FSTL-1 Regulated Pathways in Hematopoietic Stem Cell Homeostasis and Transplantation

造血干细胞移植（HSCT）可以治愈一系列致命疾病，包括 免疫缺陷、骨髓（BM）衰竭和恶性肿瘤，以及超过20，000例HSCT 几十年的研究已经降低了移植后的发病率， 提高生存率，但障碍仍然很大，包括需要最佳的植入， 捐献的干细胞事实上，关于遗传和分子组成的知识是必要的， 造血干细胞稳态和移植后的植入仍然不完全。我们已经确定 卵泡抑素样1（FSTL-1）是HSCT后多谱系重建的关键，但 机制仍然未知。在转录上，FSTL-1在罕见的 自我更新的长期HSC（LT-HSC）。我们的初步数据和报告， 文献使我们假设Fstl 1对于HSC稳态和 通过促进LT-HSC的静止来促进移植后细胞的植入。这 这些想法将在两个具体目标中得到验证。 目的1将确定FSTL-1缺陷对HSC稳态的影响。使用 FSTL-1条件性敲除（CKO）模型，我们将确定哪些HSC群体和 细胞通路在稳态条件下受到FSTL-1缺陷的影响， FSTL-1缺陷细胞对5-氟尿嘧啶诱导的细胞周期毒性的反应。 目的2将确定FSTL-1调节对HSC和骨髓的影响。 移植在这里，使用FSTL-1 CKO细胞，我们将确定FSTL-1的影响 在高度纯化的LT-HSC群体中直接缺乏FSTL-1，并将决定FSTL-1在 使用连续移植和体外集落形成测定的HSC自我更新。另外，我们 将开发一种用于异位FSTL-1表达的慢病毒系统，随后将努力拯救FSTL-1。 减少FSTL-1缺陷细胞的植入。最后，我们将测试慢病毒驱动的 FSTL-1表达可增强HSCT植入，而不依赖于FSTL-1缺陷。 累积起来，拟议的研究将集中于确定FSTL-1在HSC中的作用。 体内平衡和免疫重建。这些发现将有利于干细胞生物学领域， 免疫系统发育和细胞移植的临床前建模，以及 FSTL-1细胞和分子信号转导的研究。最终，这项工作将告知小说 在原发性免疫缺陷和受损领域改善人类疾病的方法 HSC功能，以及血液和骨髓移植。

Hematopoietic stem cell transplantation (HSCT) cures a range of fatal conditions including immunodeficiency, bone marrow (BM) failure, and malignancy, and more than 20,000 HSCTs occur annually in the U.S. Decades of research have reduced post-transplant morbidity and improved survival, but barriers remain substantial including the need for optimal engraftment of donor stem cells. Indeed, knowledge about the genetic and molecular constituents necessary for HSC homeostasis and post-transplant engraftment remain incomplete. We have identified that follistatin-like 1 (FSTL-1) is critical for multilineage reconstitution following HSCT, but the mechanism remains unknown. Transcriptionally, FSTL-1 is most highly expressed in the rare population of self-renewing Long-term HSC (LT-HSC). Our preliminary data and reports from the literature lead us to hypothesize that Fstl1 is critical for both HSC homeostasis and post-transplant cellular engraftment through its promotion of LT-HSC quiescence. This idea will be tested in two Specific Aims. Aim 1 will determine the impact of FSTL-1 deficiency on HSC homeostasis. Using a FSTL-1 conditional knock-out (CKO) model, we will determine which HSC populations and cellular pathways are impacted by FSTL-1 deficiency under homeostatic conditions as well as the response of FSTL-1 deficient cells to 5-flurouracil induced cell-cycling toxicity. Aim 2 will determine the impact of FSTL-1 modulation on HSC and bone marrow engraftment. Here, using FSTL-1 CKO cells, we will determine the impact of FSTL-1 deficiency directly in a highly purified LT-HSCs population and will determine FSTL-1 role in HSC self-renewal using serial transplantation and in vitro colony-forming assays. Separately, we will develop a lentiviral system for ectopic FSTL-1 expression, followed by efforts to rescue the diminished engraftment of FSTL-1-deficient cells. Finally, we will test whether lentiviral-driven FSTL-1 expression can enhance HSCT engraftment independent of FSTL-1 deficiency. Cumulatively, the proposed studies will focus on defining the role of FSTL-1 in HSC homeostasis and immune reconstitution. The findings will benefit the fields of stem cell biology, immune system development, and preclinical modeling of cellular transplantation, as well as the study of FSTL-1 cellular and molecular signaling. Ultimately, this work will inform novel approaches to improve human disease in the fields of primary immunodeficiency and impaired HSC function, and blood and marrow transplantation.