Characterization Of The Biophysical Impact Of Rigid Red Blood Cells In Sickle Cell Disease: Creating A Novel Path For Treatment

镰状细胞病（SCD）是一种遗传性血液病，影响约10万美国人和全球数百万人。SCD患者的寿命显著缩短，自童年起生活质量就受到损害，即，经常因急性疼痛危象、感染、急性呼吸问题和中风住院。 目前的治疗策略是有限的和高度侵入性的，例如，成瘾性麻醉剂（阿片类药物）和输血。 SCD最明显的指标是患者的红细胞（RBC）的变化，红细胞变得更加坚硬，通常从正常的圆形变形为新月形（“镰刀”）。 虽然这些变化是众所周知的，但关于仅由刚性红细胞产生的血流改变如何影响其他血细胞的功能，特别是白色血细胞（WBC）和血小板，这在感染和急性疼痛等疾病症状中起着重要作用，却知之甚少。 因此，该项目旨在开发一种独特的实验工具组合，以量化RBC刚性如何导致WBC和血小板相互作用的改变，从而导致与SCD相关的高感染率，凝血和疼痛危机。 获得的见解有望导致更好的治疗，旨在减少危机事件，感染，住院天数，最重要的是，对阿片类药物的需求。 该项目涉及生物学和工程学的多学科活动，为STEM领域创造了极好的教育和研究机会，展示了基础科学和工程学影响人类疾病治疗的巨大机会。研究结果将传播给广泛的受众，从K-12到本科和研究生水平，研究团队将在同意过程中向SCD患者和家庭提供教育，介绍镰状细胞研究的重要性，当地宣传以及患者如何参与他们的护理。尽管不可逆i-sRBC（不可逆i-sRBC）是SCD的标志，但在给定时间，这些细胞中只有一小部分存在于患者的血流中，这是由于它们的高溶解速率。 相反，高度刚性但非镰刀形细胞（可逆r-RBC）代表SCD中循环的主要镰刀形RBC。 然而，很少有人关注SCD中血流中r-sRBC的持续存在如何影响血液动力学和其他血细胞的功能，即，白色血细胞（WBC）和血小板，以及对微血管闭塞以外的疾病表现的下游贡献，这主要归因于i-sRBC，其在穿过身体时对重要器官（包括脾、肝和肺）造成显著的物理损伤。该项目的目标是开发和使用一种独特的实验工具组合来量化SCD中的r-sRBC刚性，并系统地探索这种刚性如何影响白色血细胞（WBC）和血小板的空间分布和动态行为，因为它与疾病症状有关，例如感染率和疼痛危象。该研究计划旨在测试SCD患者血液中的r-sRBC改变WBC和血小板的边缘化，影响其对SCD疾病症状的反应能力的中心假设。 研究计划有三个目标。 第一个目的是通过使用具有用于校准的人工硬化RBC的模型SCD血液的Ektacytometry来表征SCD患者血液中患病RBC群体的硬度。第二个目的是评价WBC和血小板粘附于血管壁如何随着SCD中不同水平的RBC硬度而变化，以及对疾病表现的下游影响。 第三个目标是使用流动粘附模型确定稀释刚性红细胞组分对WBC和血小板粘附能力的影响，就像输血过程中发生的那样。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Sickle cell disease (SCD) is a hereditary blood disease affecting approximately 100,000 Americans and millions more worldwide. Patients with SCD have a significantly shortened lifespan with a compromised quality of life since childhood, i.e., frequent hospitalization for acute pain crises, infections, acute breathing problems and strokes. Current treatment strategies are limited and highly invasive, e.g., addictive narcotics(opiods) and blood transfusions. The most visible indicators of SCD are changes in the patient's red blood cells (RBCs), which become more rigid and are often deformed from their normal round shape to a crescent ("sickle") shape. Though these changes are well known, little is known about how the blood flow alterations created solely by rigid RBCs impact the functionality of other blood cells, particularly white blood cells (WBCs) and platelets, which play an important role in disease symptoms such as infections and acute pain. Thus, this project seeks to develop a unique combination of experimental tools to quantify how RBC rigidity causes the altered WBC and platelet interactions that lead to the high rate of infection, blood clotting and pain crisis associated with SCD. Insights gained are expected to lead to better treatments aimed at reducing the number of crisis episodes, infection, hospital days, and most importantly, need for opioids. The project involves multi-disciplinary activities in biology and engineering that create excellent educational and research opportunities in STEM areas, showcasing the vast opportunities that exist for basic science and engineering to impact the treatment of human diseases. The research findings will be disseminated to a broad audience, from K-12 to undergraduate and graduate levels, and the research team will provide education to SCD patients and families during the consent process regarding the importance of research in sickle cell, local advocacy, and how patients can be involved in their care.Though rigid sickle shaped RBCs (irreversible i-sRBCs) are the hallmark of SCD, only a small fraction of these cells is present in the patient's bloodstream at a given time due to their high rate of lysing. Instead, the highly rigid, but not sickle-shaped cells (reversible r-RBCs) represent the main sickled RBCs circulating in SCD. However, little attention has been given to how the persistent presence of the r-sRBCs in the bloodstream in SCD may impact hemodynamics and the functionality of other blood cells, i.e., white blood cells (WBCs) and platelets, and the downstream contribution to disease manifestation beyond the occlusion of the microvasculature, which is primarily attributed to the i-sRBCs that cause significant physical damage to vital organs, including the spleen, liver, and lungs, when traveling through the body. The goal of this project is to develop and use a unique combination of experimental tools to quantify r-sRBC rigidity in SCD and to systematically explore how this rigidity affects the spatial distribution and the dynamic behavior of white blood cells (WBCs) and platelets as it relates to disease symptoms, such as infection rate and pain crisis. The research plan is designed to test the central hypothesis that the r-sRBCs in SCD patient blood alter the margination of WBC and platelets, impacting their ability to respond to disease symptoms in SCD. The Research Plan is organized under three objectives. The FIRST OBJECTIVE is to characterize the stiffness of the diseased RBC population in SCD patient blood via ektacytometry with a model SCD blood having artificially rigidified RBCs used for calibration. The SECOND OBJECTIVE is to evaluate how WBC and platelet adhesion to the blood vessel wall changes with varying level of RBC stiffness in SCD and the downstream impact on disease presentation. The THIRD OBJECTIVE is to determine the impact of diluting the stiff RBC fractions, as would occur during blood transfusion, on the ability of WBCs and platelets to adhere, using flow adhesion models.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.