Long-term enzyme correction and lipid reduction in multiple organs of primary and secondary transplanted Fabry mice receiving transduced bone marrow cells

Fabry disease is a compelling target for gene therapy as a treatment strategy. A deficiency in the lysosomal hydrolase alpha-galactosidase A (alpha-gal A; EC ) leads to impaired catabolism of alpha-galactosyl-terminal lipids such as globotriaosylceramide (Gb3). Patients develop vascular occlusions that cause cardiovascular, cerebrovascular, and renal disease. Unlike for some lysosomal storage disorders, there is limited primary nervous system involvement in Fabry disease. The enzyme defect can be corrected by gene transfer. Overexpression of alpha-gal A by transduced cells results in secretion of this enzyme. Secreted enzyme is available for uptake by nontransduced cells presumably by receptor-mediated endocytosis. Correction of bystander cells may occur locally or systemically after circulation of the enzyme in the blood. In this paper we report studies on long-term genetic correction in an alpha-gal A-deficient mouse model of Fabry disease. alpha-gal A-deficient bone marrow mononuclear cells (BMMCs) were transduced with a retrovirus encoding alpha-gal A and transplanted into sublethally and lethally irradiated alpha-gal A-deficient mice. alpha-gal A activity and Gb3 levels were analyzed in plasma, peripheral blood mononuclear cells, BMMCs, liver, spleen, heart, lung, kidney, and brain. Primary recipient animals were followed for up to 26 weeks. BMMCs were then transplanted into secondary recipients. Increased alpha-gal A activity and decreased Gb3 storage were observed in all recipient groups in all organs and tissues except the brain. These effects occurred even with a low percentage of transduced cells. The findings indicate that genetic correction of bone marrow cells derived from patients with Fabry disease may have utility for phenotypic correction of patients with this disorder.     

Long-term correction of globotriaosylceramide storage in Fabry mice by recombinant adeno-associated virus-mediated gene transfer

Fabry disease is an X-linked recessive inborn metabolic disorder characterized by systemic and vascular accumulation of globotriaosylceramide (Gb(3)) caused by a deficiency of the lysosomal enzyme alpha-galactosidase A (alpha-gal A). The condition is associated with an increased morbidity and mortality due to renal failure, cardiac disease, and early onset of stroke. Hemizygous males are primarily affected clinically with variable expression in heterozygous females. Gene-therapy trials have been initiated recently in alpha-gal A knockout mouse models of Fabry disease by using a variety of viral vectors. In the present investigation we administered single i.v. injections of 1 x 10(10) genomes of recombinant adeno-associated virus (rAAV) encoding the human alpha-gal A gene driven by a modified chicken beta-actin (CAG) promoter to alpha-gal A knockout (Fabry) mice. Transgenic mice were analyzed for expression of alpha-gal A activity and Gb(3) levels in liver, kidney, heart, spleen, small intestine, lung, and brain. Administration of the rAAV-CAG-hAGA vector resulted in stable expression of alpha-gal A in organs of the Fabry mice for >6 months. alpha-Gal A activity in the organs became equal to or higher than that of wild-type mice. Accumulated Gb(3) in the liver, heart, and spleen was reduced to that of wild-type mice with lesser but significant reductions in kidney, lung, and small intestine. Injection of the rAAV-CAG-hAGA construct into skeletal muscle did not result in expression of alpha-gal A in it or in other tissues. This study provides a basis for a simple and efficient gene-therapy approach for patients with Fabry disease and is indicative of its potential for the treatment of other lysosomal storage disorders.     

Long-term systemic therapy of Fabry disease in a knockout mouse by adeno-associated virus-mediated muscle-directed gene transfer

Fabry disease is a systemic disease caused by genetic deficiency of a lysosomal enzyme, alpha-galactosidase A (alpha-gal A), and is thought to be an important target for enzyme replacement therapy. We studied the feasibility of gene-mediated enzyme replacement for Fabry disease. The adeno-associated virus (AAV) vector containing the alpha-gal A gene was injected into the right quadriceps muscles of Fabry knockout mice. A time course study showed that alpha-gal A activity in plasma was increased to approximately 25% of normal mice and that this elevated activity persisted for up to at least 30 weeks without development of anti-alpha-gal A antibodies. The alpha-gal A activity in various organs of treated Fabry mice remained 5-20% of those observed in normal mice. Accumulated globotriaosylceramide in these organs was completely cleared by 25 weeks after vector injection. Reduction of globotriaosylceramide levels was also confirmed by immunohistochemical and electronmicroscopic analyses. Echocardiographic examination of treated mice demonstrated structural improvement of cardiac hypertrophy 25 weeks after the treatment. AAV vector-mediated muscle-directed gene transfer provides an efficient and practical therapeutic approach for Fabry disease.     

