The role of macrophage subpopulations in the rejuvenation of fracture repair

巨噬细胞亚群在骨折修复年轻化中的作用

• 批准号: 10544770
• 负责人: Benjamin Aaron Alman
• 金额: $ 42.93万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10544770
• 关键词: Address; Age; Aging; Alleles; Animals; Automobile Driving; Bone Marrow Cells; Bone Marrow Transplantation; Cell Death; Cell Differentiation process; Cell Lineage; Cell Proliferation; Cell secretion; Cells; Characteristics; Circulation; Clinical; Cyclic AMP Receptors; Data; Development; Elderly; Erythro; Exposure to; Genes; In Vitro; Individual; Knowledge; LDL-Receptor Related Protein 1; Label; Macrophage; Mediating; Mesenchymal; Mesenchymal Differentiation; Morbidity - disease rate; Mus; Myelogenous; Myeloid Progenitor Cells; Operative Surgical Procedures; Osteoblasts; Parabiosis; Phenotype; Population; Protein Secretion; Proteins; Recombinants; Rejuvenation; Role; Source; Spleen; Splenectomy; Testing; Undifferentiated; Vascular blood supply; Work; Yolk Sac; aged; beta catenin; bone; bone fracture repair; bone healing; bone repair; cathelicidin antimicrobial peptide; defined contribution; experimental study; fetal; gene function; healing; improved; in vivo; juvenile animal; mature animal; mechanical properties; mortality; novel therapeutic intervention; novel therapeutics; older patient; osteoblast differentiation; progenitor; recruit; repaired; resistin; response; single-cell RNA sequencing

The pace of bone repair slows with aging, increasing the chance of developing a delayed union or non-union. These complications are treated with surgical procedures causing significant morbidity and even mortality, especially in older adults. Here we will build on our previous work using heterochronic parabiosis (in which two mice of a different age share a blood supply) showing that exposure to a young circulation and young macrophage cells rejuvenates fracture repair in older mice. In our preliminary data we used cell lineage tracing analysis and parabiosis experiments to determine the developmental source of macrophage in fracture repair, and found these derived from a subpopulation of cells of yolk sac origin. Interestingly these cells reside in the spleen and are recruited through the circulation during bone repair. As mice age, this subpopulation of cells becomes depleted. In this proposal we study the role of this cell population and the factors they produce in the rejuvenation of fracture repair by undertaking the following aims: 1) Identify the role of macrophages derived from yolk sac progenitors in the rejuvenation of fracture repair. Heterochronic parabiosis in which these cells can be labeled or depleted will be investigated to define the contribution of young cells from this population of macrophage cells that can improve the quality of fracture repair in older animals. 2) Determine the function of genes expressed in unique macrophage subpopulations present in young mice in bone repair: We used single cell RNA sequencing and found a unique subpopulation of macrophages cells present in bone repair in only young animals. Mice lacking genes which encode for secreted proteins in various macrophage populations will be used in heterochronic parabiosis to determine their contribution to the rejuvenation of fracture repair. 3) Define how specific macrophage populations and the proteins they secrete alter mesenchymal differentiation in fracture repair. Our prior work showed an important role for beta-catenin in mesenchymal cell differentiation and in fracture repair rejuvenation. Here we will use in-vitro approaches to determine how specific subpopulations of macrophage cells and the proteins they secrete alter mesenchymal cell differentiation in cells from young and old animals. There will be an initial focus on beta-catenin, but an unbiased approach will be used as well. This proposed work builds on our prior studies of rejuvenation by heterochronic parabiosis in fracture repair. It will address critical gaps in our knowledge about the mechanism responsible for the rejuvenation phenotype driven by heterochronic parabiosis. Our work will also identify a novel therapeutic approach to address a critical clinical problem in older patients, delayed fracture healing.

随着年龄的增长，骨骼修复的速度减慢，增加了延迟愈合或不愈合的机会。 这些并发症通过外科手术治疗，导致显着的发病率甚至死亡率， 尤其是老年人。在这里，我们将利用异时性联体共生（其中两个 不同年龄的小鼠共享血液供应）表明，暴露于年轻的循环系统和年轻的小鼠中 巨噬细胞使老年小鼠的骨折修复恢复活力。在我们的初步数据中，我们使用了细胞谱系追踪 分析和共生实验以确定骨折修复中巨噬细胞的发育来源， 并发现它们源自卵黄囊来源的细胞亚群。有趣的是，这些细胞位于 脾脏并在骨修复过程中通过循环被招募。随着小鼠年龄的增长，这种细胞亚群 变得耗尽。在本提案中，我们研究了该细胞群的作用以及它们在细胞中产生的因子。 通过实现以下目标来振兴骨折修复： 1) 确定源自卵黄囊祖细胞的巨噬细胞在细胞再生中的作用 骨折修复。将研究异时性联体共生，其中这些细胞可以被标记或耗尽 确定巨噬细胞群中年轻细胞对提高质量的贡献 老年动物的骨折修复。 2) 确定在独特的巨噬细胞亚群中表达的基因的功能 骨修复中的年轻小鼠：我们使用单细胞 RNA 测序发现了一个独特的亚群 巨噬细胞仅存在于年幼动物的骨修复中。缺乏编码基因的小鼠 各种巨噬细胞群中的分泌蛋白将用于异时联体共生以确定 他们对骨折修复的复兴做出了贡献。 3) 定义特定的巨噬细胞群及其分泌的蛋白质如何改变 骨折修复中的间质分化。我们之前的工作表明 β-连环蛋白在 间充质细胞分化和骨折修复恢复活力。在这里，我们将使用体外方法 确定巨噬细胞的特定亚群及其分泌的蛋白质如何改变间充质 来自年轻和年老动物的细胞的细胞分化。最初将重点关注 β-连环蛋白，但 还将使用公正的方法。 这项拟议的工作建立在我们之前对骨折中异时联体共生的恢复研究的基础上 维修。它将弥补我们对复兴机制的认识中的关键空白 由异时性联体共生驱动的表型。我们的工作还将确定一种新的治疗方法 解决老年患者的一个关键临床问题：骨折延迟愈合。