Mechanism of Mitochondrial Dysfunction in Mesenchymal Stem Cells During Aging

描述(申请人提供)：本次K01奖项申请的目标是促进候选人Eliseev博士的职业发展。在Regis O‘Keefe、Matthew Hilton和Paul Brookes博士的指导下，候选人将阐明间充质干细胞(MSC)的生物能量学和成骨能力之间的联系，以及这一联系中与衰老有关的变化。这些研究将作为一种工具，将Eliseev博士引入对他来说是新的研究领域，如干细胞、骨骼重塑和修复、衰老、骨质疏松症和小鼠遗传模型。MSCs利用糖酵解产生能量，并在成骨分化过程中转换为线粒体氧化磷酸化。这种生物能量开关在衰老、糖尿病和其他疾病中被破坏，导致MSC成骨能力下降和骨质疏松。我们的长期研究目标是了解细胞新陈代谢如何决定细胞命运，以及如何为预防和治疗的目的而操纵它。这项建议的目的是确定MSC生物能量学在衰老过程中发生变化的机制及其对MSC成骨能力和骨质量的影响。线粒体通透性转变(MPT)的激活是心血管和其他系统在衰老过程中的一个有充分证据的事件。MPT在老年骨骼中的作用尚未阐明。基于我们的数据和文献，我们的中心假设是生物能量衰竭和MPT导致的活力下降破坏了老年MSCs的成骨能力，导致骨质疏松和骨折愈合延迟，这可以通过抑制MPT来逆转。我们的具体目标是：(1)明确老年MSCs线粒体功能障碍的机制及其对MSC活性和成骨能力的影响。我们假设MPT就是这样一种机制；(2)阐明MPT抑制衰老过程中骨质疏松的作用。我们假设这将改善老年小鼠的骨骼质量；以及(3)确定MPT对老年小鼠骨折愈合的抑制作用。我们假设这将加速骨折愈合。为了达到我们的目标，我们将使用MSC生物学方法；全球或MSC特异性MPT功能丧失的小鼠遗传模型；以及新型药理抑制剂。我们在这里的贡献是希望详细了解MSC生物能量学在衰老过程中是如何被破坏的，以及如何将其改进以达到预防和治疗的目的。这是非常重要的，因为它将导致骨质疏松症和骨折修复的新战略，并为公众健康提供重大好处。我们的研究还将通过阐明MSC生物能量学和成骨活性之间尚不清楚的机制来推动骨生物学和衰老领域的发展。我们的研究具有创新性，因为它脱离了现状，将骨髓间充质干细胞中受损的生物能量物质置于骨质疏松症发病机制的中心；并测试了一种新的方法-MPT抑制，以治疗骨质疏松症和衰老过程中骨折延迟愈合。

DESCRIPTION (provided by applicant): The goal of this K01 Award application is to enhance career development of the Candidate, Dr. Eliseev. Under the guidance of Drs. Regis O'Keefe, Matthew Hilton and Paul Brookes, the Candidate will elucidate the link between bioenergetics and osteogenicity of mesenchymal stem cells (MSC) and aging-related changes in this link. These studies will serve as a vehicle for introducing Dr. Eliseev into research areas that are new to him, such as stem cells, bone remodeling and repair, aging, osteoporosis, and mouse genetic models. MSCs use glycolysis for energy production and switch to mitochondrial oxidative phosphorylation during osteogenic differentiation. This bioenergetic switch is disrupted in aging, diabetes and other disorders leading to decreased MSC osteogenicity and osteoporosis. Our long-term research goal is to understand how cell metabolism determines cell fate and how it can be manipulated for the purposes of prevention and therapies. The objective of this proposal is to determine the mechanism underlying changes in MSC bioenergetics during aging and its effect on MSC osteogenicity and bone quality. Activation of the mitochondrial permeability transition (MPT) is a well documented event in cardiovascular and other systems during aging. The role of the MPT in aged bone has not been elucidated. Based on our data and the literature, our central hypothesis is that bioenergetic failure and decreased viability due to the MPT disrupt osteogenic potential of aged MSCs, leading to osteoporosis and delayed fracture healing that can be reversed by inhibition of the MPT. Our specific aims are: (1) determine the mechanism of mitochondrial dysfunction in aged MSCs and its effect on MSC viability and osteogenicity. We hypothesize that the MPT is such a mechanism; (2) elucidate the effect of inhibition of the MPT on osteoporosis during aging. We hypothesize that this will improve bone quality in aged mice; and (3) determine the effect of inhibition of the MPT on fracture healing in aged mice. We hypothesize that this will accelerate fracture healing. To attain our aims we will use MSC biology methods; mouse genetic models of global or MSC-specific loss-of-function of the MPT; and novel pharmacological inhibitors. Our contribution here is expected to be a detailed understanding of how MSC bioenergetics is disrupted in aging and how it can be improved for the purposes of prevention and therapies. This is very significant because it will lead to new strategies for osteoporosis and fracture repair and provide significant benefits for public health. Our research will also advance the field of bone biology and aging by elucidating yet unknown mechanisms connecting MSC bioenergetics and osteogenicity. Our research is innovative because it departs from the status quo and puts impaired bioenergetics in MSCs in the center of pathogenesis of osteoporosis; and tests a novel approach, MPT inhibition, to treat osteoporosis and delayed fracture healing during aging.