Infusion of alpha-galactosidase A reduces tissue globotriaosylceramide storage in patients with Fabry disease

Fabry disease is a lysosomal storage disorder caused by a deficiency of the lysosomal enzyme alpha-galactosidase A (alpha-gal A). This enzymatic defect results in the accumulation of the glycosphingolipid globotriaosylceramide (Gb(3); also referred to as ceramidetrihexoside) throughout the body. To investigate the effects of purified alpha-gal A, 10 patients with Fabry disease received a single i.v. infusion of one of five escalating dose levels of the enzyme. The objectives of this study were: (i) to evaluate the safety of administered alpha-gal A, (ii) to assess the pharmacokinetics of i.v.-administered alpha-gal A in plasma and liver, and (iii) to determine the effect of this replacement enzyme on hepatic, urine sediment and plasma concentrations of Gb(3). alpha-Gal A infusions were well tolerated in all patients. Immunohistochemical staining of liver tissue approximately 2 days after enzyme infusion identified alpha-gal A in several cell types, including sinusoidal endothelial cells, Kupffer cells, and hepatocytes, suggesting diffuse uptake via the mannose 6-phosphate receptor. The tissue half-life in the liver was greater than 24 hr. After the single dose of alpha-gal A, nine of the 10 patients had significantly reduced Gb(3) levels both in the liver and shed renal tubular epithelial cells in the urine sediment. These data demonstrate that single infusions of alpha-gal A prepared from transfected human fibroblasts are both safe and biochemically active in patients with Fabry disease. The degree of substrate reduction seen in the study is potentially clinically significant in view of the fact that Gb(3) burden in Fabry patients increases gradually over decades. Taken together, these results suggest that enzyme replacement is likely to be an effective therapy for patients with this metabolic disorder.     

Enzymatic and functional correction along with long-term enzyme secretion from transduced bone marrow hematopoietic stem/progenitor and stromal cells derived from patients with Fabry disease.

Fabry disease is a lysosomal storage disorder that is due to a deficiency in alpha-galactosidase A (alpha-gal A). Previously we have shown that a recombinant retrovirus synthesized for the transfer of the human alpha-gal A coding sequence was able to engineer enzymatic correction of the hydrolase deficiency in fibroblasts and lymphoblasts from Fabry patients. The corrected cells secreted alpha-gal A that was taken up and utilized by uncorrected bystander cells, thus demonstrating metabolic cooperativity. In separate experiments we used transduced murine bone marrow cells and successfully tested and quantitated this phenomenon in vivo. In the present studies, which were designed to bring this therapeutic approach closer to clinical utility, we establish that cells originating from the bone marrow of numerous Fabry patients and normal volunteers can be effectively transduced and that these target cells demonstrate metabolic cooperativity. Both isolated CD34+-enriched cells and long-term bone marrow culture cells, including nonadherent hematopoietic cells and adherent stromal cells, were transduced. The transferred gene generates increased intracellular alpha-gal A enzyme activity in these cells. Further, it causes functional correction of lipid accumulation and provides for long-term alpha-gal A secretion. Collectively, these results indicate that a multifaceted gene transfer approach to bone marrow cells may be of therapeutic benefit for patients with Fabry disease.     

Fabry心肌病的诊断与治疗进展

法布里病（Fabry）是一种罕见的X染色体连锁遗传性疾病, 由于a-半乳糖苷酶A( alphagalactosidase A, GLA, 一种溶酶体酶)基因发生突变或缺失,引起体内GLA部分或全部缺乏,造成其代谢底物三己糖酰基鞘脂醇( globotriaosylceramide, Gb3)在人体各器官、组织蓄积,引起多个系统损害,其中心血管系统受累常见,主要表现为心肌肥厚、瓣膜损害、收缩/舒张功能减低,心律失常等,这些病变与患者心力衰竭、心源性猝死等密切相关。为了提高临床医生对Fabry病患者心脏受累表现的认识和诊治,本文将对Fabry 心肌病诊断与治疗的新进展作一综述。     

