In Utero Stem Cell Transplantation for Hemophilia A

描述(由申请人提供)： 血友病A是一种由凝血因子VIII缺乏/异常引起的X连锁隐性出血性疾病。目前，血友病的治疗方法包括使用新鲜冰冻血浆、冷沉淀或凝血因子VIII浓缩物进行因子置换。虽然这极大地改善了血友病患者的生活质量，但这并不理想，因为患者的一生都需要定期治疗。在子宫内治疗血友病将使疾病发生前得到纠正，从而使不需要进一步治疗的健康婴儿出生。我们的实验室开发和优化了一种独特的羊子宫内干细胞移植(IUSCT)模型，该模型允许在没有预适应的情况下，通过早期妊娠受体的前免疫状态来植入和分化人类干细胞。该模型已被证明是评估IUSCT方法的准确和有价值的临床前系统，该模型中产生的数据被用于在X-SCID患者中进行第一次成功的临床IUSCT。除了持久的造血植入，移植的造血干细胞(HSC)和骨髓间充质干细胞(MSC)也在这个模型中产生了其他组织，包括大量的功能性肝细胞。这些结果表明，成人骨髓来源的干细胞可能非常适合用于细胞治疗，以纠正血友病等疾病，在血友病中，肝脏来源的因子存在缺陷或缺失。在目前的方案中，我们将通过利用冷冻精液重建一种症状与人类血友病A非常相似的自发性凝血因子VIII缺乏的绵羊品系来检验这一假设，同时将正常绵羊胚胎与成年造血干细胞和骨髓间充质干细胞一起移植，以确定在体内产生功能性肝细胞的最佳干细胞群(S)。然后，我们将在最佳干细胞群(S)下将受影响的胎儿移植到子宫内，并评估这种宫内细胞治疗方法是否在这个具有临床意义的血友病A大型动物模型中产生治疗效益。我们还将检查受体血友病绵羊的肝脏和其他组织，以建立临床改善程度与移植的成人HSC和MSC产生的第八因子细胞水平之间的相关性。希望这些使用成人骨髓来源的干细胞的研究将导致开发一种成功的基于干细胞的治疗方法来治疗出生前的血友病，从而消除终身因子治疗的需要，因为其固有的风险/缺点。

DESCRIPTION (provided by applicant): Hemophilia A is an X-linked recessive bleeding disorder caused by the deficiency/abnormality of Factor VIII. Currently, treatment of hemophilia involves factor replacement using fresh frozen plasma, cryoprecipitate, or Factor VIII concentrate. While this greatly improves the quality of life of hemophiliacs, it is less than ideal, since regular treatments are required throughout the life of the patient. Treating hemophilia in utero would enable correction prior to disease onset, thus allowing the birth of a healthy baby who requires no further treatment. Our laboratory has developed and optimized a unique sheep model for in utero stem cell transplantation (IUSCT) that allows the engraftment and differentiation of human stem cells in the absence of preconditioning, by virtue of the early gestational recipient's pre-immune status. This model has proven to be an accurate and valuable pre-clinical system for evaluating approaches to IUSCT, and the data generated in this model was used to conduct the first successful clinical IUSCT in a patient with X-SCID. In addition to the durable hematopoietic engraftment, transplanted hematopoietic stem cells (HSC) and marrow-derived mesenchymal stem cells (MSC) also give rise to other tissues in this model, including significant numbers of functional hepatocytes. These results suggest that adult marrow-derived stem cells may be ideally suited for cellular therapy to correct disorders such as the hemophilias in which a liver-derived factor is defective or absent. In the present proposal we will test this hypothesis by utilizing cryopreserved semen to re-establish a line of sheep that exhibited spontaneous factor VIII deficiency with symptomology closely mimicking that of human hemophilia A, while simultaneously transplanting normal sheep fetuses with adult HSC and MSC to determine the optimal stem cell population(s) for generating functional hepatic cells in vivo. We will then transplant the affected fetuses in utero with the optimal stem cell population(s) and assess whether this in utero cell therapy approach produces therapeutic benefit in this clinically relevant large animal model of hemophilia A. We will also examine the liver and other tissues of the recipient hemophilic sheep to establish a correlation between the degree of clinical improvement and the levels of Factor VIII-producing cells generated by the transplanted adult human HSC and MSC. It is hoped that these studies using adult BM-derived stem cells will lead to the development of a successful stem cell-based therapeutic approach to treat hemophilia prior to birth, thus obviating the need for lifelong factor therapy with its inherent risks/shortcomings.