Role of PGE2 and other eicosanoids in hematopoietic stem cell function

描述（由申请人提供）：造血干细胞移植是血液学和非血液学和遗传性疾病的潜在治愈性疗法;然而，干细胞数量和功能的限制可能影响植入率和结局。在这项提案中，我们将研究类花生酸在促进干细胞收集和增强其移植后的植入和自我更新方面的作用机制。我们相信我们获得的信息可以直接转化为改善造血干细胞移植。类花生酸是生理脂质，包括肾上腺素，前列环素，血栓烷，白三烯和内源性大麻素。我们的早期研究表明，前列腺素E2（PGE 2）在正常和异常造血中具有重要的负性和正性生理作用。最近的证据表明，体外短期给予PGE 2可以增强造血干细胞和祖细胞（HSPC）的植入。在 在本申请中，我们提出了新的初步发现，表明PGE 2可以增加HSPC的存活、归巢和细胞周期速率。在具体目标1中，我们将研究PGE 2在增强HSPC植入中的作用机制，并确定负责PGE 2介导的HSPC存活、归巢和细胞周期增强的受体亚型和信号传导途径，并评估其他类花生酸对HSC功能的作用。骨髓是一个动态的组织，PGE 2的造血作用是复杂的，可以是阳性和阴性的，直接或放大或通过辅助细胞介导。我们已经广泛地表征了PGE 2在体内细胞增殖和分化中的生理作用，至少在祖细胞水平上。然而，鉴于我们今天有能力精确监测HSC的命运和功能，关键是要确定内源性和外源性PGE 2在宿主骨髓中的作用，以确定PGE 2合成的正或负调节是否会进一步促进或潜在地损害HSC植入。在具体目标2中，我们将通过使用选择性激动剂/拮抗剂给药和/或选择性阻断体内PGE 2或替代类二十烷酸产生来评估内源性PGE 2和其他类二十烷酸对干细胞功能和造血微环境的作用。G-CSF动员的外周血干细胞是目前用于移植的主要造血移植物。初步研究结果表明，PG生物合成的阻断增强了G-CSF的动员，并且内源性大麻素，具有与Eglandins相反的活性的类花生酸家族的成员也可以动员HPC并与G-CSF协同作用。在具体目标3中，我们将评估类花生酸途径调节对于改善造血动员和移植的效用，并表征类花生酸途径动员的细胞的干细胞性质。 公共卫生相关性：造血干细胞（HSC）移植是一种治愈性治疗;但HSC数量的限制影响植入和结局。动员的外周血造血干细胞被广泛使用，但在患者和正常供体中发生动员不良，导致无法收集足够的造血干细胞。脐带血是一种相对未开发的HSC来源;然而，可以获得的干细胞总数通常太少，无法进行成人移植。在本提案中，我们将研究类花生酸增强HSC功能和促进所有来源HSC植入的机制，以及调节类花生酸产生和活性以获得更多HSC用于移植的方法。如果成功，我们获得的信息将大大增强获得更多可移植HSC的能力，并更有效地将其输送到骨髓龛，并可以快速直接地转化为改善造血干细胞移植。

DESCRIPTION (provided by applicant): Hematopoietic stem cell transplant is a potentially curative therapy for hematologic and non-hematologic and genetic disorders; however limitations in stem cell number and function can affect engraftment rate and outcomes. In this proposal we will investigate the mechanism of action of eicosanoids in facilitating collection of stem cells and enhancing their engraftment and self-renewal upon transplantation. We believe that the information we derive can be directly translated to improve hematopoietic stem cell transplantation.Eicosanoids are physiological lipids that include prostaglandins, prostacyclins, thromboxanes, leukotrienes, and endocannabinoids. Our early studies demonstrated important negative and positive physiological roles forprostaglandin E2 (PGE2) in normal and abnormal hematopoiesis. Recent evidence suggests that short-term in vitro xposure to PGE2 can enhance the engraftment of hematopoietic stem and progenitor cells (HSPC). In this application, we present new preliminary findings that indicate that PGE2 can increase survival, homing and cell cycle rate of HSPC. In specific aim 1, we will investigate the mechanism of action of PGE2 in enhancing HSPC engraftment and define the receptor subtype and signaling pathways responsible for PGE2-mediated enhancement of HSPC survival, homing and cell cycle and evaluate the role of other eicosanoids on HSC function. Bone marrow is a dynamic tissue and hematopoietic effects of PGE2 are complex and can be positive and negative and direct or amplified or mediated through accessory cells. We have extensively characterized the physiological roles PGE2 can play in cell proliferation and differentiation in vivo, at least at the progenitor cell level. However, given the ability we have today to precisely monitor HSC fate and function, it is critical to define the roles of endogenous and exogenous PGE2 within the host bone marrow in order to determine whether positive or negative modulation of PGE2 synthesis could further facilitate or potentially damage HSC engraftment. In specific aim 2, we will evaluate the roles of endogenous PGE2 and other icosanoids on stem cell function and the hematopoietic microenvironment through the use of selective agonist/antagonist administration and/or selective blockade of PGE2 or alternate eicosanoid production in vivo. G-CSF mobilized peripheral blood stem cells are the primary hematopoietic graft in use for transplant today. Preliminary findings indicate that blockade of PG biosynthesis enhances mobilization by G-CSF and that endocannabinoids, members of the eicosanoid family with activities generally opposite that of the prostaglandins can also mobilize HPC and synergize with G-CSF. In specific aim 3 we will evaluate the utility of eicosanoid pathway modulation for improved hematopoietic mobilization and transplantation and characterize the stem cell roperties of eicosanoid pathway mobilized cells. PUBLIC HEALTH RELEVANCE:Hematopoietic stem cell (HSC) transplantation is a curative therapy; but limitations in HSC number affects engraftment and outcome. Mobilized peripheral blood HSC are widely used, however poor mobilization in patients and normal donors occurs, resulting in inability to collect sufficient HSC. Umbilical cord blood is a relatively untapped source of HSC; however the total number of stem cells that can be obtained is usually too small for adult transplants. In this proposal we will investigate the mechanisms by which eicosanoids enhance HSC function and facilitate engraftment of HSC from all sources , as well as methods to modulate eicosanoid production and activity to obtain more HSC for transplant. If successful, the information we derive will greatly augment the ability to obtain more engraftable HSC and more efficiently deliver them to their marrow niches and can be rapidly and directly translated to improve hematopoietic stem cell transplantation.