Aging accentuates and bone marrow transplantation ameliorates metabolic defects in Fabry disease mice

Fabry disease is an X-linked metabolic disorder caused by a deficiency of alpha-galactosidase A (alpha-Gal A). The enzyme defect leads to the systemic accumulation of glycosphingolipids with alpha-galactosyl moieties consisting predominantly of globotriaosylceramide (Gb3). In patients with this disorder, glycolipid deposition in endothelial cells leads to renal failure and cardiac and cerebrovascular disease. Recently, we generated alpha-Gal A gene knockout mouse lines and described the phenotype of 10-week-old mice. In the present study, we characterize the progression of the disease with aging and explore the effects of bone marrow transplantation (BMT) on the phenotype. Histopathological analysis of alpha-Gal A -/0 mice revealed subclinical lesions in the Kupffer cells in the liver and macrophages in the skin with no gross lesions in the endothelial cells. Gb3 accumulation and pathological lesions in the affected organs increased with age. Treatment with BMT from the wild-type mice resulted in the clearance of accumulated Gb3 in the liver, spleen, and heart with concomitant elevation of alpha-Gal A activity. These findings suggest that BMT may have a potential role in the management of patients with Fabry disease.     

Preselective gene therapy for Fabry disease

Fabry disease is a lipid storage disorder resulting from mutations in the gene encoding the enzyme alpha-galactosidase A (alpha-gal A; EC ). We previously have demonstrated long-term alpha-gal A enzyme correction and lipid reduction mediated by therapeutic ex vivo transduction and transplantation of hematopoietic cells in a mouse model of Fabry disease. We now report marked improvement in the efficiency of this gene-therapy approach. For this study we used a novel bicistronic retroviral vector that engineers expression of both the therapeutic alpha-gal A gene and the human IL-2Ralpha chain (huCD25) gene as a selectable marker. Coexpression of huCD25 allowed selective immunoenrichment (preselection) of a variety of transduced human and murine cells, resulting in enhanced intracellular and secreted alpha-gal A enzyme activities. Of particular significance for clinical applicability, mobilized CD34(+) peripheral blood hematopoietic stem/progenitor cells from Fabry patients have low-background huCD25 expression and could be enriched effectively after ex vivo transduction, resulting in increased alpha-gal A activity. We evaluated effects of preselection in the mouse model of Fabry disease. Preselection of transduced Fabry mouse bone marrow cells elevated the level of multilineage gene-corrected hematopoietic cells in the circulation of transplanted animals and improved in vivo enzymatic activity levels in plasma and organs for more than 6 months after both primary and secondary transplantation. These studies demonstrate the potential of using a huCD25-based preselection strategy to enhance the clinical utility of ex vivo hematopoietic stem/progenitor cell gene therapy of Fabry disease and other disorders.     

Narrative review: Fabry disease

Fabry disease is an X-linked, hereditary, lysosomal storage disease caused by deficiency of the enzyme alpha-galactosidase A, which results in the accumulation of the neutral glycosphingolipid globotriaosylceramide (Gb3) in the walls of small blood vessels, nerves, dorsal root ganglia, renal glomerular and tubular epithelial cells, and cardiomyocytes. It is a complex, multisystem disorder that is characterized clinically by chronic pain and acroparesthesia, gastrointestinal disturbances, characteristic skin lesions (angiokeratomata), progressive renal impairment, cardiomyopathy, and stroke. Enzyme replacement therapy (ERT) with intravenous infusions of recombinant human alpha-galactosidase A consistently decreases Gb3 levels in plasma and clears lysosomal inclusions from vascular endothelial cells. The effects of ERT on other tissues are not as obvious, suggesting that treatment must be initiated early in the course of the disease to be optimally effective or that some complications of the disease are not responsive to enzymes delivered intravenously.     

