IN VIVO targeted transfection of IL-3 gene into murine haematopoietic progenitor cells through CD117

A. Chapel1, M. Bensidhoum1, C. Germain1, P. Poncet2, C. Goupy3, G. Chavanel3, F. Hirsch3, D. Thierry1

1 Département de Protection de la santé de l'Homme et de Dosimétrie, Section Autonome de Radiobiologie Appliquée à la Médecine, IPSN, Fontenay-aux-Roses, France, 2 Institut Pasteur, Unité d'Immuno-Allergie, Paris, France, 3 Equipe d'Immunologie Cellulaire et de Transplantation, CNRS, Villejuif, France.

AIM We studied the ability to target exogenous gene expression into a subset of immature haematopoietic CD117+ cells (c-kit expressing cells). METHODS In vivo haematopoietic cell targeting using cell specific receptor-mediated endocytosis was performed by the mean of a monoclonal anti-CD117 chemically coupled to human IL-3 gene-containing plasmid DNA. Human IL-3 gene product might be processed as murine IL-3 protein in transfected cells without consumption by murine haematopoietic cells making its detection easier. Mice were intravenously injected twice and euthanasied 5, 7 or 10 days after the first injection of the conjugate. In order to detect human IL-3 produced at low level by CD117+ transfected cells, long term bone marrow cultures were performed. RESULTS IL-3 transgene presence and expression was specifically detected in bone marrow of transfected mice up to 10 days. PCR analysis of other tissues evidenced the specific targeting since brain, liver and kidney were negative. No human IL-3 protein was detected in peripheral blood or in cell culture supernatant of long-term bone marrow culture in transfected mice. These results account for a locally targeted transient expression of growth factor transgene specifically in bone marrow. CONCLUSION These data suggest that transfection using anti-c-kit antibody covalently coupled to a growth factor gene allows IL-3 gene expression targeting into haematopoietic progenitor in vivo.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Gene Therapy, Part 2.

This presentation received an honorable mention in our poster contest and was recognized with the Symposium Presidents' Award for Scientific Excellence.