Medhanism of EPC Dysfunction in the SS Rat: Quantity over Quality

项目摘要 内皮祖细胞（endothelial progenitor cells，EPCs）是成体干细胞，在血管生成和内皮生长中起作用。 功能人类和动物研究表明，使用富含EPC的自体干细胞疗法， 细胞群可用于治疗疾病，如高血压、心肌梗塞、中风， 糖尿病然而，来自患病和衰老宿主的EPCs显示出数量和功能的下降， 可能损害治疗功效，从而掩盖基于EPC的治疗的潜力。的目标 本研究旨在探讨内皮祖细胞血管生成能力受损的机制， EPC功能障碍。在所提出的动物模型中，SS/MCWi（SS）大鼠、EPC能力和寿命是 在体内受损但在体外挽救。我们已经观察到自然杀伤（NK）细胞受体2B4的增加， （CD244）和SS NK细胞对SS EPCs的杀伤增加。我们 假设EPC膜上CD244表达增加导致NK细胞增加， 介导的SS EPCs体内破坏，这损害了它们诱导血管生成的能力。我们 将使用体外细胞毒性试验和后肢血管生成的体内模型来测试 CD244基因敲除和NK细胞耗竭对NK细胞介导的SS破坏和血管生成能力的影响 EPC。我们还将评估各种观察到的CD244转录物序列在一个细胞中的生理影响。 体外细胞培养系统。因为我们之前已经证明，低剂量的血管紧张素II（AngII）可以恢复 SS大鼠的血管生成和SS骨髓单个核细胞的血管生成能力，我们将评估 AngII对SS血管生成能力、CD244表达和NK细胞介导的细胞毒作用的影响 EPC。

Project Summary Endothelial progenitor cells (EPCs) are adult stem cells with roles in angiogenesis and endothelial function. Human and animal studies suggest that autologous stem cell therapy using an EPC enriched population of cells can be therapeutic in diseases such as hypertension, myocardial infarction, stroke, and diabetes. However, EPCs from diseased and aging hosts show decreases in number and function that are likely to compromise therapeutic efficacy, thus masking the potential of EPC based therapy. The objective of this study is to determine the mechanism of impaired angiogenic competency of EPCs in an animal model of EPC dysfunction. In the proposed animal model, the SS/MCWi (SS) rat, EPC competency and longevity is impaired in vivo but rescued in vitro. We have observed an increase in the natural killer (NK) cell receptor 2B4 (CD244) on the membrane of SS EPCs and an increase in killing of SS EPCs by SS NK cells. We hypothesize that increased expression of CD244 on the EPC membrane leads to increased NK cell mediated destruction of SS EPCs in vivo, which compromises their ability to induce angiogenesis. We will use an in vitro cytotoxicity assay and an in vivo model of hind-limb angiogenesis to test the effects of CD244 knockdown and NK cell depletion on NK cell mediated destruction and angiogenic competency of SS EPCs. We will also assess the physiological impact of the various observed CD244 transcript sequences in an in vitro cell culture system. Because we have previously shown that low-dose angiotensin II (AngII) restores angiogenesis in SS rats and angiogenic competency in SS bone marrow mononuclear cells, we will assess the effects of AngII on the angiogenic competency, CD244 expression, and NK cell mediated cytotoxicity of SS EPCs.