The heart in Anderson Fabry disease

Anderson Fabry disease is a life threatening, X-linked inborn metabolic defect of the lysosomal enzyme áalpha-galactosidase A. The deficiency of alpha-galactosidase A leads to a progressive accumulation of globotriaosylceramide (Gb(3)), the major glycosphingolipid substrate of the enzyme, within vulnerable cells, tissues, and organs, including the cardiovascular system. Cardiac involvement is frequent and patients with cardiac affection develop progressive hypertrophic infiltrative cardiomyopathy, valvular abnormalities, arrhythmias, and conduction abnormalities and may develop coronary heart disease. Hemizygous male patients have no detectable alpha-galactosidase A activity, while affected heterozygous females may have normal level of alpha-galactosidase A activity. Death occurs in male patients at 45 to 50 years, about 15 to 20 years earlier than in female patients due to a vicious circle from chronic renal insufficiency, arterial hypertension, atherosclerotic lesions and cerebrovascular hemorrhage or insults, and cardiomyopathy. Cardiac involvement in hetero- and hemizygotes will be discussed as well as the influence of enzyme replacement of alpha-galactosidase A.     

A novel 6 bp insertion in exon 7 associated with an unusual phenotype in a family with Fabry disease

A male patient presented with oligosymptomatic Fabry disease (end stage renal failure and non-obstructive cardiomyopathy) at around 30 years of age. His leukocyte alpha-galactosidase activity (alpha-gal) was 2.6% of controls. A 50-year-old sister had similar cardiac symptoms and her asymptomatic heterozygous daughter (33 years) had normal enzyme activity. All three patients carried a novel, 6bp insertion on exon 7 of the AGAL gene. The majority of male Fabry patients carrying mutations in exon 7 have residual alpha-gal below 1% and suffer from neuropathic pain. Comparable oligosymptomatic phenotypes in Caucasian patients carry a common mutation on exon 6 (R301Q) and have a significantly later onset. The course of the disease is likely to be altered by recombinant enzyme therapy in the future. Therefore, a thorough documentation of phenotypes, residual activities and underlying genotypes is of current interest.     

The 30-year Natural History of Non-classic Fabry Disease with an R112H Mutation

Fabry disease is a rare X-linked lysosomal storage disorder caused by mutations in the alpha-galactosidase A (GLA) gene that results in deficiency of the enzyme GLA and leads to the accumulation of globotriaosylceramide (GL-3) in cells. The accumulation of GL-3 may lead to life-threatening complications. Significant advances in genetic sequencing technology have led to a better understanding of genotype-phenotype interactions in Fabry disease. Fabry disease with an R112H mutation is known as the non-classic type. However, the long-term clinical course of the disease remains unknown. We herein report a patient with a 30-year natural history of non-classic Fabry disease with an R112H mutation.     

Genomic abnormalities of the murine model of Fabry disease after disease-related perturbation, a systems biology approach

Fabry disease is a disorder of alpha-D-galactosyl-containing glycolipids resulting from a deficiency of alpha-galactosidase A. Patients have a poorly understood vascular dysregulation. We hypothesized that disease-related perturbation by using enzyme replacement therapy in the murine model of Fabry disease would provide insight into abnormal biological processes in Fabry disease. Gene expression analyses of the heart, aorta, and liver of male alpha-galactosidase A knockout mice 28 weeks of age were compared with that of WT mice. Microarray analyses were performed before and after six weekly injections of alpha-galactosidase A. Alteration of Rpgrip1 ranked highest statistically in all three organs when knockout mice were compared with WT, and its splice variants responded in a unique way to alpha-galactosidase A. Enzyme replacement therapy tended to not only normalize gene expression, e.g., reduce the overexpression of securin, but also specifically modified gene expression in each tissue examined. Following multiple comparison analysis, gene expression correlation graphs were constructed, and a priori hypotheses were examined by using structural equation modeling. This systems biology approach demonstrated multiple and complex parallel cellular abnormalities in Fabry disease. These abnormalities form the basis for informed, in a Bayesian sense, sequential, hypothesis-driven research that can be subsequently tested experimentally.     

Bioluminescent imaging of a marking transgene and correction of Fabry mice by neonatal injection of recombinant lentiviral vectors

Successful therapy for many inherited disorders could be improved if the intervention were initiated early. This is especially true for lysosomal storage disorders. Earlier intervention may allow metabolic correction to occur before lipid buildup has irreversible consequences and/or before the immune system mounts limiting responses. We have been developing gene therapy to treat lysosomal storage disorders, especially Fabry disease. We describe studies directed toward metabolic correction in neonatal animals mediated by recombinant lentiviral vectors. To develop this method, we first injected a marking lentiviral vector that engineers expression of luciferase into the temporal vein of recipient neonatal animals. The use of a cooled charged-coupled device camera allowed us to track transgene expression over time in live animals. We observed intense luciferase expression in many tissues, including the brain, that did not diminish over 24 weeks. Next, we injected neonatal Fabry mice a single time with a therapeutic lentiviral vector engineered to express human alpha-galactosidase A. The injection procedure was well tolerated. We observed increased plasma levels of alpha-galactosidase A activity starting at our first plasma collection point (4 weeks). Levels of alpha-galactosidase A activity were found to be significantly elevated in many tissues even after 28 weeks. No immune response was observed against the corrective transgene product. Increased levels of enzyme activity also led to significant reduction of globotriaosylceramide in the liver, spleen, and heart. This approach provides a method to treat lysosomal storage disorders and other disorders before destructive manifestations occur.     

