Ph.D. Projects
Hematopoietic stem cell gene therapy for lysosomal storage disorders
We are developing a gene therapy strategy based on transplantation of gene corrected hematopoietic stem cells (HSC) and on the use of advanced generation Lentiviral Vectors (LV) for the treatment of different lysosomal storage disorders (LSD) with nervous system (NS) involvement. Different projects are currently available focused on different LSD:
- HSC gene therapy for Metachromatic Leukodystrophy: potential for correction of the neuropathology. Metachromatic Leukodystrophy (MLD) is due to the deficiency of arylsulfatase A (ARSA) activity. It primarily affects the NS with severe and progressive dysmyelination. The clinical presentation is extremely variable; the infantile variant is the most frequent and the one with the worse prognosis. We demonstrated that transplantation of LV-transduced HSC allowed prevention and correction of the functional and neuropathological manifestations in the mouse model, when applied at early pre-symptomatic or already symptomatic stages, respectively, with a significantly higher therapeutic impact than allogenic HCT. Based on these data, a clinical trial of autologous HSC gene therapy will start during the second half of 2009 for the treatment of MLD patients. An experimental framework to interpret data obtained in the clinical trial will be generated, addressing relevant issues such as the therapeutic potential of patient’s gene corrected cells to cure CNS disease manifestations. Further, we are working on the mechanism of microglia (CNS resident macrophages) replacement by HSC-derived cells, with the final aims of unraveling i) the role of the conditioning regimen applied prior to the transplant in favoring microglia turnover, ii) the real nature of microglia precursors in the transplantation setting.
- New biomarkers of neuropathology in lysosomal storage disorders. In the prospective of selecting patients amenable to gene therapy (see above, first project), more information on the natural history and on the progression of MLD is needed. To increase our knowledge on the disease, we enrolled 30 MLD patients in a natural history study, which allowed us demonstrating the existence of a genotype-phenotype correlation, which could be used to provide prognostic indications. Moreover, we analyzed the transcriptome of our MLD patients’ blood cells to identify biomarkers to be used for monitoring disease progression and to unravel the contribution of other genetic or epigenetic factors to the patients’ phenotype. We identified a set of genes differentially expressed at a significant level, which could be used to correctly classify patients, with very high specificity and sensitivity. Among this set, a class of genes involved in protection from neural damage was significantly over-expressed in MLD patients’ blood cells and brain samples as compared to matched controls. The in depth characterization of this over-expression in MLD patients and mice during disease progression, and in samples from patients and animal models of other LSD will allow understanding whether these molecules could be used as disease biomarkers. Further, the observation of differential expression of these proteins in MLD patients opens interesting hints, which will be deepened within this PhD project, on the role that this family of proteins could exert in the pathological setting of a neurodegenerative disorder.
- Gene therapy for the treatment of Type I Mucopolysaccharidosis. Type I Mucopolysaccharidosis (MPSI) is due to the deficiency of iduronate sulfatase (IDUA), and is characterized by progressive accumulation of mucopolysaccharides in different tissues. Two main clinical variants exist, which differ for the presence of neurological impairment. The forms characterized by CNS involvement (Hurler syndrome) are not treated by ERT and respond poorly to HCT. The main goal of the project is the identification of a gene therapy strategy capable of efficiently deliver functional IDUA to the affected tissues of MPS I mice, and of alleviating systemic and neurological disease manifestations in the absence of immune responses. Particular attention will be dedicated to protein delivery across the blood brain barrier and to the identification of critical factors affecting the delivery (disease, age, conditioning regimen). To this goal we will compare two protocols based on LV: i) the HSC gene therapy approach, ii) a liver directed gene therapy approach exploiting the miRNA technology to escape immune responses.
