New class of collagen-targeted contrast agents for Magnetic Resonance Imaging

项目摘要 慢性肝病是世界范围内死亡率上升最快的主要原因之一。慢性肝病 疾病是多因素的，可由病毒性肝炎感染到酒精等损害引起 滥用到糟糕的饮食。导致这些疾病的是流行的非酒精性脂肪性肝炎(NASH)，但所有慢性肝脏 如果不加以控制，疾病会发展为肝纤维化。肝纤维化可以在有效的治疗后消退，但在离开时 未经治疗的肝纤维化可能会发展为肝功能衰竭或肝癌。准确的诊断、分期和监控 肝纤维化的防治是慢性肝病患者治疗的关键。目前的诊断护理标准 而肝纤维化的分期是活检，这有发生内出血的风险，只有一小部分样本 肝脏，并遭受观察者间的变异性。 纤维化期，而不是脂肪变性或炎症，是疾病的唯一特征，与病情恶化有关 纳什的结果。除了活检之外，我们还缺乏良好的工具来无创地检测肝纤维化、分期纤维化或 监测对治疗的反应。弹性成像方法对疾病的早期变化不敏感。血清 用于识别NASH和/或肝纤维化的生物标记物和生物标记物面板也是有限的，并且缺乏准确性 准备好了。这些技术都没有监测治疗的准确性。一种准确、安全的诊断方法 监测NASH及其相关的纤维化在临床实践和临床研究中都具有极其重要的意义。 胶原蛋白医学公司开发了I型胶原结合肽(CBP)，并将其连接到Gd螯合物上 用于肝纤维化的无创性MRI分期。这些探针(EP-3533和CM-101)被静脉注射， 与纤维化肝脏的结合与纤维化程度成正比，而未结合的探针则迅速被肾脏消除。 尽管低剂量(5-10微克分子/公斤)的探针在多种动物模型中有效，但预期的商品成本 在这个剂量下，预计太高，不能在商业上可行。 这项第一阶段的SBIR提案旨在通过以下方式降低胶原靶向磁共振成像探头的产品成本 将胶原蛋白医疗公司的CBP技术与超小的氧化铁纳米颗粒(ESPION)相结合 麻省理工学院开发的技术。ESTON在T1加权MRI扫描中提供强烈的阳性对比，很小 足以从血管中渗出，并通过肾滤过被清除。电子的松弛系数为5。 -比CM-101高20倍。较高的弛豫度应该等同于较低的剂量，我们假设 Espion-CBP结合物在剂量比CM-101低5-20倍时同样有效，因此显著 更低的商品成本。此外，可以从廉价的原材料中制备ESTON，而合成ESPONE 先前与CBP偶联的双功能Gd-螯合物需要多个合成步骤 和昂贵的层析提纯。我们的方法是合成一个小的espion-CBP文库 结合物和筛选的松弛，胶原结合亲和力，胶原特异性，和代谢稳定性在体外。 然后，我们将展示我们的主要espion-CBP结合物能够通过以下方式可视化肝纤维化 在小鼠体内对先前研究的基于Gd的胶原靶向探针CM-101具有更高的检测灵敏度 肝纤维化模型。

Project Summary Chronic liver disease is one of the leading and most rapidly rising causes of mortality worldwide. Chronic liver disease is multifactorial and can be brought upon from damages ranging from viral hepatitis infection to alcohol abuse to poor diet. Leading these is the epidemic of nonalcoholic steatohepatitis (NASH), but all chronic liver diseases progress to liver fibrosis if unchecked. Fibrosis may resolve following effective treatment, but when left untreated liver fibrosis can progress to liver failure or liver cancer. Accurate diagnosis, staging, and surveillance of liver fibrosis is key to chronic liver disease patient management. The present standard of care for diagnosis and staging of liver fibrosis is biopsy, which runs the risk of internal bleeding, samples only a small portion of liver, and suffers from interobserver variability. Fibrosis stage, and not steatosis nor inflammation, is the only feature of disease associated with worse outcomes in NASH. Besides biopsy we lack good tools to noninvasively detect liver fibrosis, stage fibrosis, or monitor response to treatment. Elastography methods are not sensitive to early changes in disease. Serum biomarkers and biomarker panels to identify NASH and/or liver fibrosis, are also limited and lack accuracy for staging. None of these techniques has the accuracy to monitor treatment. An accurate, safe method to diagnose and monitor NASH and associated fibrosis is of utmost importance in both clinical practice and clinical research. Collagen Medical has developed type I collagen-binding peptides (CBP) conjugated to gadolinium chelates for noninvasive MRI staging of liver fibrosis. These probes (EP-3533 and CM-101) are injected intravenously, binding to fibrotic liver in proportion to the degree of fibrosis, while the unbound probe is rapidly renally eliminated. Despite efficacy in multiple animal models at low doses of probe (5 – 10 µmol/kg), the anticipated cost of goods at this dose is expected to be too high to be commercially viable. This Phase I SBIR proposal seeks to reduce the cost of goods of a collagen-targeted MR imaging probe by combining Collagen Medical’s CBP technology with exceedingly small iron-oxide nanoparticle (ESPION) technology developed at MIT. ESPIONs provide strong positive contrast in T1-weighted MRI scans, are small enough to extravasate from blood vessels, and are eliminated via renal filtration. The relaxivity of ESPIONs is 5 – 20 times higher than CM-101. A higher relaxivity should equate to a lower dose and we hypothesize that an ESPION-CBP conjugate would be as effective at a 5 – 20 fold lower dose than CM-101, and thus a significantly lower cost of goods. Furthermore, ESPIONs can are prepared from cheap raw materials whereas synthesis of the bifunctional Gd-chelates that have been previously conjugated to the CBP require multiple synthetic steps and costly chromatographic purification. Our approach is to synthesize a small library of ESPION-CBP conjugates and screen for relaxivity, collagen-binding affinity, collagen specificity, and metabolic stability in vitro. We will then demonstrate that our lead ESPION-CBP conjugate is capable of visualizing liver fibrosis with superior detection sensitivity to the previously studied Gd-based collagen-targeting probe CM-101 in a murine model of liver fibrosis.