Rejuvenation of aged hematopoietic stem cells and endothelial niches by thrombospondin-1 blockade

通过血小板反应蛋白-1 阻断使衰老的造血干细胞和内皮微环境恢复活力

• 批准号: 10709177
• 负责人: Jason Mathew Butler
• 金额: $ 21.75万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-23 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10709177
• 关键词: Rejuvenation; aged; hematopoietic; stem; cells

PROJECT SUMMARY There is a substantial need for the development of preventative and therapeutic options to delay the aging process, to rejuvenate tissue/organs, and to enhance regeneration and repair. Aging of the blood system is associated with loss of vascular integrity and dramatic changes in hematopoietic stem cell (HSC) function. In addition to increasing in number and losing self-renewal potential, old HSCs exhibit a myeloid bias and increased propensity to develop hematologic malignancies. While some of these changes reflect cell-intrinsic alterations, emerging evidence suggests that some of these defects may also be regulated by the bone marrow (BM) microenvironment, in particular the BM endothelial niche. In particular, we have demonstrated that the BM endothelial niche is indispensable for supporting the balance between HSC self-renewal and differentiation following myeloablative insult. We have also shown that AKT/mTOR signaling in BM endothelial cells (BMECs) is required for maintenance of the HSCs and that this signaling is disrupted in aged BMECs. To ask how a disruption of the AKT/mTOR signaling axis in ECs affects the hematopoietic system, we have conditionally deleted mTOR in adult ECs (mTOR(ECKO) mice) and found that this deletion resulted in the premature aging of HSCs as demonstrated by their phenotypic, functional, and transcriptional analysis. To better understand how EC-mediated signaling drives the aging of the hematopoietic system, we utilized our mTOR(ECKO) mouse model as a screening tool to discover as yet unknown pro-HSC-aging factors. Transcriptomic and proteomic studies identified Thrombospondin-1 (TSP1) as a candidate pro-aging factor that was commonly upregulated in mTOR(ECKO) and aged mice when compared to young controls. Moreover, global knockout of TSP1 resulted in preservation and rejuvenation of HSC function in aged mice. This research proposal is designed to test whether it is possible to: 1) reverse the age-related phenotypes of the hematopoietic and vascular systems by global or cell-specific deletion, or antibody-mediated inhibition, of TSP1, 2) enhance the ex vivo expansion and function of aged HSC by exogenous inhibition of TSP1, and 3) rejuvenate an aged BM microenvironment following myelosuppressive treatments by utilizing young BMECs as a cellular therapeutic with or without the co-infusion of a neutralizing antibody to TSP1. The proposed studies will utilize novel in vivo and in vitro models developed in our lab and, if successful, will unlock the therapeutic potential of TSP1 inhibition to improve overall healthspan, longevity, and regeneration of the hematopoietic system in the elderly. The success of this research proposal will open up new avenues for the development of a wide array of therapeutic strategies designed as an effective means to reverse age-related hematopoietic deficiencies.

项目概要 迫切需要开发预防和治疗方案来延缓衰老 过程，使组织/器官恢复活力，并增强再生和修复。血液系统的老化是 与血管完整性丧失和造血干细胞（HSC）功能的巨大变化有关。在 除了数量增加和失去自我更新潜力外，旧的 HSC 还表现出骨髓偏向性，并且增加 发生血液系统恶性肿瘤的倾向。虽然其中一些变化反映了细胞内在的改变， 新出现的证据表明，其中一些缺陷也可能受到骨髓 (BM) 的调节 微环境，特别是骨髓内皮细胞微环境。特别是，我们已经证明了 BM 内皮生态位对于支持 HSC 自我更新和分化之间的平衡是不可或缺的 清髓性损伤后。我们还发现 BM 内皮细胞 (BMEC) 中的 AKT/mTOR 信号传导 是维持 HSC 所必需的，但这种信号在老化的 BMEC 中会被破坏。要问如何一个 EC 中 AKT/mTOR 信号轴的破坏会影响造血系统，我们有条件地 在成年EC（mTOR（ECKO）小鼠）中删除mTOR，发现这种删除导致了早衰 通过表型、功能和转录分析证明 HSC。为了更好地理解如何 EC 介导的信号传导驱动造血系统老化，我们利用我们的 mTOR(ECKO) 小鼠模型 作为发现尚未知的促 HSC 衰老因子的筛查工具。转录组学和蛋白质组学研究 确定 Thrombospondin-1 (TSP1) 是一种候选促衰老因子，在 mTOR(ECKO) 和老年小鼠与年轻对照组相比。此外，TSP1 的全局敲除导致 老年小鼠 HSC 功能的保存和恢复。本研究计划旨在测试是否 有可能：1）通过整体或逆转造血和血管系统与年龄相关的表型 TSP1 的细胞特异性缺失或抗体介导的抑制，2) 增强离体扩增和功能 通过外源性抑制 TSP1 来抑制老化的 HSC，以及 3) 使老化的 BM 微环境恢复活力 利用年轻的 BMEC 作为细胞治疗剂（有或没有共输注）进行骨髓抑制治疗 TSP1 的中和抗体。拟议的研究将利用开发的新型体内和体外模型 在我们的实验室中，如果成功，将释放 TSP1 抑制的治疗潜力，以改善整体健康寿命， 长寿和老年人造血系统的再生。本研究计划的成功 将为开发一系列广泛的治疗策略开辟新的途径，这些策略被设计为有效的 意味着逆转与年龄相关的造血缺陷。