Dissecting the origins of fetal hemoglobin modulation of sickle cell vaso-occlusion

剖析胎儿血红蛋白调节镰状细胞血管闭塞的起源

• 批准号: 9258476
• 负责人: David Kevin Wood
• 金额: $ 19.21万
• 依托单位: UNIVERSITY OF MINNESOTA
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-10 至 2019-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9258476
• 关键词: Affect; Animal Model; Biological Assay; Biological Markers; Blood; Blood specimen; Caring; Cells; Cessation of life; Clinical; Clinical Trials; Cytometry; Development; Erythrocytes; Fetal Hemoglobin; Fiber; Flow Cytometry; Goals; Health Care Costs; Hemoglobin A; Hemoglobin F Disease; Hereditary Disease; High Pressure Liquid Chromatography; Human; In Vitro; Individual; Infarction; Link; Measurement; Measures; Microfluidics; Monitor; Organ; Oxygen; Patient Monitoring; Patient-Focused Outcomes; Patients; Polymers; Probability; Quality of life; Risk; Role; Sampling; Sickle Cell; Sickle Cell Anemia; Sickle Hemoglobin; Testing; Therapeutic; Tissues; Treatment Efficacy; Variant; Work; blood rheology; clinical efficacy; hydroxyurea; improved; in vivo; individual patient; mutant; novel therapeutics; patient stratification; polymerization; public health relevance; response; tool

 DESCRIPTION: Sickle cell disease (SCD) is a devastating hereditary disorder that affects more than 13 million people worldwide with health care costs in the U.S. alone exceeding $1 billion per year. The origin of SCD is the ability of a hemo- globin mutant (sickle hemoglobin or HbS) to polymerize into rigid fibers upon deoxygenation. These fibers reduce red blood cell deformability, which leads to large changes in blood rheology and can ultimately result in complete occlusion of the microvasculature, tissue infarction, organ damage, and even death. The only clinically approved therapeutic for SCD, hydroxyurea, is thought to work by inducing synthesis of fetal hemoglobin (HbF). HbF is known to inhibit HbS polymerization in vitro, but average HbF levels in blood correlate only weakly with patient outcomes, and hydroxyurea has widely variable clinical efficacy. Although new therapies have been proposed or are in development, the effect of these potential therapies on vaso-occlusion is difficult to predict without extensive trials in animal models and humans. Ultimately, the missing link is to understand the quantitative rela- tionship between cellular HbF levels and the likelihood of vaso-occlusion. This would allow us to predict the potential efficacy of new therapies and to clinically monitor patients who are receiving HbF inducing therapies such as hydroxyurea. In these studies, we will quantify the relationship between blood HbF levels and the risk of vaso-occlusion. Our primary hypothesis is that the therapeutic efficacy of HbF depends primarily on the distribu- tion of HbF among red blood cells (RBCs). If all RBCs contain more than a threshold percentage of HbF, patients are protected from vaso-occlusion, but having the majority of HbF segregated into only a few cells does not significantly improve patient outcomes. We propose to directly test this hypothesis using flow cytometry to quan- tify single RBC HbF distributions ("HbF heterocellularity"). We will correlate the HbF heterocellularity of patient blood with the risk of vaso-occlusion. Because vaso-occlusions are difficult to study or reproduce in vivo, we have developed a microfluidic platform to study vaso-occlusion in vitro. We will use this platform to quantify the likelihood of occlusion in a blood sample, and we will correlate this measurement with HbF heterocellularity measured from patient samples using quantitative flow cytometry. The result will be a clinical assay that can be used to monitor patien response to hydroxyurea and an assay for clinical trials of new therapies that induce HbF synthesis. Additionally, we anticipate that these studies will elucidate whether HbF is the primary therapeutic mechanism for hydroxyurea.

 描述：镰状细胞疾病（SCD）是一种毁灭性的遗传性疾病，仅在美国，全世界的医疗费用就会影响超过1300万人，仅美国每年超过10亿美元。 SCD的起源是脱氧融合后血液全球突变体（镰状血红蛋白或HBS）聚合成刚性纤维的能力。这些纤维可减少红细胞的可变形性，从而导致血流变学的巨大变化，并最终导致微脉管系统，组织违规，器官损伤甚至死亡的完全阻塞。人们认为，唯一的SCD疗法是羟基脲，可以通过诱导胎儿血红蛋白（HBF）的合成来起作用。已知HBF在体外抑制HBS聚合，但血液中的平均HBF水平仅与患者的结局微弱相关，羟基脲的临床效率很大。尽管已经提出或正在开发新的疗法，但如果没有在动物模型和人类中进行广泛的试验，这些潜在疗法对血管咬合的影响很难预测。最终，缺失的链接是了解细胞HBF水平和血管批准的可能性之间的定量相对率。这将使我们能够预测新疗法的潜在有效性并在临床上 监测接受HBF诱导疗法（例如羟基脲）的患者。在这些研究中，我们将量化血液HBF水平与血管封闭的风险之间的关系。我们的主要假设是HBF的治疗效率主要取决于红细胞（RBC）中HBF的分布。如果所有RBC均包含超过HBF的阈值百分比，则可以保护患者免于血管cl缩，但是将大多数HBF隔离为仅少数细胞并不能显着改善患者预后。我们建议使用流式细胞仪直接检验该假设，以使单个RBC HBF分布（“ HBF杂细胞性”）。我们将将患者血液的HBF杂细胞与血管封闭的风险相关。由于血管凝集很难在体内研究或繁殖，因此我们开发了一个微流体平台来研究体外的血管clusion。我们将使用此平台来量化血液样本中闭塞的可能性，我们将使用定量流式细胞仪与患者样品测量的HBF杂细胞度相关联。结果将是一项临床评估，可用于监测患者对羟基脲的反应，以及用于诱导HBF合成的新疗法的临床试验的测定法。此外，我们预计这些研究将阐明HBF是否是羟基脲的主要治疗机制。