Fate and Regulation of Fracture-induced Prx1 Cells

骨折诱导的 Prx1 细胞的命运和调控

• 批准号: 10649689
• 负责人: Anna Spagnoli
• 金额: $ 34.24万
• 依托单位: RUSH UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-25 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10649689
• 关键词: AMD3100; Ablation; Achievement; Adult; Affect; Alternative Therapies; Animal Model; Attention; Autologous Transplantation; Automobile Driving; Bone Morphogenetic Proteins; CXC Chemokines; CXCR4 gene; Cell Therapy; Cell Transplantation; Cells; Clinical; Clinical Trials; Complement; Development; Disease; Ensure; Forearm Fracture; Foundations; Fracture; Gene Silencing; Generations; Genes; Genetically Engineered Mouse; Goals; Hip Fractures; Impairment; In Vitro; Knockout Mice; Knowledge; Lead; Life; Ligands; Limb structure; Molecular; Mus; Natural regeneration; Nature; Operative Surgical Procedures; Patients; Pattern; Pericytes; Persons; Pharmacology Study; Pharmacotherapy; Phenotype; Population; Process; Regulation; Reporting; Research; Research Personnel; Role; Signal Transduction; Spinal Fractures; Stromal Cell-Derived Factor 1; Testing; Time; Transplantation; United States; antagonist; bone; bone fracture repair; cardiovascular disorder risk; clinically relevant; clinically significant; conditional knockout; cost; cytokine; design; genetic approach; healing; in vivo; lifetime risk; new therapeutic target; novel; novel therapeutics; osteoprogenitor cell; pharmacologic; postnatal; progenitor; public health relevance; receptor; regenerative; repaired; reparative process; skeletal; standard care; stem cells; therapeutic target; transcription factor; transcriptome

PROJECT SUMMARY Fracture healing is a well-orchestrated regenerative process that remains largely unknown. Revealing the cellular and molecular mechanisms governing fracture repair will help identify novel therapeutic targets to treat patients that suffer of non-unions, a clinically relevant problem that affects annually 600,000 people in the United States. Bone autografts, the gold-standard treatment for non-unions, have multiple drawbacks: they are invasive, costly, risky, and sometime ineffective. Therefore, there is an urgent and unmet need for alternative and novel therapies to treat non-unions. The ultimate goal of this proposal is to gain new knowledge on pivotal mechanisms driving fracture repair and to devise them to promote healing. The highly regenerative ability of bones after fracture implies the existence of adult progenitors that contribute to the reparative process. However, the nature and the expression pattern of these progenitors is still elusive. We have discovered a discrete population of perivascular cells expressing Prx1 (Prx1+) that reside in recognized regenerative niches. By investigating functionality, we have found that facture elicits Prx1expression and Prx1+ expressing cells that contribute to the fracture repair process, but cells lose Prx1 expression with differentiation. We have also found that during fracture repair, Prx1+ cells co-express BMP2 and CXCL12. On the way to further explore this crosstalk, we discovered that the impaired fracture healing found in mice lacking a full complement of BMP2 in Prx1 osteochondroprogenitors, was characterized by an abnormally persistent increase of Prx1 and the cytokine CXCL12. These abnormalities were corrected by AMD3100, a CXCL12 receptor antagonist that restored healing. Lastly, by using in vivo and in vitro approaches, we have indicated that BMP2 through CXCL12 signaling regulates Prx1 expression. Current knowledge and these exciting novel observations set the scientific premise to the central hypothesis of this proposal, namely that Prx1 expressing cells are a crossroad in fracture repair and their commitment to regeneration and their Prx1 expression pattern is regulated by a well-timed interplay between BMP2 and CXCL12. Two specific aims are proposed to test this novel hypothesis. Aim 1 is designed to determine the requirement of Prx1 and Prx1 expressing cells and their fate and nature during fracture repair. Aim 2 is designed to determine the mechanisms by which the expression of Prx1 and the fate of Prx1+ cells is regulated by the interplay between BMP2 and CXCL12 during fracture repair. A comprehensive approach will be applied to accomplish the proposed aims, by combining generation of ad hoc genetically engineered mice; cell-tracing; educated use of animal models; pharmacological and cell transplant studies; and in vitro studies. A team of expert research investigators has been assembled to ensure successful achievement of the project. It is expected that the novel findings generated from this research will have major biomedical relevance and implications for: a) understanding the cellular and molecular mechanisms governing fracture healing; and b) laying the groundwork for the development of pharmacological and cell-based clinical trials to treat non-unions.

项目概要 骨折愈合是一个精心策划的再生过程，但在很大程度上仍然未知。揭示细胞 骨折修复的分子机制将有助于确定新的治疗靶点来治疗患者 患有骨不连的患者，这是一个与临床相关的问题，每年影响美国 60 万人。 自体骨移植是骨不连的金标准治疗方法，但它有多种缺点：它们是侵入性的、成本高昂、 有风险，有时甚至无效。因此，对替代和新型疗法的需求迫切且未得到满足 治疗非工会。该提案的最终目标是获得有关驱动关键机制的新知识 骨折修复并设计它们以促进愈合。骨折后骨骼的高度再生能力 意味着成年祖细胞的存在有助于修复过程。然而，大自然和 这些祖细胞的表达模式仍然难以捉摸。我们发现了血管周围的离散群体 表达 Prx1 (Prx1+) 的细胞位于公认的再生生态位中。通过研究功能，我们 发现骨折会引发 Prx1 表达和 Prx1+ 表达细胞，有助于骨折修复 过程中，但细胞会随着分化而失去 Prx1 表达。我们还发现，在骨折修复过程中，Prx1+ 细胞共表达 BMP2 和 CXCL12。在进一步探索这种串扰的过程中，我们发现 Prx1 骨软骨祖细胞中缺乏 BMP2 的小鼠中发现骨折愈合受损， 其特征是 Prx1 和细胞因子 CXCL12 异常持续增加。这些异常 已被 AMD3100 纠正，AMD3100 是一种 CXCL12 受体拮抗剂，可恢复愈合。最后，通过使用体内和 在体外方法中，我们表明 BMP2 通过 CXCL12 信号传导调节 Prx1 表达。当前的 知识和这些令人兴奋的新颖观察为中心假设奠定了科学前提 该提议，即 Prx1 表达细胞是骨折修复及其承诺的十字路口 再生及其 Prx1 表达模式受 BMP2 之间适时相互作用的调节 和CXCL12。提出了两个具体目标来检验这一新假设。目标 1 旨在确定 骨折修复过程中 Prx1 和 Prx1 表达细胞的需求及其命运和性质。目标2已设计 确定 Prx1 的表达和 Prx1+ 细胞的命运受 骨折修复过程中 BMP2 和 CXCL12 之间的相互作用。将采用综合方法 通过结合特设基因工程小鼠的产生来实现拟议的目标；细胞追踪； 有根据地使用动物模型；药理学和细胞移植研究；和体外研究。一个团队 已召集了专家研究人员以确保该项目的成功实现。这是 预计这项研究产生的新发现将具有重大的生物医学相关性，并且 对以下方面的影响： a) 了解控制骨折愈合的细胞和分子机制；和 b) 为治疗骨不连的药理学和细胞临床试验的发展奠定基础。