Studies of spontaneous regeneration in a novel amniote model

新型羊膜动物模型自发再生的研究

• 批准号: RGPIN-2014-04676
• 负责人: Vickaryous, Matthew
• 金额: $ 3.86万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=587948
• 关键词: Studies; spontaneous; regeneration; novel; amniote

Although most vertebrates are capable of replacing certain individual tissues, complete organ and appendage regeneration is rare. Among amniotes (reptiles + mammals), the most striking example is observed following tail loss in lizards. Unlike mammals, many lizard species are able to spontaneously regenerate the tail complete with a spinal cord, blood vessels, skeletal support and muscle. Using the lizard tail regeneration model, the LONG TERM GOAL of my research program is to identify and understand the biological mechanisms that permit and promote scar-free wound healing and tissue regeneration. Over the past 5 years, my NSERC funded research program has established that wound healing and regeneration in the lizard follows a highly conserved sequence of cellular and tissue-level events similar to those of other regenerating species. In addition, my lab has identified many of the key proteins involved in these events. I now propose to employ the lizard tail regeneration model to explore one of the most fundamental questions in regenerative biology: why some tissues, organs and species are capable of regenerating, whereas others cannot. I HYPOTHESIZE that regeneration requires a coordinated interaction between resident populations of stem/progenitor cells and a permissive wound environment. My SHORT TERM OBJECTIVES are to: (1) identify and track resident cells present in original tissues that contribute to the stem/progenitor pool following injury; and (2) determine the molecular factors and tissue-level characteristics of the wound healing environment that enable and promote regeneration. My proposed research program will employ a hierarchical and integrated approach, including: cell and tissue cultures; pharmacological, molecular and experimental manipulations of tissue within the regenerating tail; and the use of electroporation for labeling cells both in vitro and in vivo. For objective (1), my primary foci will be the spinal cord and axial skeleton. In lizards the spinal cord is continuous throughout the length of the tail. Loss of the tail results in the regeneration of a new spinal cord. Similarly, the axial skeleton is also regenerated. However, whereas the original skeleton is composed of bony vertebrae, the regenerated organ is an unsegmented cartilaginous cone that never ossifies. Presently, the original source and identity of cells contributing to the formation of these structures remains unknown. Experiments will include tracing studies (e.g., with fluorescent protein electroporation) to establish the source of cells from the original tissues into the regenerating tail. Other experiments will use explant cultures or, in the case of the spinal cord, generating neurospheres to screen for markers of stemness and neural/chondrogenic lineage. For objective (2), I will experimentally modulate the wound healing environment. Experiments will include altering the endogenous inflammatory response and modulating the transforming growth factor beta (TGFß)/activin signaling pathway. Conceptually, this ORIGINAL RESEARCH PROGRAM represents an INNOVATIVE approach to regenerative biology. Comparative studies involving regeneration-competent species provide unique opportunities to probe endogenous and naturally evolved mechanisms of tissue restoration. Lizards are one of the only amniotes capable of spontaneous multi-tissue regeneration. Lizards have evolved the ability to rapidly self-detach the tail as an anti-predation strategy. Structural adaptations of the tail minimize damage to adjacent tissues, and hence initiating regeneration is arguably less invasive than for other species. The entire tail can be repeatedly lost and regenerated (with functional recovery) without the need for clinical intervention.

尽管大多数脊椎动物能够替代某些个别组织，但完整的器官和附肢再生很少见。在羊膜动物(爬行动物+哺乳动物)中，最引人注目的例子是蜥蜴的尾巴消失。与哺乳动物不同，许多蜥蜴物种能够自发地再生尾巴，包括脊髓、血管、骨骼支撑和肌肉。使用蜥蜴尾巴再生模型，我的研究计划的长期目标是识别和理解允许和促进无疤痕伤口愈合和组织再生的生物机制。 在过去的5年里，我的NSERC资助的研究项目已经确定，蜥蜴的伤口愈合和再生遵循与其他再生物种相似的高度保守的细胞和组织水平事件序列。此外，我的实验室已经确定了参与这些事件的许多关键蛋白质。我现在建议使用蜥蜴尾巴再生模型来探索再生生物学中最基本的问题之一：为什么一些组织、器官和物种能够再生，而其他组织、器官和物种则不能。我假设，再生需要干细胞/祖细胞的常驻群体和允许的伤口环境之间的协调互动。我的短期目标是：(1)识别和跟踪损伤后原始组织中存在的有助于干细胞/祖细胞池的常驻细胞；(2)确定能够和促进再生的伤口愈合环境的分子因素和组织水平特征。 我提出的研究计划将采用分层和综合的方法，包括：细胞和组织培养；对再生尾巴内组织的药理学、分子和实验操作；以及使用电穿孔技术标记体外和体内的细胞。对于目标(1)，我的主要焦点将是脊髓和轴骨。蜥蜴的脊髓在整个尾巴长度内是连续的。失去尾巴会导致新脊髓的再生。同样，轴向骨架也会重新生成。然而，原始的骨骼是由骨性脊椎组成的，而再生的器官是一个不分段的软骨锥体，永远不会骨化。目前，参与这些结构形成的细胞的原始来源和身份尚不清楚。实验将包括示踪研究(例如，利用荧光蛋白电穿孔)，以确定从原始组织到再生尾巴的细胞来源。其他实验将使用外植体培养，或者在脊髓的情况下，生成神经球来筛选茎和神经/软骨血统的标记。对于目标(2)，我将实验性地调节伤口愈合环境。实验将包括改变内源性炎症反应和调节转化生长因子β(转化生长因子β)/激活素信号通路。 从概念上讲，这一原创研究计划代表了再生生物学的一种创新方法。涉及具有再生能力的物种的比较研究为探索组织修复的内生和自然进化机制提供了独特的机会。蜥蜴是仅有的能够自发多组织再生的羊膜动物之一。蜥蜴已经进化出快速自我分离尾巴的能力，作为一种反捕食策略。尾巴的结构适应性将对邻近组织的损害降至最低，因此启动再生可以说比其他物种的侵入性更小。整个尾巴可以反复丢失和再生(功能恢复)，不需要临床干预。