Mechanical programming to enhance the immunosuppressive function of mesenchymal stem cells for the treatment of graft-versus-host disease.

具体目标 间充质干/基质细胞（MSC）是免疫细胞的有效调节剂，并且它们的免疫抑制作用是通过免疫调节剂来实现的。 对于许多治疗应用，正在积极研究其功能。特别是， 证明MSC可以抑制效应性T细胞的增殖并诱导调节性T细胞 分化用于治疗移植物抗宿主病（GvHD）。一些MSC产品已通过 然而，MSC并不总是表现出一致的 在GvHD临床试验中的疗效。这部分是由于产生具有一致的、高表达的MSC的挑战。 治疗效能该项目的总体目标是开发MSC疗法， 通过鉴定和提供最佳微环境用于GvHD治疗的免疫抑制功效 MSC生产中的机械线索。来自细胞微环境的机械信号在 调节细胞行为。例如，研究表明，基质硬度指导细胞活性和命运 如迁移、增殖和分化。然而，基质或材料刚度仅描述其 静态、弹性力学性能。而不是简单的弹性，天然细胞外基质（ECM）和生活 组织是粘弹性的，在不同的特征时间尺度上表现出应力松弛（应力松弛在 不同的费率）。我们已经开发了一种水凝胶系统，可以概括的刚度和粘弹性 不同类型组织的行为。使用水凝胶作为培养基质，我们发现基质 除了刚度之外，应力松弛是调节细胞-ECM相互作用的重要机械因素 以及指导MSC活性，包括扩散、增殖、分化和体内骨再生。在 与FDA的Kyung Sung博士合作，我们最近发现基质应力松弛也调节 MSC的免疫抑制能力及其抑制T细胞增殖的能力;有趣的是，MSC保留了 它们的机械“记忆”甚至在从水凝胶中提取后也是如此（参见初步数据部分）。在 根据这些新发现，我们假设具有定制应力松弛特性的生物材料可以 在MSC生产中提供诱导机械信号以增强MSC的免疫抑制功效， GvHD治疗。我们将在以下具体目标中检验这一假设：目标1：阐明 基质应力松弛调节人骨髓间充质干细胞免疫抑制能力的机制 （hMSC）来源于骨髓。目的2：比较基质应力松弛对hMSCs体外诱导分化的影响 来自不同组织或通过整联蛋白表达分选的hMSC亚群。目的3：评价 用具有不同应力松弛特性的粘弹性水凝胶致敏的hMSCs用于GvHD治疗， 动物模型该项目使用多学科方法研究hMSC机械生物学。成功 这些目标的完成将对理解基质机械线索如何调节 hMSCs的免疫抑制能力，该发现可能导致更好的GvHD治疗。

SPECIFIC AIMS Mesenchymal stem/stromal cells (MSCs) are potent regulators of immune cells, and their immunosuppressive function is being actively investigated for a number of therapeutic applications. In particular, it has been demonstrated that MSCs can inhibit the proliferation of effector T cells and induce regulatory T-cell differentiation for treating graft versus host disease (GvHD). A few MSC products have been approved by regulatory agencies in countries outside of the U.S. However, MSCs have not always shown consistent efficacy in GvHD clinical trials. This is in part due to the challenges of generating MSCs with consistent, high therapeutic potency. The overarching goal of this project is to develop MSC therapies with enhanced immunosuppressive efficacy for GvHD treatment by identifying and providing optimal microenvironment mechanical cues in MSC production. Mechanical cues from cell microenvironment play important roles in regulating cell behavior. For example, studies have shown that matrix stiffness directs cell activity and fate such as migration, proliferation, and differentiation. However, matrix or material stiffness only describes their static, elastic mechanical property. Instead of being simply elastic, natural extracellular matrix (ECM) and living tissues are viscoelastic, exhibiting stress relaxation over different characteristic time scales (stress relaxes at different rates). We have developed a hydrogel system that can recapitulate the stiffness and viscoelastic behavior of different types of tissues. Using the hydrogels as culture substrates, we discovered that matrix stress relaxation, in addition to stiffness, is an important mechanical factor regulating cell–ECM interactions and directing MSC activities including spreading, proliferation, differentiation, and in vivo bone regeneration. In collaboration with Dr. Kyung Sung at FDA, we recently found that substrate stress relaxation also regulates MSC's immunosuppressive capacity and their ability to inhibit T cell proliferation; Interestingly, MSCs retained their mechanical “memory” even after being extracted from the hydrogels (see preliminary data section). In light of these new findings, we hypothesize that biomaterials with tailored stress relaxation properties can provide inducing mechanical cues in MSC production to enhance MSC's immunosuppressive efficacy for GvHD treatment. We will test this hypothesis in the following specific aims: Aim 1: Elucidate the molecular mechanisms by which matrix stress relaxation regulates the immunosuppressive capacity of human MSCs (hMSC) derived from bone marrow. Aim 2: Compare the effect of matrix stress relaxation on hMSCs derived from different tissues or hMSC subpopulations sorted by integrin expression. Aim 3: Evaluate the efficacy of hMSCs primed by viscoelastic hydrogels with different stress relaxation properties for GvHD treatment in an animal model. This project uses multidisciplinary approaches to study hMSC mechanobiology. Successful completion of these aims will have significant impact in understanding how matrix mechanical cues regulates the immunosuppressive capacity of hMSCs, with the findings potentially leading to better treatment for GvHD.