Correction in trans for Fabry disease: expression, secretion and uptake of alpha-galactosidase A in patient-derived cells driven by a high-titer recombinant retroviral vector.

Fabry disease is an X-linked metabolic disorder due to a deficiency of alpha-galactosidase A (alpha-gal A; EC 3.2.1.22). Patients accumulate glycosphingolipids with terminal alpha-galactosyl residues that come from intracellular synthesis, circulating metabolites, or from the biodegradation Of senescent cells. Patients eventually succumb to renal, cardio-, or cerebrovascular disease. No specific therapy exists. One possible approach to ameliorating this disorder is to target corrective gene transfer therapy to circulating hematopoietic cells. Toward this end, an amphotropic virus-producer cell line has been developed that produces a high titer (>10(6) i.p. per ml) recombinant retrovirus constructed to transduce and correct target cells. Virus-producer cells also demonstrate expression of large amounts of both intracellular and secreted alpha-gal A. To examine the utility of this therapeutic vector, skin fibroblasts from Fabry patients were corrected for the metabolic defect by infection with this recombinant virus and secreted enzyme was observed. Furthermore, the secreted enzyme was found to be taken up by uncorrected cells in a mannose-6-phosphate receptor-dependent manner. In related experiments, immortalized B cell lines from Fabry patients, created as a hematologic delivery test system, were transduced. As with the fibroblasts, transduced patient B cell lines demonstrated both endogenous enzyme correction and a small amount of secretion together with uptake by uncorrected cells. These studies demonstrate that endogenous metabolic correction in transduced cells, combined with secretion, may provide a continuous source of corrective material in trans to unmodified patient bystander cells (metabolic cooperativity).     

Correction of cardiac abnormalities in fabry mice by direct intraventricular injection of a recombinant lentiviral vector that engineers expression of alpha-galactosidase A.

BACKGROUND: Recombinant lentiviral vectors (LVs) offer the possibility of stable, long-term expression of transgenes even in non-dividing cells. In the present study this vector system was applied to a clinically relevant cardiovascular problem. METHODS AND RESULTS: Fabry disease results from deficient activity of alpha-galactosidase A (alpha-gal A) and cardiac abnormalities are a common and an important cause of death in patients with the disease. A therapeutic LV that delivers the alpha-gal A cDNA has been synthesized. In vitro studies established efficient transduction of the H9c2 rat cardiomyocytes and showed overexpression of enGFP (control) and alpha-gal A. In in vivo studies, the enGFP cDNA was transferred into C57BL/6 mouse hearts by direct intraventricular injection. Next, in a mouse model of Fabry disease, the recombinant therapeutic construct was delivered analogously. In cardiac tissue, alpha-gal A activity rose to 23% of normal levels at day 7 after LV injection, which is encouraging because levels of correction approximating 5% of normal may be curative for this disorder. There was also a corresponding reduction in globotriaosylceramide accumulation. Other organs assayed showed no detectable changes in alpha-gal A activity levels in injected animals. CONCLUSION: A localized benefit of directly injecting a therapeutic LV into the heart has been shown, confirming the utility of this delivery system for research and therapy for a variety of cardiovascular disorders.     

Cardiac Involvement in Fabry Disease: JACC Review Topic of the Week

Fabry disease (FD) is a rare X-linked inherited lysosomal storage disorder caused by deficient α-galactosidase A activity that leads to an accumulation of globotriasylceramide (Gb3) in affected tissues, including the heart. Cardiovascular involvement usually manifests as left ventricular hypertrophy, myocardial fibrosis, heart failure, and arrhythmias, which limit quality of life and represent the most common causes of death. Following the introduction of enzyme replacement therapy, early diagnosis and treatment have become essential to slow disease progression and prevent major cardiac complications. Recent advances in the understanding of FD pathophysiology suggest that in addition to Gb3 accumulation, other mechanisms contribute to the development of Fabry cardiomyopathy. Progress in imaging techniques have improved diagnosis and staging of FD-related cardiac disease, suggesting a central role for myocardial inflammation and setting the stage for further research. In addition, with the recent approval of oral chaperone therapy and new treatment developments, the FD-specific treatment landscape is rapidly evolving.     

