Stem Cell Mobilization As Therapy For Myocardial Ischemi

循环内皮祖细胞（EPCs）可能具有修复心血管损伤的功能，但在冠状动脉疾病患者中功能降低。粒细胞集落刺激因子（G-CSF）可动员CD34+造血祖细胞，其中可能包括由CD133和VEGFR-2标记物鉴定的EPC谱系细胞。研究表明，12例慢性心肌缺血患者每天给予G-CSF 10 ig/kg，连续5天，使循环CD34+/CD133+细胞增加到约60个/il血，比基础水平增加200倍。G-CSF也动员了具有与EPC表型一致的CD133/VEGFR-2表面标记的细胞，尽管血液中的绝对数量很少（约6个细胞/il）。CD133+细胞共表达趋化因子受体CXCR4，这可能是EPCs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。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值。然而，在这个时间点，单核细胞显示成熟内皮细胞上发现的标记物[CD144 (VE-cadherin), CD31 (PECAM), CD51/61 （avaIII整合素）]的表达增加。为了确定EPCs在冠状动脉疾病中的功能特性，将6例患者的单个核细胞用EPCs生长培养基涂于纤维连接蛋白上一周，并检测成熟内皮细胞外生长的菌落（通过摄取荧光双乙酰化LDL证实）。预处理后的EPC集落形成单位低于健康对照组。然而，在给予G-CSF后，患者的EPC集落形成单位增加了近30倍。这些发现表明，冠状动脉疾病患者给予G-CSF可增加循环CD34+/CD133+细胞的数量，其中包括EPC亚群。此外，在接受G-CSF的患者中，集落形成能力（EPC活力的功能指标）受到刺激。趋化因子受体的表达也增加，除了在治疗后一周表达成熟内皮标志物的细胞持续增加。在慢性缺血性心脏病患者中，被动员进入循环并被G-CSF激活的EPCs是否在数量和归家效率上足以启动血管生成和心肌细胞修复，必须在临床试验中进行检验。

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.