Impact of intracellular control over macrophage phenotype transitions on angiogenesis and wound healing

伤口愈合受损，就像糖尿病条件下的慢性伤口一样，是患者和经济卫生系统的主要负担。无法愈合的伤口的主要基础是长期的炎症状态和缺陷的血管生成。虽然巨噬细胞是炎症反应的关键参与者，已知它调节血管生成，但炎症受损导致血管生成受损背后的机制尚不清楚。此外，慢性创面显示促炎症M1型巨噬细胞出现延迟，促进愈合的M2巨噬细胞募集减少。然而，到目前为止，大多数研究只关注M2型巨噬细胞在伤口愈合和血管生成中的重要性，而主要没有考虑M1期对于它们出现的调节时间线的重要性。因此，延迟的M1的存在如何影响随后的M2巨噬细胞的到达和极化尚不清楚。因此，需要对这些过程进行深入研究，以设计基于巨噬细胞的功能性疗法作为疾病的治疗选择。斯皮勒博士团队的最新发现表明，在体外，从M1巨噬细胞直接过渡到M2型巨噬细胞(所谓的M1-M2巨噬细胞)的巨噬细胞比那些从未激活的M0巨噬细胞分化而来的巨噬细胞更容易血管生成，纤维化程度更低。在慢性创面中，这种M1-M2巨噬细胞类型的缺陷很可能是观察到的创面愈合缺陷的主要原因。因此，这个项目的首要目标是研究从M1型巨噬细胞向M2型巨噬细胞的转变如何影响正常和延迟愈合的血管生成过程。为了解决这个问题，将开发一种基于巨噬细胞的细胞治疗策略，其中被吞噬的微粒将用于在细胞内控制预极化的M1巨噬细胞向M2型巨噬细胞的转变。这一策略可能既可以增加巨噬细胞的数量，又可以保留其临界极化时间线。血管生成和血管生成的3D组织工程模型将在体外确定受控的M1-M2转变对血管形成和巨噬细胞-内皮细胞相互作用的影响。这一翻译策略将在糖尿病和野生型小鼠的皮肤创伤模型中进行体内评估。预计本研究中开发的生物材料介导的细胞治疗策略将有利于克服慢性创面愈合障碍和血管生成缺陷，通过增强促愈合和促血管生成的巨噬细胞表型，而不忽视重要的早期炎症反应。因此，该项目的结果将具有很高的临床意义。

Impaired wound healing, as in chronic wounds of diabetic conditions, is a major burden of patients and the economic health system. The primary underpinnings of non-healing wounds are a prolonged inflammatory state and defective angiogenesis. Although macrophages, key players of the inflammatory response, are known to regulate angiogenesis, the mechanisms behind how impaired inflammation leads to impaired angiogenesis are not understood. In addition, chronic wounds show a delayed appearance of macrophages of the pro-inflammatory M1 type as well as a diminished recruitment of pro-healing M2 macrophages. However, most studies so far focused only on the importance of M2 type macrophages in wound healing and angiogenesis, and majorly did not consider the importance of the M1 phase for the regulated timeline of their appearance. Thus, it is not known how the delayed M1 presence impacts the subsequent arrival and polarization of M2 macrophages. Therefore, in-depth studies of these processes are needed to enable the design of functional macrophage-based therapies as treatment options for diseases. Recent findings of Dr. Spiller’s group showed that macrophages that undergo a direct transition from M1 macrophages to the M2 type (so-called M1-M2 macrophages) were more angiogenic and less fibrotic than those which differentiated from unactivated M0 macrophages in vitro. In chronic wounds, the deficit of this M1-M2 macrophage type is most likely a major contributor to the observed defective wound healing. Therefore, the overarching goal of this project is to investigate how the transition from M1 to M2 type macrophages affects angiogenic processes in normal and delayed healing. To address this question, a macrophage-based cell therapy strategy will be developed in which engulfed microparticles will be utilized for intracellular control of the transition of pre-polarized M1 macrophages into the M2 type. This strategy may allow for both augmenting the macrophage population and retaining their critical polarization timeline. A 3D tissue-engineered model of vascularization and angiogenesis will determine the effects of the controlled M1-M2 transition on vessel formation and macrophage-endothelial cell interaction in vitro. This translational strategy will be evaluated in vivo in a cutaneous wound model in diabetic and wildtype mice. It is expected that the biomaterial-mediated cell therapy strategy developed in this study will be advantageous for overcoming impaired healing and defective angiogenesis in chronic wounds by augmentation of the pro-healing and pro-angiogenic macrophage phenotype without neglecting the important early inflammatory response. Therefore, the results of this project will be of high clinical relevance.