Maladie de Fabry : quand y penser ?

Fabry disease is the second most frequent lysosomal storage disorder. It is a X-linked genetic disease secondary to alpha-galactosidase A enzyme deficiency. This is a progressive and systemic disease that affects both males and females. Classical symptoms and organ involvements are acral pain crisis, cornea verticillata, hypertrophic cardiomyopathy, stroke and chronic kidney disease with proteinuria. Nevertheless, organ damages can be missing or pauci-symptomatic and other common symptoms are poorly recognised, such as gastrointestinal or ear involvement. In classical Fabry disease, symptoms first appear during childhood or teenage in males, but later in females. Patients may have non-classical or late-onset Fabry disease with delayed manifestations or with single-organ involvement. Recognition of Fabry disease is important because treatments are available, but it may be challenging. Diagnosis is easy in males, with dosage of alpha-galactosidase A enzyme activity into leukocytes, but more difficult in females who can express normal residual activity. Other plasmatic biomarkers, such as lyso-globotriaosylceramide (lyso-Gb3), are interesting in females, but need to be associated with GLA gene analysis. In this review, we aimed at summarize the main clinical manifestations of Fabry disease and propose a practical algorithm to know how to diagnose this complex disease.     

Enzyme replacement therapy in heterozygous females with Fabry disease: Results of a phase IIIB study

Fabry disease is an X-linked glycosphingolipid storage disorder caused by a deficiency of alpha-galactosidase A. Affected patients experience debilitating neuropathic pain and have premature mortality due to renal failure, cardiovascular disease or cerebrovascular complications. The disease may be X-linked dominant, since most females heterozygous for Fabry disease are affected clinically. We evaluated the safety, efficacy and pharmacokinetics of agalsidase alfa (Replagal) administered intravenously to female patients with Fabry disease in an open-label, single-centre study. Fifteen severely affected patients received agalsidase alfa at 0.2 mg/kg every other week for up to 55 weeks. Agalsidase alfa was safe and well-tolerated in female patients. None of the patients developed antibodies or experienced an infusion reaction to agalsidase alfa. The pharmacokinetic profile of agalsidase alfa in female patients is comparable to the pharmacokinetics of agalsidase alfa in male patients. Mean urine sediment and plasma Gb3 levels decreased from baseline at 13, 27 and 41 weeks. A significant decrease in left ventricular mass from baseline was seen at weeks 27 (p = 0.003) and 41 (p = 0.039), and a significant reduction in QRS durations was seen at week 27 (p = 0.007). Furthermore, there was a significant improvement in quality of life. Renal function did not deteriorate in these 15 female patients over the 13- to 41-week period of observation. We conclude that enzyme replacement therapy with agalsidase alfa was safe and effective in female patients heterozygous for Fabry disease.     

Effective cell and gene therapy in a murine model of Gaucher disease

Gaucher disease (GD) is a lysosomal storage disorder due to an inherited deficiency in the enzyme glucosylceramidase (GCase) that causes hepatosplenomegaly, cytopenias, and bone disease as key clinical symptoms. Previous mouse models with GCase deficiency have been lethal in the perinatal period or viable without displaying the clinical features of GD. We have generated viable mice with characteristic clinical symptoms of type 1 GD by conditionally deleting GCase exons 9-11 upon postnatal induction. Both transplantation of WT bone marrow (BM) and gene therapy through retroviral transduction of BM from GD mice prevented development of disease and corrected an already established GD phenotype. The gene therapy approach generated considerably higher GCase activity than transplantation of WT BM. Strikingly, both therapeutic modalities normalized glucosylceramide levels and practically no infiltration of Gaucher cells could be observed in BM, spleen, and liver, demonstrating correction at 5-6 months after treatment. The findings demonstrate the feasibility of gene therapy for type 1 GD in vivo. Our type 1 GD mice will serve as an excellent tool in the continued efforts toward development of safe and efficient cell and gene therapy for type 1 GD.