计数减少。此外，与G1相比，G2个体的EPC（CD34 + VEGFR2 +）更低。基于循环CD 34+水平的倍数变化，在评估血管痉挛分组时，梯度增强优于logistic回归。