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

造血干细胞移植(HSCT)治愈了一系列致命的疾病，包括 免疫缺陷、骨髓衰竭和恶性肿瘤，以及20,000多例HSCT 在美国每年都会发生。几十年的研究减少了移植后的发病率和 提高了存活率，但障碍仍然很大，包括需要最佳地植入 捐赠者干细胞。事实上，关于必要的遗传和分子成分的知识 对于HSC来说，动态平衡和移植后植入仍然不完整。我们已经确定了 卵泡抑素样蛋白1(FSTL-1)对于造血干细胞移植后的多系重建至关重要，但 机制仍不清楚。在转录水平上，FSTL-1在罕见的 自我更新长期HSC的种群(LT-HSC)。我们的初步数据和报告来自 这些文献使我们假设FSTL1对HSC的动态平衡和 移植后细胞植入通过其促进LT-HSC的静止。这 IDEA将在两个具体目标上进行测试。 目的1确定FSTL-1缺乏对HSC动态平衡的影响。使用 FSTL-1条件基因敲除(CKO)模型，我们将确定哪些HSC群体和 动态平衡条件下FSTL-1缺乏对细胞通路的影响 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的调节对HSC和骨髓的影响 嫁接。在这里，使用FSTL-1 CKO细胞，我们将确定FSTL-1的影响 直接在高纯度的LT-HSCs群体中缺乏，并将决定FSTL-1在 采用连续移植和体外集落形成实验进行造血干细胞自我更新。另外，我们 将开发一种用于异位表达FSTL-1的慢病毒系统，随后将努力拯救 FSTL-1缺陷细胞植入减少。最后，我们将测试慢病毒驱动的 FSTL-1的表达不依赖于FSTL-1的缺乏，可以促进HSCT的植入。 总而言之，拟议的研究将集中于确定FSTL-1在HSC中的作用 动态平衡和免疫重建。这一发现将有益于干细胞生物学领域， 免疫系统的发展，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，这部作品将为小说 在原发免疫缺陷和受损领域改善人类疾病的途径 造血干细胞功能，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.