Choi E S, Hokom M M, Nichol J L, Hornkohl A, Hunt P
AMGEN Center, Thousand Oaks, CA 91320, USA.
C R Acad Sci III. 1995 Mar;318(3):387-93.
A recent report from this laboratory described an in vitro system in which CD34+ cells are stimulated to form mature megakaryocytes and, subsequently, cytoplasmic processes also known as pro-platelets that give rise to functional platelets. Thrombin, an important regulator of hemostasis, has been demonstrated to have an inhibitory role in cytoplasmic process formation from both human and guinea pig megakaryocytes. This inhibition can be reversed by antithrombin III (ATIII), an inhibitor of thrombin, in combination with heparin, a cofactor of ATIII and a glycosaminoglycan. Using the described human in vitro system, the role of thrombin and of glycosaminoglycans are investigated. Thrombin receptors are expressed on megakaryocytes, suggesting that the inhibition by thrombin may be direct. Matrigel, a basement membrane matrix containing glycosaminoglycans, is used to compare the frequency and the rate of cytoplasmic process formation. A possible role of glycosaminoglycans in platelet production is discussed.
该实验室最近的一份报告描述了一种体外系统，在该系统中，CD34+细胞被刺激形成成熟的巨核细胞，随后形成也被称为前血小板的细胞质突起，进而产生功能性血小板。凝血酶是止血的重要调节因子，已被证明对人和豚鼠巨核细胞的细胞质突起形成具有抑制作用。抗凝血酶III（ATIII）是凝血酶的抑制剂，与ATIII的辅因子肝素（一种糖胺聚糖）联合使用时，这种抑制作用可以被逆转。利用所描述的人类体外系统，研究了凝血酶和糖胺聚糖的作用。巨核细胞上表达凝血酶受体，这表明凝血酶的抑制作用可能是直接的。基质胶是一种含有糖胺聚糖的基底膜基质，用于比较细胞质突起形成的频率和速率。文中讨论了糖胺聚糖在血小板生成中的可能作用。
