The Interplay between Macrophages and Differentiating MSCs in Cell-Laden Hydrogel

描述（由申请人提供）：本提案的总体目标是更好地了解异物反应（FBR）在组织工程中的作用，特别是询问巨噬细胞和支架内细胞之间的动态相互作用。虽然已经针对包括用于组织工程的支架的可植入生物医学材料研究了FBR，但是还没有研究FBR对驻留在支架上的细胞的影响。 已经解决了。我们的初步研究提供了两个重要的观察结果：1）在询问巨噬细胞（FBR的主要协调者）和包裹的细胞之间存在动态通信，其影响整体响应（FBR和新组织形成两者）和2）FBR的严重程度似乎取决于包裹的细胞的分化阶段。根据这些观察，我们提出了以下假设，供本提案检验。具体来说，我们将测试的假设，炎症巨噬细胞阻碍生物可降解水凝胶封装的细胞的生物合成能力，但间充质干细胞（MSC）和分化的MSC改变巨噬细胞表型，并改善工程组织的整体结果。为了验证这一假设，我们已经开发了两个具体的目标：目标1）我们将确定在可生物降解的PEG基水凝胶中的包封细胞的分化阶段是否影响询问巨噬细胞的活化，并进而影响包封细胞。目的2）我们将评估当包封处于不同分化阶段的细胞时，载有细胞的可生物降解的基于PEG的水凝胶的体内性能。为了实现我们提出的目标，我们将开发一种用于骨组织工程的组织工程模型系统，其中在成骨分化的不同阶段的MSC被封装在骨仿生水凝胶中。在目标1中，我们将使用我们建立的体外共培养模型，该模型模拟巨噬细胞在炎症环境中询问载有细胞的水凝胶，以阐明包囊细胞和巨噬细胞之间的动态相互作用。在目标2中，我们将使用同基因细胞负载水凝胶植入免疫活性动物皮下，以阐明封装的细胞和复杂的FBR之间的动态相互作用。通过了解不同分化阶段的询问巨噬细胞和包囊细胞之间的动态相互作用，我们有可能确定分化（新组织形成所需）和抗炎特性（以降低FBR的严重程度）之间的平衡，我们假设这两者将导致长期显着改善新组织生长。

DESCRIPTION (provided by applicant): The overall goal of this proposal is to better understand the role of the foreign body reaction (FBR) in tissue engineering and in particular the dynamic interplay between interrogating macrophages and the cells residing within a scaffold. While the FBR has been investigated with respect to implantable biomedical materials including scaffolds for tissue engineering, the impact of the FBR on cells residing with the scaffold has not been addressed. Our preliminary studies have provided two important observations: 1) there exists a dynamic communication between interrogating macrophages (the primary orchestrators of the FBR) and the encapsulated cells which impacts the overall response (both FBR and neotissue formation) and 2) the severity of the FBR appears to depend on the differentiation stage of the encapsulated cell. Based on these observations we have formulated the following hypothesis to be tested in this proposal. Specifically, we will test the hypothesis that inflammatory macrophages hinder the biosynthetic ability of cells encapsulated in biodegradable hydrogels but mesenchymal stem cells (MSCs) and differentiating MSCs alter macrophage phenotype and improve the overall outcome of the engineered tissue. To test this hypothesis we have developed two specific aims: Aim 1) We will determine whether the stage of differentiation of encapsulated cells in biodegradable PEG-based hydrogels affects the activation of interrogating macrophages and in turn influences the encapsulated cells. Aim 2) We will evaluate the in vivo performance of cell-laden biodegradable PEG-based hydrogels when cells at different stages of differentiation are encapsulated. To accomplish our proposed aims, we will develop a tissue engineering model system for bone tissue engineering where MSCs at varying stages of osteogenic differentiation are encapsulated in a bone biomimetic hydrogel. In Aim 1, we will use our established in vitro co-culture model, which simulates macrophages interrogating a cell-laden hydrogel in an inflammatory environment to elucidate the dynamic interplay between encapsulated cells and macrophages. In Aim 2, we will use syngeneic cell-laden hydrogels implanted subcutaneously in immumocompetent animals to elucidate the dynamic interplay between encapsulated cells and the complex FBR. By understanding the dynamic interplay between interrogating macrophages and encapsulated cells at different stages of differentiation, we have the potential to identify a balance between differentiation (required for neotissue formation) and anti-inflammatory properties (to reduce the severity of the FBR), which together we hypothesize will lead to significantly improved neotissue growth long-term.