FOAMYCGD · Development of Foamy Virus Vectors for Gene Replacement in Chronic Granulomatous Disease
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2006-01-01 → 2007-12-31
- EU contribution
- €80,000
- Participants
- 1
- Scheme
- IRG
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Results in brief
Final Activity Report Summary - FOAMYCGD (Development of Foamy Virus Vectors for Gene Replacement in Chronic Granulomatous Disease)
Genetic disorders that affect the ability of an organism to fight infections from common pathogens result in life-long hospital admissions, impaired quality of life and a shortened survival. One such disorder is chronic granulomatous disease (CGD) that is caused by a single gene disorder which results in dysfunctional white blood cells. The disease can only be treated by transplantation of normal haematopoietic stem cells (HSC) but only about 25 % of the patients can find suitable donors. For the rest, a possible therapeutic strategy would be the correction of their own cells with a vector that carries the correct copy of the missing gene. This gene therapy approach has been successfully applied to a number of patients with other immunodeficiencies and it was the aim of our lab to develop vectors that can deliver genes to HSC. For gene transfer vehicles we used a retroviral vector based on the non-pathogenic virus called FoamyVirus (FV). The virus has the ability for permanent integration in the DNA of HSC and it prefers to integrate in areas of the genome that our away from known genes. Overall this vector system has the following features: 1) it is non-pathogenic to humans, 2) is incapable for replication, 3) it is documented that it can transfer genes to HSC of mouse and human origin and 4) it has a relatively safe integration profile. Our research strategy was to generate FV vectors with a correct copy of the gene and assay their performance in the model cell line and in the preclinical mouse model. After testing two FV vectors we constructed that displayed low levels of protein expression, we synthesized a vector that was optimized to work in mammalian cells. In the model cell line that we use, this vector showed levels of expression that were 88 % of the normal human cells with a correct copy of the missing gene. Such levels would be compatible with a clinical benefit in treated patients. In addition, the corrected cells expressed the protein stably over two months of continuous culture in vitro indicating that the vector was stable and the presence of the vector was not cytopathic to the cells. We then tested our vector in HSC from a mouse model where preliminary ex vivo data showed the animals who received corrected HSC to have successfully engrafted indicating that the ex vivo genetic manipulations did not affect the HSC's ability to home to a host. The phenotypic correction of the CGD disorder in the animal model will be assayed after an extended observation period of 6-12 months in order to confirm the safety of our approach prior to embarking for a human clinical trial.
Data: CORDIS, © European Union
Project objective
The current proposal is designed to test whether a retroviral vector developed from the Foamy virus (FV) can be used as a therapeutic vehicle to correct a human genetic disorder that affects the cells of the haematopoietic system. FV vectors are developed from the non-pathogenic foamy retrovirus and have been shown to transduce haematopoietic stem cells (HSC) of both murine and human origin. FV-based vectors show promise for therapeutic gene delivery into HSC and offer an alternative technology to the existing retro and lenti vector systems. As a next step in FV vector development, we plan the genetic correction of Chronic Granulomatous Disease (CGD), a disorder that results from the absence of NADPH-oxidase in the phagocytes of the peripheral blood and impaired killing of ingested microorganisms. Affected patients present with severe bacterial and fungal infections, which appear early on in life and may be fatal.The commonest form of CGD is X-linked and results from the absence of the gp91phox subunit of NA DPH. The relative knockout mouse model (X-CGD) closely mimics the human disease phenotype and will be used in this study. Preliminary studies with the X-CGD mouse model will aim at optimising transduction conditions for HSC gene transfer using reporter genes driven by constitutive and tissue-specific promoters. Following these studies, we will use the optimised conditions to transfer the therapeutic gene into the HSC of the X-CGD animals and will assay disease correction by standard assays. Finally, we will target CD34+ cells from individuals with CGD and evidence for disease correction will be obtained from both in vitro assays and after BMT into NOD/SCID mice. The experiments as described will provide us with the necessary data in a pre-clinical model of a human disease for which bone marrow transplantation is the only treatment option. The information obtained will be used for the rational design of a human gene therapy trial for affected patients.
Original text from CORDIS.
Participants
- INSTITUTE FOR BIOMEDICAL RESEARCH OF THE ACADEMY OF ATHENS · ATHENSCoordinatorCity levelGreece
Links
Data: CORDIS, © European Union