How Does a Young Extracellular Matrix Rejuvenate Old Mesenchymal Stem Cells?

描述(由申请人提供)： 骨髓间充质干细胞(MSCs)具有自我更新和分化为多细胞系的能力。由于这些能力，间充质干细胞在大多数组织类型的持续维护和修复中发挥着重要作用。MSCs的数量和质量随着年龄的增长而减少，而这又与组织和器官功能的进行性衰竭有关。最近，我们在小鼠中报道了老年MSCs的自我更新和骨形成能力的缺陷可以通过暴露于幼年动物骨髓基质细胞产生的细胞外基质(ECM)而完全恢复，而当细胞(无论是来自幼年还是老年小鼠)被培养在由老年骨髓基质细胞产生的ECM上时，这种改善被显著减弱。这促使我们调查这种现象是否也发生在人类身上。事实上，我们在人类受试者中的初步研究清楚地表明，在年轻的骨髓基质细胞制造的ECM上培养老年MSCs能够提高它们的数量和质量。这项建议的目标是确定年轻的ECM使老年骨髓来源的MSCs恢复活力的机制。一种独特的无细胞ECM模型将被用来剖析年轻的ECM如何在体外和体内恢复老年MSCs的功能。本应用中提出的假设是，年龄对正常保留MSC功能的ECM的形成具有负面影响，而暴露于由年轻捐赠者的基质细胞制造的ECM可以改善老年MSCs的数量和质量。我们处于独特的地位，可以在人类身上测试这一假设，因为除了我们强大的初步数据外，在过去三年中，从老年人(60至96岁)那里收集了多达100份人类骨髓样本。为了验证这一假设，我们将系统地评估年轻和老年MSCs在病毒和体内的生物学活性(特定目标1)，并对暴露于年轻或老年ECM的年轻和老年MSCs进行蛋白质组学分析，以阐明与被拯救细胞恢复功能相关的蛋白质水平的潜在变化(特定目标2)。为了充分了解影响MSC行为的潜在机制，我们将确定年轻和老年ECM结构的差异，包括结构、机械性能和蛋白质组成(特定目标3)。这些研究具有创新性，因为我们将首次建立一个独特的VITR人体模型来研究年龄对MSCs的影响(内在理论)，以及周围ECM(外在理论)对MSCs的影响。从翻译的角度来看，我们的研究很重要，因为它们将提供关键信息，促进使用患者自己的(自体)干细胞进行基于细胞的治疗。鉴于老年人是这类治疗的MAI目标人群，低估MSCs和宿主的年龄相关性变化对于改善老年退伍军人自体MSCs移植的临床结果至关重要。

DESCRIPTION (provided by applicant): Bone marrow-derived mesenchymal stem cells (MSCs) are capable of self-renewal and differentiation into multiple cell lineages. Because of these capabilities, MSCs play an important role in continuous maintenance and repair of most tissue types. The quantity and quality of MSCs decrease with aging, which, in turn, is associated with the progressive failure of function of tissues and organs. Recently, we reported in mice that defects in the self-renewal and bone formation capacity of aged MSCs were completely restored by exposure to extracellular matrix (ECM) made by marrow stromal cells from young animals, and such improvement was substantially diminished when cells (from either young or old mice) were cultured on ECM made by old marrow stromal cells. This led us to investigate whether this phenomenon also occurs in humans. Indeed, our preliminary studies in human subjects clearly suggest that culturing aged MSCs on ECM made by young marrow stromal cells is able to improve their number and quality. The goal of this proposal is to determine the mechanisms whereby young ECM rejuvenates old bone marrow-derived MSCs. A unique, cell-free ECM model will be used to dissect how young ECM restores the functions of old MSCs in vitro and in vivo. The hypothesis proposed in this application is that age negatively impacts the formation of an ECM that normally preserves MSC function, and the quantity and quality of aged MSCs can be improved by exposure to an ECM made by stromal cells from young donors. We are uniquely-positioned to test this hypothesis in humans since, in addition to our strong preliminary data, up to 100 human bone marrow samples have been accumulated in the past three years from elders (60 to 96 years old). To test this hypothesis, we will systematically evaluate biological activities in viro and in vivo of young vs. old MSCs maintained on young- or old-ECM (Specific aim 1), and conduct proteomic analysis of young- and old-MSCs exposed to young- or old-ECM to elucidate the underlying changes at the protein level that are associated with the restored functions of the rescued cells (Specific aim 2). To fully understand the mechanisms underlying the influence of MSC behavior, we will determine the differences in the structures of young- vs. old-ECM including the architecture, mechanical properties, and protein composition (Specific aim 3). These studies are innovative in that we will have established, for the first time, a unique in vitr human model to examine effects of age on MSCs (intrinsic theory), and changes to MSCs by the surrounding ECM (extrinsic theory). Our studies are important from a translational point of view because they will provide key information that can facilitate the use of a patient's own (autologous) stem cells for cell- based therapies. In view of the fact that the elderly are the mai target population for this type of treatment, understating age-related changes in both MSCs and host is essential for improving the clinical outcome of transplanted autologous MSCs in old veteran.