Wysoczynski Marcin, Reca Ryan, Ratajczak Janina, Kucia Magda, Shirvaikar Neeta, Honczarenko Marek, Mills Michael, Wanzeck Jens, Janowska-Wieczorek Anna, Ratajczak Mariusz Z
Stem Cell Biology Program, James Graham Brown Cancer Center, University of Louisville, KY 40202, USA.
Blood. 2005 Jan 1;105(1):40-8. doi: 10.1182/blood-2004-04-1430. Epub 2004 Aug 24.
We found that supernatants of leukapheresis products (SLPs) of patients mobilized with granulocyte-colony-stimulating factor (G-CSF) or the various components of SLPs (fibrinogen, fibronectin, soluble vascular cell adhesion molecule-1 [VCAM-1], intercellular adhesion molecule-1 [ICAM-1], and urokinase plasminogen activator receptor [uPAR]) increase the chemotactic responses of hematopoietic stem/progenitor cells (HSPCs) to stromal-derived factor-1 (SDF-1). However, alone they do not chemoattract HSPCs, but they do increase or prime the cells' chemotactic responses to a low or threshold dose of SDF-1. We observed that SLPs increased calcium flux, phosphorylation of mitogen-activated protein kinase (MAPK) p42/44 and AKT, secretion of matrix metalloproteinases, and adhesion to endothelium in CD34+ cells. Furthermore, SLPs increased SDF-dependent actin polymerization and significantly enhanced the homing of human cord blood (CB)- and bone marrow (BM)-derived CD34+ cells in a NOD/SCID mouse transplantation model. Moreover, the sensitization or priming of cell chemotaxis to an SDF-1 gradient was dependent on cholesterol content in the cell membrane and on the incorporation of the SDF-1 binding receptor CXCR4 and the small GTPase Rac-1 into membrane lipid rafts. This colocalization of CXCR4 and Rac-1 in lipid rafts facilitated guanosine triphosphate (GTP) binding/activation of Rac-1. Hence, we postulate that CXCR4 could be primed by various factors related to leukapheresis and mobilization that increase its association with membrane lipid rafts, allowing the HSPCs to better sense the SDF-1 gradient. This may partially explain why HSPCs from mobilized peripheral blood leukapheresis products engraft more quickly in patients than do those from BM or CB. Based on our findings, we suggest that the homing of HSPCs is optimal when CXCR4 is incorporated in membrane lipid rafts and that ex vivo priming of HSPCs with some of the SLP-related molecules before transplantation could increase their engraftment.
我们发现，用粒细胞集落刺激因子（G-CSF）动员的患者白细胞分离产物上清液（SLPs）或SLPs的各种成分（纤维蛋白原、纤连蛋白、可溶性血管细胞黏附分子-1 [VCAM-1]、细胞间黏附分子-1 [ICAM-1]和尿激酶型纤溶酶原激活物受体[uPAR]）可增强造血干/祖细胞（HSPCs）对基质细胞衍生因子-1（SDF-1）的趋化反应。然而，它们单独不能趋化HSPCs，但能增强或使细胞对低剂量或阈值剂量SDF-1的趋化反应致敏。我们观察到SLPs可增加钙通量、丝裂原活化蛋白激酶（MAPK）p42/44和AKT的磷酸化、基质金属蛋白酶的分泌以及CD34+细胞与内皮的黏附。此外，在NOD/SCID小鼠移植模型中，SLPs可增加SDF依赖的肌动蛋白聚合，并显著增强人脐血（CB）和骨髓（BM）来源的CD34+细胞的归巢。而且，细胞对SDF-1梯度趋化性的致敏或启动取决于细胞膜中的胆固醇含量以及SDF-1结合受体CXCR4和小GTP酶Rac-1掺入膜脂筏。CXCR4和Rac-1在脂筏中的这种共定位促进了鸟苷三磷酸（GTP）与Rac-1的结合/激活。因此，我们推测CXCR4可被与白细胞分离和动员相关的各种因素启动，这些因素增加了其与膜脂筏的结合，使HSPCs能够更好地感知SDF-1梯度。这可能部分解释了为什么动员外周血白细胞分离产物中的HSPCs比骨髓或脐血来源的HSPCs在患者体内更快植入。基于我们的发现，我们认为当CXCR4掺入膜脂筏时HSPCs的归巢最佳，并且在移植前用一些与SLP相关的分子对HSPCs进行体外启动可增加其植入。
