PRENATAL STRATEGIES FOR TREATMENT OF HEMOGLOBINOPATHIES

使用无毒的骨髓修复方案在血红蛋白病患者中建立稳定的混合造血嵌合体的成功临床策略可以治愈大量骨髓移植毒性被禁止的患者。子宫内造血干细胞移植(IUHSCTx)是一种有希望的非清髓性方法，可以持续地实现混合异基因嵌合体。IUHSCTx临床应用于血红蛋白疾病的策略包括：1)IUHSCTx重建以获得足够水平的供者异基因嵌合体以达到治疗效果；2)产前诱导特异性耐受，随后使用最小的清髓方案加强出生后的植入。这项建议的总体目标是研究治疗血红蛋白疾病的产前策略。该建议的具体目的是：1)利用转基因的血红蛋白病小鼠模型，比较IUHSCTx在不同类型和严重程度的血红蛋白病的生物环境中建立混合同种异体嵌合体的潜力。IUHSCTx的疗效将在不同类型和严重程度的转基因小鼠模型中进行评估；2)对比和比较子宫内移植后包含HSC群体和专业抗原提呈细胞(APC)促进缺失耐受的能力。将评估供者来源的APC群体迁移到受者胸腺的能力，目前的供者特异性抗原，以及介导适当的同种异体反应性T细胞的克隆性删除的能力；以及3)测试在产前建立混合异基因嵌合体和/或供者特异性耐受后，在有或没有最低限度骨髓修复方案的情况下，出生后再次移植策略增加出生后植入的有效性。同样的供者出生后移植到增强植入的效果将在已定义的模型系统中进行评估，这些模型系统允许分析：a)实现中枢缺失耐受的重要性；b)最小骨髓修复方案的影响；c)血红蛋白病的存在；以及对该方法成功的影响。

Successful clinical strategies to establish stable mixed hematopoietic chimerism in patients with hemoglobinopathies using non-toxic myelopreparative regimens could cure a large number of patients for whom the toxicity of bone marrow transplantation is prohibitive. A promising non-myeloablative approach that can consistently achieve mixed allochimerism is in utero hematopoietic stem cell transplantation (IUHSCTx). Strategies for the clinical application of IUHSCTx to the hemoglobinopathies include: 1) reconstitution by IUHSCTx to achieve adequate levels of donor allochimerism for therapeutic effect; and 2) prenatal specific tolerance induction with subsequent postnatal enhancement of engraftment using minimal myeloablative regimens. The overall goal of this proposal is to investigate prenatal strategies for the treatment of the hemoglobinopathies. The specific aims of the proposal are: 1) To compare the potential of IUHSCTx to establish mixed allochimerism in the biologic milieu of different types and severity of hemoglobinopathy, using transgenic murine models of hemoglobinopathy. The efficacy of IUHSCTx will be assessed in transgenic murine models of different types and severity of hemoglobinopathy; 2) To contrast and compare the ability of HSC containing populations versus professional antigen presenting cells (APCs) to facilitate deletional tolerance after in utero transplantation. Populations of donor-derived APCs will be assessed for their ability to migrate to the recipient thymus, present donor specific antigen, and mediate clonal deletion of appropriate alloreactive T-cells; and 3) To test the efficacy of postnatal re-transplantation strategies with or without minimal myelopreparative regimens to augment engraftment after birth following the prenatal establishment of mixed allochimerism and/or donor specific tolerance. The efficacy of same donor transplants after birth to augment engraftment will be assessed in defined model systems that allow analysis of: a) the importance of achieving central deletional tolerance; b) the impact of minimal myelopreparative regimens; and c) the presence of hemoglobinopathy; on the success of this approach.