Gene transfer offers potential for the development of novel approaches to the treatment of multiple myeloma. Targets for gene transfer include the myeloma cells themselves using cytoreductive genes, the hematopoietic stem cells using chemoprotective or antiresorptive genes (e.g., osteoprotegerin), and T lymphocytes using genes coding for chimeric T cell receptors. Quiescence of the target cell population is an important consideration for all of the aforementioned approaches, and since lentiviruses can infect nondividing cells, they are attractive vectors for gene-based therapies in this disease. Specific transgene expression might be achieved either by targeting entry of the vector or by restricting its expression to the target cells of interest. We previously developed a retroviral vector targeting strategy named inverse targeting that provides for the selective transduction of hematopoietic cells in a mixed population (Fielding et al. Blood, Vol 91, 1802-1809, 1998). Here we have applied the inverse targeting strategy to lentiviral vectors and have explored the in vivo potential of the approach. Luciferase expressing lentiviral vectors were pseudotyped with wild-type or EOF displaying 4070A amphotropic envelope glycoproteins. Inverse targeting of the EGF displaying vectors was demonstrated by their ability to transduce EGF receptornegative cells, but not EGF receptor-positive cells. Infectivity on EGF receptor-positive cells was restored by addition of soluble EGF as competitor or by protease cleavage of the displayed EGF domain. High tiler stocks of the targeted vectors were generated using a novel calcium phosphate-based virus concentration strategy. The concentrated vectors were then infused intravenously into athymic mice and organs were harvested at intervals thereafter to determine the pattern of gene delivery and expression. Using vectors displaying the unmodified 4070A envelope, luciferase gene expression was detected predominantly in liver, spleen and heart. This pattern of gene expression was significantly altered in the case of the EGF-displaying lentivirus vector. The most striking observation being that expression in liver, which carries a high density of EGF receptors, was greatly reduced. Additional studies are currently underway to further investigate these findings.
|Original language||English (US)|
|Issue number||11 PART II|
|State||Published - Dec 1 2000|
ASJC Scopus subject areas
- Cell Biology