Saenko Evgueni L, Ananyeva Natalya M, Moayeri Morvarid, Ramezani Ali, Hawley Robert G
Department of Biochemistry, Holland Laboratory, American Red Cross, 15601 Crabbs Branch Way, Rockville, MD 20855, USA.
Curr Gene Ther. 2003 Feb;3(1):27-41. doi: 10.2174/1566523033347417.
Hemophilia A, the most common inherited bleeding disorder, is caused by deficiency or functional defects in coagulation factor VIII (fVIII). Conventional treatment for this disease involves intravenous infusions of plasma-derived or recombinant fVIII products. Although replacement therapy effectively stops the bleeding episodes, it has a risk of transmission of viral blood-borne diseases and development of neutralizing antibodies that inactivate the administered fVIII protein. Hemophilia A is an attractive candidate for application of gene therapy approaches because the therapeutic window is wide and even modest elevation of fVIII levels will correct the hemophilic phenotype. Ongoing preclinical investigations utilize animal models of hemophilia A, including genetically fVIII-deficient mice and naturally fVIII-deficient dogs, to optimize vectors, transgenes and target cell populations for Phase I clinical trials. In this review, we outline the progress in understanding the mechanisms of fVIII turnover, which provides a basis for development of improved fVIII molecules with prolonged half-life in the circulation. We discuss the possibility of incorporating these improved fVIII molecules as transgenes into self-inactivating lentiviral vectors carrying chromatin insulator sequences, representing a new generation of gene delivery vehicle, to target hematopoietic stem cells and endothelial cells. The use of hematopoietic stem cells as the target cell population may prevent inhibitor formation to transduced fVIII by induction of immune tolerance. Alternatively, endothelial cells may support optimal synthesis of fVIII and myeloablative conditioning of patients with radiation or chemotherapy may not be required for efficient engraftment of the engineered cells. Collectively, these proposed advances represent promising prophylactic strategies toward long-term correction of the coagulation defect in this progressively debilitating, life-threatening disease.
甲型血友病是最常见的遗传性出血性疾病，由凝血因子VIII（fVIII）缺乏或功能缺陷引起。该疾病的传统治疗方法包括静脉输注血浆源性或重组fVIII产品。尽管替代疗法能有效止血，但存在传播病毒性血源性疾病以及产生使所输注的fVIII蛋白失活的中和抗体的风险。甲型血友病是基因治疗方法应用的一个有吸引力的候选对象，因为其治疗窗口较宽，即使fVIII水平适度升高也能纠正血友病表型。正在进行的临床前研究利用甲型血友病动物模型，包括基因敲除fVIII的小鼠和天然缺乏fVIII的犬，来优化用于I期临床试验的载体、转基因和靶细胞群体。在这篇综述中，我们概述了在理解fVIII周转机制方面取得的进展，这为开发在循环中半衰期延长的改良fVIII分子提供了基础。我们讨论了将这些改良的fVIII分子作为转基因整合到携带染色质绝缘子序列的自失活慢病毒载体中的可能性，这种载体代表了新一代的基因递送工具，可靶向造血干细胞和内皮细胞。使用造血干细胞作为靶细胞群体可能通过诱导免疫耐受来防止对转导的fVIII形成抑制剂。另外，内皮细胞可能支持fVIII的最佳合成，并且对于工程细胞的有效植入可能不需要对患者进行放疗或化疗的清髓预处理。总体而言，这些提出的进展代表了针对这种逐渐使人衰弱、危及生命的疾病中凝血缺陷进行长期纠正的有前景的预防策略。
