Woods M J, Greaves M, Smith G H, Trowbridge E A
Department of Medical Physics, University of Sheffield, Royal Hallamshire Hospital, U.K.
J Thorac Cardiovasc Surg. 1993 Oct;106(4):658-63.
Megakaryocytes with intact cytoplasm normally leave the bone marrow, enter central venous blood, and are filtered in the lungs. During cardiopulmonary bypass, large megakaryocytes are not filtered by the lungs and may not be removed in the extracorporeal circuit by arterial line filters. In such circumstances, they could enter the systemic circulation and block smaller cerebral vessels, resulting in neurologic impairment. To investigate the fate of circulating megakaryocytes during cardiopulmonary bypass, central venous blood and oxygenated blood samples before and after arterial line filtration (40 microns polyester screen filter) were obtained from 10 patients undergoing cardiopulmonary bypass. Megakaryocytes were isolated by whole blood filtration and identified by their characteristic structure after May-Grunwald-Giemsa staining. In preliminary studies, megakaryocyte identification was verified by immunolabeling. All samples contained megakaryocytes with copious cytoplasm. Their frequencies in central venous blood and oxygenated blood before and after the arterial line filtration (corrected for hemodilution) were 23.4 +/- 9.3 per milliliter (mean +/- standard error of the mean, range 3.1 to 89.7 per milliliter), 21.0 +/- 8.2 per milliliter (2.0 to 84.2 per milliliter) and 17.1 +/- 7.4 per milliliter (3.1 to 80.4 per milliliter), respectively. Megakaryocytes with scant or no visible cytoplasm were also observed. The results confirm that circulating megakaryocytes are a normal physiologic component. During cardiopulmonary bypass, megakaryocytes with copious cytoplasm (mean diameter 42.7 microns, range 22 to 78 microns) can pass through the extracorporeal circuit. In the absence of filtration by the lungs, these large cells have access to the systemic circulation. This study supports a possible role for circulating megakaryocytes in the development of cerebral dysfunction after cardiopulmonary bypass.
细胞质完整的巨核细胞通常离开骨髓，进入中心静脉血，并在肺部被过滤。在体外循环期间，大型巨核细胞不会被肺部过滤，并且可能不会被动脉管路过滤器在体外循环中清除。在这种情况下，它们可能进入体循环并阻塞较小的脑血管，导致神经功能损害。为了研究体外循环期间循环巨核细胞的去向，从10例接受体外循环的患者中获取了动脉管路过滤（40微米聚酯筛网过滤器）前后的中心静脉血和氧合血样本。通过全血过滤分离巨核细胞，并在May-Grunwald-Giemsa染色后根据其特征性结构进行鉴定。在初步研究中，通过免疫标记验证了巨核细胞的鉴定。所有样本均含有细胞质丰富的巨核细胞。它们在中心静脉血以及动脉管路过滤前后的氧合血中的频率（校正血液稀释后）分别为每毫升23.4±9.3（平均值±平均标准误差，范围为每毫升3.1至89.7）、每毫升21.0±8.2（2.0至84.2每毫升）和每毫升17.1±7.4（3.1至80.4每毫升）。还观察到细胞质稀少或不可见的巨核细胞。结果证实循环巨核细胞是正常的生理成分。在体外循环期间，细胞质丰富的巨核细胞（平均直径42.7微米，范围为22至78微米）可以通过体外循环。在没有肺部过滤的情况下，这些大细胞可进入体循环。这项研究支持循环巨核细胞在体外循环后脑功能障碍发生中可能起的作用。
