Role of PGE2 and other eicosanoids in hematopoietic stem cell function

描述(申请人提供)：造血干细胞移植是一种治疗血液病、非血液病和遗传性疾病的潜在疗法；然而，干细胞数量和功能的限制可能会影响植入率和结果。在这项建议中，我们将研究二十烷类化合物在促进干细胞收集、增强干细胞植入和移植后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的方法。二十烷基类化合物是包括前列腺素、前列环素、血栓烷、白三烯和内源性大麻素在内的生理类脂。我们早期的研究表明，前列腺素E_2(PGE_2)在正常和异常的造血中具有重要的正、负性生理作用。最近的证据表明，PGE2的短期体外暴露可以促进造血干/祖细胞(HSPC)的植入。在……里面 在这一应用中，我们提出了新的初步发现，表明PGE2可以提高HSPC的存活率、归巢能力和细胞周期。在特定的目标1中，我们将研究PGE2促进HSPC植入的作用机制，确定PGE2介导的促进HSPC存活、归巢和细胞周期的受体亚型和信号通路，并评价其他二十烷类化合物对HSC功能的作用。骨髓是一个动态的组织，PGE2的造血作用是复杂的，可以是阳性的，也可以是阴性的，可以是直接的，也可以是通过辅助细胞扩增或介导的。我们已经广泛地表征了PGE2在体内细胞增殖和分化中所起的生理作用，至少在祖细胞水平上是这样。然而，鉴于我们今天有能力精确地监测HSC的命运和功能，关键是要确定内源性和外源性PGE2在宿主骨髓中的作用，以确定PGE2合成的正向或负向调节是否会进一步促进或潜在地损害HSC的植入。在具体目标2中，我们将通过使用选择性激动剂/拮抗剂和/或选择性阻断PGE2或体内交替产生二十烷类化合物来评估内源性PGE2和其他二十烷类化合物对干细胞功能和造血微环境的作用。粒细胞集落刺激因子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，阻断PG的生物合成可增强G-CSF的动员作用，而二十烷类化合物中的内源性大麻素类化合物也能动员HPC并与G-CSF协同作用。在具体目标3中，我们将评估二十烷类途径调节在改善造血动员和移植方面的作用，并表征二十烷类途径动员细胞的干细胞特性。

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.