ENZYME AND GENE THERAPY OF MPS I IN ANIMAL MODELS

粘多糖沉积症I（MPS I、Hurler、Hurler/Scheie和Scheie综合征）的分子基础是编码α-L-艾杜糖醛酸酶的基因突变，导致酶活性缺失、未降解糖胺聚糖蓄积和全身性疾病。 由于α-L-艾杜糖醛酸酶（一种溶酶体酶）可以分泌并通过受体介导的内吞作用摄取，因此MPS I长期以来一直被认为是替代治疗的主要候选药物。 造血来源的供体细胞（可能是巨噬细胞）提供的α-L-艾杜糖醛酸酶被认为是骨髓移植后观察到的疾病进展变化的原因。 也可通过给予重组α-L-艾杜糖醛酸酶改变病程。 先前在犬MPS I模型中观察到的酶的治疗效果已经足够有希望在MPS I患者中进行临床试验。 但是，即使重组α-L-艾杜糖醛酸酶可能很快成为一种药物，仍然需要开发有效和持久的基因治疗。 为了获得合适的动物模型，我们通过靶向破坏α-L-艾杜糖醛酸酶基因产生了突变小鼠。 目的1是在生化、病理、行为和临床水平上确定MPS I小鼠模型的表型。 目的2是确定给予人重组α-L-艾杜糖醛酸酶对疾病表型的影响，以便为基于基因的程序提供比较基础。 目的3是比较过表达人α-L-艾杜糖醛酸酶的基因修饰骨髓移植与表达正常水平酶的骨髓移植在改变疾病表型方面的有效性。 目的4是确定巨噬细胞中四环素诱导的α-L-艾杜糖醛酸酶表达作为酶递送至受影响器官（特别是脑）的手段的有效性，以及将其与上述程序改变疾病表型的能力进行比较。 拟定的研究代表了我们为MPS I患者开发治疗的长期项目中的步骤。

The molecular basis of Mucopolysaccharidosis I (MPS I, Hurler, Hurler/Scheie and Scheie syndromes) is mutations in the gene encoding alpha-L-iduronidase, resulting in absence of enzyme activity, accumulation of undegraded glycosaminoglycans, and systemic disease. Because alpha-L-iduronidase, a lysosomal enzyme, can be secreted as well as taken up by receptor-mediated endocytosis, MPS I has long been considered a prime candidate for replacement therapy. Alpha-L-Iduronidase provided by donor cells of hematopoietic origin (probably macrophages) is thought to be responsible for changes in disease progression that are seen after bone marrow transplantation. The course of the disease can also be altered by administration of recombinant alpha-L-iduronidase. The therapeutic effect of the enzyme previously observed in the canine MPS I model had been promising enough to generate a clinical trial in MPS I patients. But even though recombinant alpha-L-iduronidase may soon become available as a pharmaceutical, there is still a need for developing effective and long-lasting gene therapy. To have a suitable animal model, we have produced mutant mice by targeted disruption of the alpha-L-iduronidase gene. Aim 1 is to define the phenotype of the MPS I mouse model at the biochemical, pathological, behavioral and clinical levels. Aim 2 is to determine the effect of administration of human recombinant alpha-L-iduronidase on the disease phenotype, in order to provide a basis of comparison for gene-based procedures. Aim 3 is to compare transplantation of gene-modified bone marrow over-expressing human alpha-L-iduronidase with transplantation of bone marrow expressing normal levels of the enzyme, for effectiveness in altering the disease phenotype. Aim 4 is to determine the effectiveness of tetracycline-inducible alpha-L-iduronidase expression in macrophages as a means of enzyme delivery to affected organs, in particular to the brain, as well as to compare it with the above procedures for ability to alter the disease phenotype. The proposed studies represent steps in our long-term program to develop treatment for patients affected with MPS I.