1. ¹Institut National de la Santé et de la Recherche (INSERM), U768, Université Paris Descartes, Hôpital Necker-Enfants Malades, Paris,France
2. ²Généthon, Evry, France
3. ³Unité de Développement des Lymphocytes, Département d'Immunologie, INSERM, U668, Institut Pasteur, Paris, France
4. ⁴Service d'Histologie-Embryologie et Cytogénétique Assistance Publique, Hôpitaux de Paris (AP/HP), Hôpital Necker-Enfants Malades, Paris, France
5. ⁵Service d'Anatomie et Cytologie Pathologique, AP/HP, Hôpital Necker-Enfants Malades, Paris, France
6. ⁶Cellectis SA, Romainville, France
7. ⁷Département de Virologie Moléculaire et Vectorologie, INSERM, U668, Institut Pasteur, Paris, France
8. ⁸Unité d'Immunologie et Hématologie Pédiatrique, AP/HP, Hôpital Necker-Enfants Malades, Paris, France
9. ⁹Service d'Hématologie, AP/HP, Hôpital Necker-Enfants Malades, Paris, France
10. ¹⁰Département de Biotherapie, AP/HP, Hôpital Necker-Enfants Malades, Paris, France

Correspondence: Marina Cavazzana-Calvo, Département de Biothèrapie, Hôpital Necker-Enfants Malades, 149 rue de sévres, 75015 Paris, France. E-mail: m.cavazzana@nck.aphp.fr

Received 20 February 2008; Accepted 30 April 2008; Published online 17 June 2008.

Abstract

Patients with mutations in the Artemis gene display a complete absence of T- and B lymphocytes, together with increased cellular radiosensitivity; this leads to a radiosensitive severe combined immunodeficiency (RS-SCID). Allogenic hematopoietic stem-cell (HSC) transplantation is only partially successful in the absence of an human leukocyte antigen–genoidentical donor, and this has prompted a search for alternative therapeutic approaches such as gene therapy. In this study, a self-inactivated lentiviral vector expressing Artemis was used to complement the Artemis knockout mouse (Art^-/-). Transplantation of Artemis-transduced HSCs into irradiated Art^-/- mice restored a stable (over a 15-month period of follow-up) and functional T- and cell repertoire that was comparable to that of control mice. The success of secondary transplantations demonstrated that the HSCs had been transduced. One of thirteen mice developed a thymoma 6 months after gene therapy. Although thymic cells were seen to be carrying two lentiviral integration sites, there was no evidence of lentivirus-driven oncogene activation. The Art^-/- mice were found to be prone to develop T-cell lymphomas, either spontaneously or after irradiation. These data indicate that the observed lymphoproliferation was probably the consequence of the chromosomal instability associated with the Artemis-deficient background. As a whole, our work provides a basis for supporting the gene therapy approach in Artemis-deficient SCID.