Characterizing mechanisms of sickle cell crisis via dynamic optical assay

描述（由申请人提供）：镰状细胞病（SCD），以纯合子形式称为镰状细胞贫血，影响50个非洲裔美国人中的1个，具有衰弱、慢性、危象发作和预期寿命缩短。SCD是一种遗传性血液疾病，由β-珠蛋白基因的单点突变引起。镰状血红蛋白（HbS）具有在脱氧时聚合的独特性质，从而触发红细胞（RBC）镰状化和脱水，导致毛细血管和小血管中的血管闭塞和血流受损。体外HbS聚合的生物化学是很好理解的。然而，在RBC内部，由于缺乏适当的测量方法和现实的模型，对由HbS聚合引起的细胞力学和粘附特性的潜在变化的机制知之甚少。三个研究团队在生物光子学（由麻省理工学院的Peter So领导），生物力学和微流体学（由麻省理工学院的Ming Dao领导）以及SCD治疗（由UPMC的Gregory Kato领导）方面具有互补的专业知识，将联手开发可以在RBC镰状化期间量化RBC生物力学的技术。虽然有许多因素导致血管闭塞，但已知RBC生物力学起着关键作用。预测性血管闭塞模型的发展将加深我们对SCD病因学的系统水平的理解，从而开发出更有效的药物和治疗方法。 为了实现这些目标，我们的团队将开发反射模式定量相位显微镜和三维耗散粒子动力学（DPD）多尺度模型。这些技术将使我们能够在具有精确控制的氧合水平的微流体设备内的镰状转变期间以前所未有的准确度量化RBC流变学特性。我们将进一步开发基于互补相位显微镜的光谱方法来量化HbS氧化和聚合状态。同时测量红细胞形状和流变学的变化与HbS生化状态的变化应使我们更好地了解细胞内分子水平的变化如何驱动红细胞生物力学，血管闭塞和SCD危机的关键因素。这种方法的功效将在初步研究中进行评估，以阐明羟基脲（FDA批准的唯一一种专门用于SCD的药物）和Aes-103（一种正在开发的新药）的治疗机制。这些研究将证明该平台可用于筛选新的抗镰状化药物。 UPMC镰状细胞病登记处将提供丰富的临床数据库，以注释将通过先进的RBC生物力学分析进行分析的患者标本。这将允许初步探索性统计相关性的临床特征的潜在生物标志物从生物力学测定。

DESCRIPTION (provided by applicant): Sickle cell disease (SCD), known in the homozygous form as sickle cell anemia, affects 1 in 50 African Americans with debilitating, chronic, crisis episodes and reduced life expectancy. SCD is an inherited blood disorder caused by a single point mutation in the beta-globin gene. Sickle hemoglobin (HbS) has the unique property of polymerizing when deoxygenated, triggering red blood cell (RBC) sickling and dehydration, leading to vaso-occlusion and impaired blood flow in capillaries and small vessels. The biochemistry of HbS polymerization in vitro is well understood. However, inside RBC, the mechanism of underlying changes in cell mechanics and adhesion properties resulting from HbS polymerization is poorly understood due to a lack of appropriate measurement methods and realistic models. Three research teams with complementary expertise in bio-photonics (lead by Peter So, MIT), in biomechanics and microfluidics (lead by Ming Dao, MIT), and in SCD treatment (lead by Gregory Kato, UPMC) will join force to develop technologies that can quantify RBC biomechanics during RBC sickling. While there are many factors contributing to vaso-occlusion, RBC biomechanics is known to play a key role. The development of a predictive vaso-occlusion model will deepen our understanding of SCD etiology on a system level allowing the development of more effective drugs and treatments. Toward these goals, our team will develop reflection mode quantitative phase microscopy and a 3-D dissipative particle dynamics (DPD) multi-scale model. These technologies together will allow us to quantify RBC rheological properties with unprecedented accuracy during sickling transition inside microfluidic devices with precisely controlled oxygenation level. We will further develop complementary phase microscopy based spectroscopic methods to quantify HbS oxygenation and polymerization states. Simultaneous measurement of changes in RBC shape and rheology with changes in HbS biochemical states should allow us to better understand how intracellular molecular level variations drive RBC biomechanics, a key factor in vaso-occlusion and SCD crisis. The power of this approach will be evaluated in pilot studies to elucidate the therapeutic mechanisms of hydroxyurea, the only FDA approved drug specifically for SCD, and Aes -103, a new drug under development. These studies will develop proof of principle that this platform could be utilized in screening new anti-sickling drugs. The UPMC sickle cell disease registry will provide a rich clinical database to annotate the patient specimens that will be analyzed by advanced RBC biomechanics assays. This will allow preliminary exploratory statistical correlation of clinical characteristics to the potential biomarkers derived from the biomechanics assays.