Replicating heterochronic parabiosis on a chip for testing anti-geronic factors

项目总结 骨骼肌的功能和再生能力随着年龄的增长而下降，其中骨骼肌的丧失 质量归因于肌肉干细胞(卫星)细胞数量和功能的减少。再生能力不足 老龄化人口肌肉损伤后的反应进一步加剧了骨质疏松症的进展，并且 因此降低了独立性和生活质量。使用异慢性异种共生模型的激动人心的研究， 其中幼年和年老的动物通过手术连接到共享循环中，暗示着年轻的存在 循环中的因素可以修复因年龄增长而导致的肌肉再生缺陷。随后的研究发现 确定了几个系统性的促老年因素，但发现了作用于 肌肉干细胞恢复再生功能一直相对比较难以捉摸。在这方面，出现了 有证据表明，在出生后的生长和发育过程中，有一段时期的再生能力非常强 在有丝分裂后的细胞中保持可塑性。然而，确切的身份和潜在的促再生 人们对这一机制知之甚少。这些幼体保护因素可以表现为全身生长。 因子或以循环祖细胞的形式出现。这项提议的工作假设是，这些青少年 促再生因子随着年龄的增长而减少，这些因子在循环中的异位表达将诱导 对衰老的肌肉有卓越的年轻化效果。尽管有巨大的治疗前景，但关键的障碍是 限制了循环中假定的抗老年因子的检测是缺乏体外工具来概括 体内系统因素的动态调节。因此，从技术上讲，机械设计一直是一个挑战。 研究和阐明血源性因子对其靶组织的作用。为了克服这一挑战， 目标1的目的是设计一种新型的三维(3D)微流控芯片上的共生生物电路，该电路 利用天然肌肉微环境和体循环的关键特征。通过利用 具有体内验证和蛋白质组学的芯片上异种生物平台，这一创新系统将促进 检测新的体液因子和细胞，这些因素和细胞对异时性的返老还童起作用 异种共生。因此，目标2将解决是否通过以下方式暴露于老年肌肉中的幼年全身环境 异种复壮在体外和体内都有很好的复壮效果。计划中的成功结果 研究不仅在老年科学领域，而且在广泛的科学领域都将具有高度和广泛的影响。 片上共生电路将提供一种最先进的临床前测试工具，将有助于我们的 了解循环体液因子的动态调节，也可作为筛查 用于药物发现的设备。更重要的是，芯片上的异种生物可以扩展到研究其他器官系统。 并通过模拟人类芯片上的异种共生来进行人体临床研究 不能概括。

PROJECT SUMMARY Function and regenerative potential of skeletal muscle decline with age, where loss of skeletal muscle quality is attributed to reduced muscle stem (satellite) cell number and function. Inadequate regenerative response following muscle injuries in an aging population further exacerbate the progression of sarcopenia, and therefore reduced independence and quality of life. Exciting studies using the heterochronic parabiosis model, in which young and aged animals are surgically attached to share circulation, suggest the presence of youthful factors in the circulation can rejuvenate age-acquired deficits in muscle regeneration. Subsequent studies have identified a handful of systemic pro-geronic factors, but discovery of the humoral rejuvenation factors that act on muscle stem cells to restore regenerative function has been relatively more elusive. In this context, emerging evidence suggests that during postnatal growth and development, a period of exceptional regenerative capacity and plasticity are maintained in post-mitotic cells. However, the exact identity and underlying pro-regenerative mechanisms are poorly understood. These juvenile protective factors can be manifested as systemic growth factors or presented as circulating progenitor cells. The working hypothesis of this proposal is that these juvenile pro-regenerative factors decrease with aging and ectopic expression of these factors in circulation will elicit superior rejuvenation effects on aged muscle. Despite tremendous therapeutic promise, the critical barrier that limits the detection of putative anti-geronic factors in circulation is the lack of in vitro tools that recapitulates the dynamic regulation of systemic factors in vivo. Thus, it has been technically challenging to design mechanistic studies and elucidate the function of blood-borne factors on their target tissues. To overcome this challenge, the objective in aim 1 is to engineer a novel 3-dimensional (3D) microfluidic “parabiosis-on-a-chip” circuit that harnesses the key characteristics of native muscle microenvironment and systemic circulation. By leveraging parabiosis-on-a-chip platform with in vivo validation and proteomics, this innovative system will facilitate detection of novel humoral factors and cells that are responsible for rejuvenation effects in heterochronic parabiosis. As such, aim 2 will address whether exposure to the juvenile systemic milieu in aged muscle by parabiosis confers superior rejuvenation effects both in vitro and in vivo. Successful outcomes from proposed studies will have high and broad implications not only in Geroscience but also in broad scientific fields. Parabiosis-on-a-chip circuit will provide a state-of-the-art pre-clinical testing tool that will facilitate our understanding of the dynamic regulation of circulating humoral factors and can also be utilized as a screening device for drug discovery. More importantly, parabiosis-on-a-chip can be expanded to study other organ systems and translated into human clinical studies by emulating human parabiosis-on-a-chip that blood transfusion cannot recapitulate.