Removal of Senescent Cells for Adipose-derived Stem Cell Transplants

描述(申请人提供)：成人干细胞移植是一种新兴的治疗策略，具有广泛的潜力来治疗许多与年龄相关的疾病，如心血管疾病、糖尿病和神经退行性疾病。然而，很少有研究探索干细胞移植在老年人群中疗效降低的原因，他们可能从这些新的治疗策略中获益最多。我们的实验室正在使用“种子与土壤”模型来解决这个问题，询问是否移植细胞中的固有功能障碍，即“种子”，或不适宜居住的老化宿主微环境，即“土壤”，是否导致治疗潜力降低。我们特别感兴趣的是衰老细胞在移植的“种子”和“土壤”之间的相互作用中所起的作用。衰老 细胞是生长受阻的细胞，保持代谢活性，并通过分泌各种细胞因子、生长因子和基质重塑因子来促进促炎环境，统称为衰老相关分泌表型(SASP)。随着年龄的增长，全身衰老的细胞数量会增加，这被认为是导致许多与年龄相关的疾病的原因。因此，这项研究的长期目标是确定衰老细胞负荷增加在移植失败中的作用。我们的假设是，无论是从供体细胞还是从受体小鼠身上移除衰老细胞都将改善移植结果。我们还假设，通过使用被证明可以限制SASP的药物，即雷帕霉素和Janus激活的激酶(JAK)抑制剂，我们可以限制衰老细胞的有害影响，并改善移植结果。为了验证这些假设，我们将追求以下具体目标：目标1.土壤：通过去除受体小鼠衰老的细胞来准备移植微环境。目的2.种子：从供体ADSCs中去除衰老细胞，为移植细胞做好准备。目的3.药物干预：确定受者SASP抑制对自体ADSC移植疗效的影响。在这些研究中，我们将使用一种新的小鼠模型，在该模型中，可以通过给药一种不影响正常细胞的药物来选择性地清除小鼠体内的衰老细胞。我们将研究脂肪干细胞在小鼠皮肤伤口上的移植，以便轻松跟踪干细胞植入和整合到再生组织中，以及伤口闭合。在脂肪干细胞移植之前，将从接受者身上清除衰老细胞，为移植准备宿主环境(土壤)，或者在干细胞分离之前，从小鼠身上清除衰老细胞，以准备 移植的细胞(种子)。或者，受体动物在移植前将接受SASP限制剂雷帕霉素或JAK抑制剂治疗。这些实验的时间表可以在本提案的研究战略部分的末尾找到。我们对衰老细胞在干细胞移植中的作用的洞察可能对开发新的治疗策略非常有益，这些治疗策略允许将新兴的干细胞技术应用于老年人口。

DESCRIPTION (provided by applicant): Adult stem cell transplantation is an emerging therapeutic strategy with wide potential to treat numerous age-related disorders such as cardiovascular disease, diabetes, and neurodegenerative disease. However, very little research has explored the causes of decreased efficacy of stem cell transplantation in the elderly population, who may have the most to gain from these new therapeutic strategies. Our laboratory is attacking this question using a 'seed vs. soil' model, asking whether an inherent dysfunction in the transplanted cells, the 'seed', or an inhospitable aged host microenvironment, the 'soil', is responsible for decreased therapeutic potential. We are specifically interested in te role of senescent cells in this interaction between 'seed' and 'soil' in transplantation. Senescent cells are growth-arrested cells that remain metabolically active and have been shown to promote a pro-inflammatory environment through the secretion of various cytokines, growth factors, and matrix remodeling factors, collectively known as the senescence-associated secretory phenotype (SASP). With aging, senescent cell numbers increase throughout the body, and are thought to contribute to many age-related diseases. Therefore, the long term goal of this study is to determine the role of increasing senescent cell burden in transplant failure. Our hypothesis is that removal of senescent cells from either the donor cells or the recipient mouse will improve transplant outcomes. We also hypothesize that by using pharmacologic agents shown to limit the SASP, namely rapamycin and Janus-activated kinase (Jak) inhibitors, we can limit the detrimental effects of senescent cells and improve transplant outcomes. To test these hypotheses, we will pursue the following specific aims: AIM 1. Soil: Prepare the transplant microenvironment by removing senescent cells in recipient mice. AIM 2. Seed: Prepare the cells to be transplanted by removing senescent cells from donor ADSCs. AIM 3. Pharmacologic Intervention: Determine the effect of SASP inhibition in the recipient on efficacy of autologous ADSC transplant. In these studies, we will use a novel mouse model in which senescent cells can be selectively cleared from the mouse by administration of a drug that does not affect normal cells. We will study the transplantation of adipose-derived stem cells on skin wounds in mice, allowing easy tracking of stem cell engraftment and incorporation into regenerating tissue, as well as wound closure. Senescent cells will be cleared either from the recipient prior to transplantation of adipose-derived stem cells, to prepare the host environment (the 'soil') for transplant, or senescent cells will be cleared from mice before isolation of stem cells, to prepare the transplanted cells (the 'seed'). Alternatively, recipient animals will be treated with SASP-limiting agents rapamycin or Jak inhibitors prior to transplantation. A timeline for these experiments can be found at the end of the Research Strategy section of this proposal. The insights we gain into the role of senescent cells in stem cell transplantation may be hugely beneficial to the development of new therapeutic strategies that allow the application of emerging stem cell technologies to the elderly population.