Development of Novel Cell Therapies for Gaucher Disease

Group members: Maria Dahl, Ida Berglin-Enquist, Eva Nilsson, Johan Richter and Stefan Karlsson

Goals:

1. Develop and characterize mouse models for different subtypes of Gaucher disease
2. Develop safe and effective gene therapy using both patient cells and mouse models.

Background

Gaucher disease (GD)

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by a deficiency in the enzyme glucocerebrosidase (GCase) (1) . The disease is characterized by accumulation of glucocerebroside in macrophages and macrophage-derived cells in various tissues. Gaucher disease is divided into 3 subtypes based on the absence (type 1) or presence and severity (types 2 and 3) of central nervous system (CNS) symptoms. The current treatment for GD is enzyme replacement therapy (ERT) which works very well for the treatment of visceral symptoms in most GD patients (2,3) . However, this lifelong parenteral treatment is not a permanent cure for the disease. In addition since the administered enzyme cannot cross the blood brain barrier it is not effective in treating the CNS associated symptoms of type 2 and 3 GD patients. Because macrophages are derived from bone marrow stem cells, allogeneic bone marrow transplantation (BMT) has been applied successfully in a small number of GD patients. BMT can be associated with severe morbidity and mortality, and only a small fraction of patients have appropriate histocompatible donors. Therefore, several investigators have attempted to develop gene therapy for GD by gene transfer of the glucocerebrosidase (GCase) gene into hematopoietic stem cells (4) . However, lack of a suitable animal model has been the main obstacle in developing gene therapy for GD. Animal models for the neuronopathic form of GD would in addition not only provide tools for the evaluation of novel therapies but also be useful to elucidate the mechanisms behind the CNS pathology.

Project description

Gene therapy

We have generated a viable mouse model for type 1 GD using the Cre/loxP system which enables induction of enzyme deficiency after birth (5) . This animal model, in contrast to previous viable models (6) exhibits prominent pathological features of type 1 Gaucher disease, including splenomegaly that increase over time. Using this model we have shown that it is possible to correct the disease phenotype by bone marrow transplantation and gammaretroviral gene therapy of hematopoietic stem cells. We are now characterizing the hematopoietic defect in these animals and asking whether gene therapy causes selection of gene-corrected cells at different levels of the hematopoietic hierarchy. We are developing safer gammaretroviral and lentiviral vectors to minimize genotoxicity by insertional mutagenesis in the context of gene therapy. Similarly, we are developing gene therapy protocols that minimize the risks of transplantation by using non-myeloablative conditioning regimens that may be useful in future clinical gene therapy trials for type 1 GD.This project is in progress but recent findings from our laboratory indicate that relatively few stem cells need to be corrected to result in a therapeutic benefit (7).

Models for neuronopathic GD

We have also generated neuronopathic mouse models for Gaucher disease will be used to elucidate the mechanisms behind the CNS pathology in type 2 Gaucher disease as well as development of new therapies to treat the CNS symptoms (8).

Figure 1: Representative images showing how gene therapy can correct the Gaucher disease phenotype in our GD mice. Disease characteristic “Gaucher cells” are practically eliminated in the spleen 5 months after transplantation of bone marrow cells that have been transduced with a retroviral vector containing the GC gene (hematoxylin-eosin and PAS staining, scale bars are 50 µm).

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References:

1. Beutler, E., Grabowski, G.A. (2001). Gaucher Disease. The Metabolic & Molecular Bases of Inherited Disease . C. R. Scriver, Beaudet, A.L., Sly, W.S., Valle, D. New York, McGraw-Hill. 3: 3635-3668.
2. Barton, N. W., F. S. Furbish, et al. (1990). "Therapeutic response to intravenous infusions of glucocerebrosidase in a patient with Gaucher disease." Proc Natl Acad Sci U S A 87 (5): 1913-6.
3. Beutler, E. (2004). "Enzyme replacement in Gaucher disease." PLoS Med 1 (2): e21.
4. Dunbar, C. E., D. B. Kohn, et al. (1998). "Retroviral transfer of the glucocerebrosidase gene into CD34+ cells from patients with Gaucher disease: in vivo detection of transduced cells without myeloablation." Hum Gene Ther 9 (17): 2629-40.
5. Enquist, I. B., E. Nilsson, et al. (2006). "Effective cell and gene therapy in a murine model of Gaucher disease." Proc Natl Acad Sci U S A 103 (37): 13819-24.
6. Xu, Y. H., B. Quinn, et al. (2003). "Viable mouse models of acid beta-glucosidase deficiency: the defect in Gaucher disease." Am J Pathol 163 (5): 2093-101
7. Enquist IB, Nilsson E, Månsson JE, Ehinger M, Richter J, Karlsson S (2009) "Successful low-risk hematopoietic cell therapy in a mouse model of type 1 Gaucher disease." Stem Cells Mar;27(3):744-52.
8. Enquist IB, Lo Bianco C, Ooka A, Nilsson E, Månsson JE, Ehinger M, Richter J, Brady RO, Kirik D, Karlsson S (2007) "Murine models of acute neuronopathic Gaucher disease." , Proc Natl Acad Sci U S A. 2007 Oct 30;104(44):17483-8.

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Collaborators:

• Christopher Baum and colleagues, Hannover Medical School, Germany
• Tony Futerman, Weizmann Institute of Science, Israel
• Timothy Cox, University of Cambridg e, UK

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