Endothelial cell factors mediate the repair of the irradiation hematopoietic comp

最近的估计表明，除非进行医疗干预，否则50%受到400 cGy照射的个人将在60天内死亡，据此可以判断恐怖主义驱动的核或放射性灾难的潜在严重性。虽然离辐射爆炸中心最近的人中有一定比例会因焚烧或创伤而死亡，但相当大比例的受害者将主要受到电离辐射照射。这些人的大多数死亡可能是由于辐射对骨髓和免疫系统的有害影响。不幸的是，暴露于400 cGy - 1000 cGy范围内的辐射剂量的个体将经常死于骨髓衰竭的后遗症（感染、出血并发症），尽管进行了最大限度的支持性护理。我们的实验室已经开发了通过与原代内皮细胞共培养来培养和扩增正常小鼠、灵长类动物和人类造血干细胞的方法。原代EC支持人干细胞在不存在细胞因子的情况下1- 2log扩增。 细胞与细胞接触，表明EC衍生的可溶性因子解释了这种效应。来自原代EC的条件培养基还支持从致死性辐照动物收获后BM干细胞的功能恢复。在该提案中，我们的目的是表征单独施用无血清EC-CM以拯救体内造血活性并改善暴露于高剂量电离辐射后的动物存活率的能力。其次，我们将应用消减基因表达分析和RNA干扰方法来确定EC基因负责独特的可溶性造血和辐射防护作用的EC产生。第三，我们将应用蛋白质分级分离方法纯化和鉴定候选可溶性因子，作为与我们的基因表达和siRNA方法的互补和协同策略。我们预计，该项目的完成将导致一种可交付的治疗方法，不仅用于放射病，而且更广泛地用于加速医学指示疗法（例如化疗，放疗，移植）后的造血恢复。

The potential severity of a terrorist-driven nuclear or radiological catastrophe may be judged by the recent estimate that 50% of individuals exposed to 400 cGy will die within 60 days unless there is medical intervention. While a percentage of individuals closest to the epicenter of a radiation blast would be killed by incineration or trauma, a significant percentage of victims will be exposed to primarily ionizing radiation exposure. The majority of deaths in these individuals will likely occur due to the deleterious effects of radiation on the bone marrow and immune system. Unfortunately, individuals exposed to radiation doses ranging from 400 cGy - 1000 cGy will frequently die from the sequelae of bone marrow failure (infections, bleeding complications) despite maximal supportive care. Our laboratory has developed methods to cultivate and expand normal murine, primate, and human hematopoietic stem cells via co-culture with primary endothelial cells. Primary ECs support a 1-2 log expansion of human stem cells in the absence of cell-to-cell contact, indicating that EC-derived soluble factors account for this effect. Conditioned medium from primary ECs also supports the functional recovery of BM stem cells following harvest from lethally irradiated animals. In this proposal we aim to characterize the capacity for administered serum free EC-CM alone to rescue in vivo hematopoietic activity and improve survival in animals after exposure to high dose ionizing radiation. Second, we will apply subtractive gene expression analysis and RNA interference methods to identify the EC genes responsible for the uniquely soluble hematopoietic and radioprotective effect produced by ECs. Third, we will apply protein fractionation methods to purify and identify the candidate soluble factors as a complementary and synergistic strategy with our gene expression and siRNA approach. We anticipate that the completion of this project will lead to a deliverable therapeutic not only for radiation sickness, but more broadly, to accelerate hematopoietic recovery following medically indicated therapies (e.g. chemotherapy, radiotherapy, transplantation).