内皮祖细胞在炎症损伤修复中的作用和机制

Effect and mechanism of endothelial progenitor cells in repair of inflammatory injury

内皮祖细胞(endothelial progenitor cells,EPCs)是出生后,可以在机体内分化为成熟内皮细胞的一种前体细胞,主要来源于骨髓。多种伴有血管内皮细胞损伤的疾病都可引起外周血EPCs数量变化。有研究显示EPCs参与炎性损伤修复,并且外周血EPCs数量与血管内皮损伤程度和疾病预后存在一定的相关关系。EPCs通过动员、迁移、归巢和分化等步骤修复内皮。炎症反应中受损组织释放的基质细胞衍生因子、血管内皮生长因子可与EPCs相应的受体结合,通过内皮型一氧化氮合酶、基质金属蛋白酶9等途径调节内皮修复过程,这是EPCs分化为内皮细胞过程的主要调控机制。此外,EPCs还可通过旁分泌机制促进相邻的内皮细胞增殖分化。目前,EPCs在炎症领域仅用于内皮炎性损伤和疾病预后评估,但是EPCs在心血管疾病和组织工程领域应用研究的成功,为EPCs在炎症反应的诊断和治疗提供了新的思路。

Endothelial progenitor cells （EPCs）, derived mainly from bone marrow, are the precursor cells that can differentiate to mature endothelial cells （ECs） postnatally. The level of circulating EPCs may change when impairment of vascular ECs occurs under many pathologic conditions. Extensive studies have demonstrated that EPCs participate in the repair of inflammatory injury. In addition, the changes of circulating EPCs level have been shown to be associated with the degree of inflammatory injury of blood vessel endothelium and prognosis of diseases. EPCs participate in the endothelium repair by performing mobilization, migration, homing and differentiation. The major mechanisms underlying the differentiation of EPCs to ECs are that stroma cell-derived factor and vascular endothelial growth factor secreted from injured tissues in inflammation can bind to the receptors on EPCs to modulate reparative process through activation of eNOS and matrix metalloproteinase 9 and other pathways. Furthermore, EPCs can promote the proliferation and differentiation of adjacent ECs through paracrine secretion. Currently, the level of circulation EPCs is considered an index to evaluate injury of blood vessel endothelium and prognostic of diseases. The successful use of EPCs in cardiovascular disease and tissue engineering in many studies indicates the effect of EPCs in the repair of endothelium and tissue injury and may suggest a＇novel approach in the diagnosis and treatment of inflammation.