Does Inflammation Enhance Rengeneration?

描述（由申请人提供）：众所周知，持续的炎症会阻碍伤口修复的最佳目标，即以最小的疤痕迅速关闭伤口。然而，组织再生的目标（与伤口修复相反）是重建和替换受损组织，用失去组织的功能生物复制品而不留下疤痕。在后一种情况下，炎症的作用还没有很好地确定，原因很简单，包括人类在内的大多数哺乳动物很少表现出任何再生能力（肝脏除外），这就排除了实验方法。根据我们对附肢损伤小鼠模型（MRL小鼠耳孔闭合）的观察，该建议将解决反直觉的可能性，即增强炎症的至少某些方面将重新引导伤口愈合走向再生。我们还将研究使用新型生物材料来局部控制炎症反应的关键方面并促进组织再生。MRL小鼠已被证明是多种组织类型的强大再生者，我们一直注意到再生伴随着损伤部位强烈和长期的炎症。抗炎COX2抑制剂美洛昔康可抑制MRL耳孔闭合，提示炎症可能在功能上参与了附件再生。我们在非再生C57BL/6小鼠中直接测试了这种可能性，方法是将促炎药物咪喹莫特（一种toll样受体（TLR）配体）局部应用于两种伤口模型的损伤部位：耳孔愈合和手指截肢。在这两种情况下，都出现了积极的再生结果。在本提案中，我们将1)检查参与MRL再生反应的TLR， 2)尝试使用选择的TLR配体局部应用来刺激那些主要的TLR，以引发非再生C57BL/6小鼠的再生反应。炎症和再生反应的水平将在转录物、蛋白质、细胞和组织水平上决定。3)我们将这些TLR配体不仅局部应用，而且将生成化学偶联化合物到生物材料中。后者将为我们提供一种新型的可注射原位形成的大分子生物材料（NCL水凝胶），不仅可以用于表面损伤，也可以用于深部损伤。我们设想，这种模拟愈合伤口炎症微环境的方法将允许生物材料降解伴随着组织再生，从而在未来引领组织再生的新临床模式。

DESCRIPTION (provided by applicant): It is well known that prolonged inflammation hinders the optimal goal of wound repair, namely prompt closure of the wound with minimal scarring. However, the objective of tissue regeneration (as opposed to wound repair) is to reconstitute and replace damaged tissue with a functional biological replica of the lost tissue without scarring. In this latter case, the role of inflammation is not well established for the simple reason that most mammals including humans have rarely demonstrated any capacity for regeneration (with the exception of the liver) precluding experimental approaches. Based upon our observations in a mouse model of appendage injury (ear hole closure in the MRL mouse), this proposal will address the counter-intuitive possibility that enhancing at least some aspects of inflammation will re-direct wound healing towards regeneration. We will also examine the use of novel biomaterials to locally harness key aspects of the inflammatory response and facilitate tissue regeneration. MRL mice have been shown to be robust regenerators of multiple tissue types and we have consistently noted that regeneration is accompanied by intense and prolonged inflammation at the injury site. Administration of the anti-inflammatory COX2 inhibitor meloxicam inhibits MRL ear hole closure suggesting that inflammation may be functionally involved in appendage regeneration. We directly tested this possibility in non-regenerating C57BL/6 mice by topically applying the pro-inflammatory drug imiquimod, a toll-like receptor (TLR) ligand, to injury sites in two wound models: ear hole healing and digit amputation. In both cases, a positive regenerative result ensued. In this proposal, we will 1) examine the TLRs involved in the MRL regenerative response and 2) attempt to stimulate those predominant TLRs using select TLR ligands applied topically to elicit a regenerative response in the non-regenerating C57BL/6 mouse. The level of inflammation and regenerative response will be determined at the transcript, protein, cellular and tissue levels. 3) We will apply those TLR ligands not only topically but will generate chemically conjugated compounds to a biomaterial. The latter will provide us with a novel injectable in-situ forming macromolecular biomaterial (NCL hydrogel) that can be used for injuries that are not only surface injuries but deep injuries as well. We envision that this approach of mimicking the inflammatory microenvironment of a healing wound will allow for biomaterial degradation accompanied by tissue regeneration, leading in the future to new clinical modalities for tissue regeneration. PUBLIC HEALTH RELEVANCE: Achieving predictable regeneration of damaged tissues and organs is a major goal of medicine. By studying the remarkable ability of the MRL mouse to heal injuries and the role of inflammation in this process, we will gain insight into methods to help translate this knowledge into patient care. In particular, we will examine the role of implantable "smart" biomaterials that release regeneration-specific drugs under biological control.