Hung Shih-Chieh, Pochampally Radhika R, Chen Sy-Chi, Hsu Shu-Ching, Prockop Darwin J
Center for Gene Therapy, Tulane University Health Sciences Center, 1430 Tulane Avenue, New Orleans, Louisiana 70112, USA.
Stem Cells. 2007 Sep;25(9):2363-70. doi: 10.1634/stemcells.2006-0686. Epub 2007 May 31.
Recent reports indicated that vascular remodeling and angiogenesis are promoted by conditioned medium from the cells referred to as multipotent stromal cells (MSCs). However, the molecular events triggered by MSC-conditioned medium (CdM) were not defined. We examined the effects of CdM from human MSCs on cultures of primary human aortic endothelial cells (HAECs). The CdM inhibited hypoxia-induced apoptosis and cell death of HAECs. It also promoted tube formation by HAECs in an assay in vitro. Conditioned medium from multipotent stromal cells incubated under hypoxic conditions in serum-free endothelial basal medium for 2 days (CdM(Hyp)) from hypoxic culture of MSCs was more effective than conditioned medium from MSCs incubated under normoxic conditions in serum-free endothelial basal medium for 2 days from normoxic cultures of MSCs, an observation in part explained by its higher content of antiapoptotic and angiogenic factors, such as interleukin (IL)-6, vascular endothelial growth factor (VEGF), and monocyte chemoattractant protein (MCP)-1. The effects of CdM(Hyp) on hypoxic HAECs were partially duplicated by the addition of IL-6 in a dose-dependent manner; however, anti-IL-6, anti-MCP-1, and anti-VEGF blocking antibodies added independently did not attenuate the effects. Also, addition of CdM(Hyp) activated the PI3K-Akt pathway; the levels of p-Akt and several of its downstream targets were increased by CdM(Hyp), and both the increase in p-Akt and the increase in angiogenesis were blocked by an inhibitor of PI3K-Akt or by expression of a dominant negative gene for PI3K. CdM(Hyp) also increased the levels of p-extracellular signal-regulated kinase (ERK), but there was a minimal effect on p-signal transducer and activator of transcription-3, and an inhibitor of the ERK1/2 pathway had no effect on hypoxia-induced apoptosis of the HAECs. The results are consistent with suggestions that administration of MSCs or factors secreted by MSCs may provide a therapeutic method of decreasing apoptosis and enhancing angiogenesis.
最近的报告表明，被称为多能基质细胞（MSCs）的细胞所分泌的条件培养基可促进血管重塑和血管生成。然而，MSCs条件培养基（CdM）引发的分子事件尚未明确。我们研究了人MSCs的CdM对原代人主动脉内皮细胞（HAECs）培养的影响。CdM可抑制缺氧诱导的HAECs凋亡和细胞死亡。在体外试验中，它还能促进HAECs形成管腔。在无血清内皮基础培养基中于缺氧条件下培养2天的多能基质细胞的条件培养基（CdM(Hyp)），相较于在无血清内皮基础培养基中于常氧条件下培养2天的MSCs常氧培养条件培养基，其效果更佳，这一现象部分可归因于其抗凋亡和促血管生成因子含量更高，如白细胞介素（IL）-6、血管内皮生长因子（VEGF）和单核细胞趋化蛋白（MCP）-1。CdM(Hyp)对缺氧HAECs的作用可通过以剂量依赖方式添加IL-6部分重现；然而，单独添加抗IL-6、抗MCP-1和抗VEGF阻断抗体并不能减弱其作用。此外，添加CdM(Hyp)可激活PI3K-Akt信号通路；CdM(Hyp)可使p-Akt及其几个下游靶点的水平升高，PI3K-Akt抑制剂或PI3K显性负基因的表达可同时阻断p-Akt的升高和血管生成的增加。CdM(Hyp)还可提高p-细胞外信号调节激酶（ERK）的水平，但对p-信号转导和转录激活因子3的影响极小，且ERK1/2信号通路抑制剂对缺氧诱导的HAECs凋亡无作用。这些结果与以下观点一致，即给予MSCs或MSCs分泌的因子可能提供一种减少凋亡和增强血管生成的治疗方法。
