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

具体目标 间充质干细胞(MSCs)是免疫细胞的强大调节者，其免疫抑制作用 目前正在积极研究其在多种治疗应用中的作用。特别是，它一直是 骨髓间充质干细胞可抑制效应T细胞的增殖并诱导调节性T细胞 移植物抗宿主病(GvHD)辨证论治少数MSC产品已通过 美国以外国家的监管机构。然而，MSCS并不总是表现出一致的 GvHD临床试验中的疗效。这在一定程度上是由于生成一致、高质量的MSCs所面临的挑战 治疗效果。该项目的总体目标是开发具有增强功能的MSC疗法 识别和提供最佳微环境对GvHD治疗的免疫抑制效果 MSC制作中的机械提示。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，基质硬度决定了细胞的活动和命运 如迁移、增殖和分化。然而，矩阵或材料的刚度仅描述了它们的 静态的、弹性的机械性能。天然的细胞外基质(ECM)不是简单的弹性，而是活的 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，它可以概括出刚性和粘弹性 不同类型组织的行为。利用水凝胶作为培养底物，我们发现基质 除刚性外，应力松弛也是调节细胞-细胞外基质相互作用的重要力学因素。 并指导MSC的活动，包括扩散、增殖、分化和体内骨再生。在……里面 与FDA的Kyung Sung博士合作，我们最近发现底物应力松弛也调节 MSC的免疫抑制能力及其抑制T细胞增殖的能力；有趣的是，MSCs保留了 即使在从水凝胶中提取出来后，它们的机械“记忆”也是如此(见初步数据部分)。在……里面 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线索以增强MSC的免疫抑制效果 GVHD治疗。我们将在以下具体目标中检验这一假说：目标1：阐明分子 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人骨髓间充质干细胞的影响 从不同的组织或hMSC亚群按整合素表达排序。目的3：评价安慰剂的疗效 不同应力松弛特性的粘弹性水凝胶诱导的人骨髓间充质干细胞治疗移植物抗宿主病 动物模型。该项目使用多学科方法来研究hMSC机械生物学。成功 这些目标的完成将对理解矩阵机械提示如何调节产生重大影响 HMSCs的免疫抑制能力，这一发现可能有助于更好地治疗GvHD。

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.