Stem Cell Mobilization As Therapy For Myocardial Ischemi

循环内皮祖细胞(EPC)可能具有修复心血管损伤的功能，但在冠心病患者中会减少。粒细胞集落刺激因子(G-CSF)动员CD34+造血祖细胞，可能包括CD133和VEGFR-2标志物鉴定的EPC系细胞。我们发现，对于12名慢性心肌缺血患者，每天给予G-CSF10g/kg，连续5天，可使循环CD34+/CD133+细胞增加到约60个/il血液细胞，比基础水平增加200倍。G-CSF也动员了CD133/VEGFR-2表面标志与EPC表型一致的细胞，尽管血液中的绝对数量很少(约6个/il)。CD133+细胞共表达趋化因子受体CXCR4，这可能是内皮祖细胞向表达其同源配体基质衍生因子的缺血组织归巢的重要因素。在G-CSF治疗完成一周后，CD133/CXCR4表面标记的细胞水平恢复到基线水平。然而，在这个时间点，单个核细胞显示成熟内皮细胞上的标志物[CD144(VE-钙粘素)，CD31(PECAM)，CD51/61(avaIII整合素)]的表达增加。为了确定冠状动脉疾病患者外周血中内皮祖细胞的功能特性，将6例患者的单个核细胞接种于含内皮细胞生长介质的纤维连接蛋白上1周，检测成熟内皮细胞过度生长的集落(通过摄取荧光DiI-乙酰化低密度脂蛋白证实)。治疗前EPC集落形成单位低于健康对照组。然而，在注射G-CSF后，患者的EPC集落形成单位几乎增加了30倍。这些发现证实，冠状动脉疾病患者应用G-CSF可增加循环中CD34+/CD133+细胞的数量，其中包括EPC亚群。此外，集落形成能力，一种衡量内皮祖细胞活性的功能指标，在接受G-CSF的患者中得到刺激。趋化因子受体的表达也增加，此外，在治疗后一周，细胞表达成熟的内皮标记物持续增加。动员到循环中并被G-CSF激活的内皮祖细胞是否在数量和归巢效率上足以启动慢性缺血性心脏病患者的血管生成和心肌细胞修复，必须在临床试验中进行测试。

Circulating endothelial progenitor cells (EPCs) may function to repair cardiovascular injury, but are reduced in patients with coronary artery disease. Granulocyte-colony stimulating factor (G-CSF) mobilizes CD34+ hematopoietic progenitor cells, which may include cells of EPC lineage identified by the markers CD133 and VEGFR-2. We show that G-CSF 10 ig/kg administered daily for 5 days to 12 patients with chronic myocardial ischemia increased circulating CD34+/CD133+ cells to approximately 60 cells/il blood, a 200-fold increase from basal levels. Also mobilized by G-CSF were cells with CD133/VEGFR-2 surface markers consistent with EPC phenotype, although the absolute number in blood was small (approximately 6 cells/il). CD133+ cells coexpressed the chemokine receptor CXCR4, which may be important for homing of EPCs to ischemic tissue expressing its cognate ligand, stromal-derived factor. One week following completion of G-CSF treatment, levels of cells with CD133/CXCR4 surface markers returned towards baseline values. At this time-point, however, mononuclear cells showed increased expression of markers found on mature endothelial cells [CD144 (VE-cadherin), CD31 (PECAM), CD51/61 (avaIII integrin)]. In order to determine functional properties of EPCs in coronary artery disease, mononuclear cells from 6 patients were plated on fibronectin with EPC growth media for one week, and assayed for colonies with out-growth of mature endothelial cells (confirmed by uptake of fluorescent DiI-acetylated LDL). Pre-treatment EPC colony-forming units were lower than in healthy controls. Following G-CSF administration, however, patients showed an almost 30-fold increase in EPC colony-forming units. These findings establish that G-CSF administration to patients with coronary artery disease increases numbers of circulating CD34+/CD133+ cells, which includes the EPC sub-set. Additionally, colony-forming capacity, a functional measure of EPC viability, is stimulated in patients receiving G-CSF. Chemokine receptor expression is also increased, in addition to sustained increase in cells expressing mature endothelial markers at one week following treatment. Whether EPCs mobilized into the circulation and activated by G-CSF will be sufficient in number and homing efficiency to initiate vasculogenesis and myocyte repair in patients with chronic ischemic heart disease must be tested in clinical trials.