Nanofiber Scaffolds for Salivary Gland Regeneration

摘要 尽管细胞外基质（ECM）重塑是对损伤、过度ECM沉积或纤维化的自然反应， 限制再生，是数百种疾病的致病因素，并导致全球40%的死亡。纤维化 发生在头颈癌放射治疗患者的唾液腺（SG）中， 自身免疫性疾病，干燥综合征（SS）。尽管已知纤维化对组织再生的抑制作用， 以及疾病中纤维化的参与，纤维化在唾液腺中发展并导致 功能障碍尚未被探索。唾液腺和其他器官的基质包括组织驻留间充质细胞， 干细胞（MSC）。MSC具有固有的抗纤维化和抗炎功能;然而，在疾病状态下， 驻留的MSC可经历转化成肌成纤维细胞（myo-FB）并促成纤维化。治疗 MSC的移植已被用于治疗许多炎性疾病，其中最常见的组织来源用于 治疗性MSC是骨髓（BM）。将BM-MSC注射到非肥胖糖尿病（NOD）小鼠中， 使用SS小鼠模型，显示炎症减少和一些有限的SG功能恢复;然而， 是短暂的，导致功能恢复的机制仍然未知。操纵内源性的疗法 或应用外源性MSCs治疗纤维化和唾液腺功能减退等疾病。机制 组织驻留的MSC和移植的MSC在SG中通过何种途径成为纤维化产生的肌纤维母细胞是未知的; 然而，在许多组织中，需要Gli 1的信号传导。我们假设，组织驻留的MSC， 转化为肌纤维母细胞，导致纤维化结缔组织，加重自身免疫性疾病和唾液功能障碍。 该提案的目的是确定组织驻留MSC的调节是否可以限制纤维化、炎症和炎症。 恢复受损和患病唾液腺的腺体功能。我们将讨论几个重要的临床相关 本提案中的问题：1）Gli 1信号是否有助于损伤/患病唾液腺的纤维化？2)纸巾- 常驻肌纤维母细胞恢复到亲再生MSC状态，以及区分这种状态的相关遗传变化是什么 皈依？3)在小鼠舍格伦综合征模型中，将限制组织驻留MSC转化为肌纤维母细胞 限制纤维化，减少疾病进展，促进功能恢复？我们拟议研究的结果是 有望通过揭示MSC促进纤维化的细胞机制来提高科学知识， SG.这些发现将通过确定潜在的治疗靶点产生积极的影响。此外，我们还将优化 用于MSC和抗纤维化药物的支架递送系统，用于减少纤维化和恢复功能， 唾液腺和其他器官功能减退。

ABSTRACT Although extracellular matrix (ECM) remodeling is a natural response to injury, excessive ECM deposition, or fibrosis, limits regeneration, is a causative factor in hundreds of diseases, and leads to 40% of all deaths worldwide. Fibrosis occurs in salivary glands (SG) of patients treated with radiation for head and neck cancers and in patients suffering from the autoimmune disease, Sjögren’s Syndrome (SS). Despite the known inhibitory effects of fibrosis on tissue regeneration, and involvement of fibrosis in disease, the mechanisms through which fibrosis develops in the salivary gland and leads to dysfunction have not been explored. The stroma of salivary glands and other organs includes tissue-resident mesenchymal stem cells (MSCs). MSCs have inherent anti-fibrotic and anti-inflammatory functions; however, in disease states tissue- resident MSCs can undergo conversion into myofibroblasts (myo-FBs) and contribute to fibrosis. Therapeutic transplantation of MSCs has been used to treat many inflammatory disorders, with the most common tissue source for therapeutic MSCs being bone marrow (BM). Injection of BM-MSCs into non-obese diabetic (NOD) mice, a commonly used mouse model for SS, showed decreased inflammation and some limited SG functional restoration; however, effects were transient and the mechanisms leading to restored function remain unknown. Therapies that manipulate endogenous or apply exogenous MSCs hold clinical promise for diseases involving fibrosis and salivary hypofunction. Mechanisms through which tissue-resident MSCs and transplanted MSCs become fibrosis-generating myo-FBs in the SG are unknown; however, in many tissues signaling by Gli1 is required. We hypothesize that tissue-resident MSCs that undergo conversion to myo-FBs leading to fibrotic connective tissue exacerbating autoimmune disease and salivary dysfunction. The objective of this proposal is to determine if modulation of tissue-resident MSCs can limit fibrosis, inflammation, and restore gland function in injured and diseased salivary glands. We will address several important clinically relevant questions in this proposal: 1) Does Gli1 signaling contribute to fibrosis in injured/diseased salivary glands? 2) Can tissue- resident myo-FBs revert to a pro-regenerative MSC state and what are the associated genetic changes that demark this conversion? 3) In a murine Sjögren’s Syndrome model, will limiting conversion of tissue-resident MSCs into myo-FBs limit fibrosis, decrease disease progression, and facilitate functional restoration? The outcomes of our proposed study are expected to improve scientific knowledge by revealing cellular mechanisms through which MSCs contribute to fibrosis in SG. These findings will have a positive impact by identifying potential therapeutic targets. In addition, we will optimize scaffold delivery systems for MSCs and anti-fibrotic pharmacologicals for reducing fibrosis and restoring function in hypofunctioning salivary glands and other organs.