Year 1

Our overall goal is to file an IND within 4 years for a hematopoietic stem cell based genetic therapy for HIV-1 disease. The concept is that introducing anti-HIV gene therapeutics into hematopoietic stem cells will produce a protected population of T lymphocytes and monocyte/macrophages (the cells specifically infected by HIV) in individuals to decrease viral load and maintain stable T lymphocyte counts. Hemapoietic stem cells are unique in that they are multipotent stem cells that give rise to all the types of blood cells, including T cells and monocytes/macrophages. During the first year we have met each of our key milestones and made significant progress in identifying and testing genetic reagents combined in the context of a lentiviral vector for stable delivery into hematopoietic stem cells. The vector candidates include combinations of gene therapeutics aimed at different stages of HIV replication namely: i) binding to the CCR5 HIV co-receptor (RNA interference to down-regulate CCR5), ii) fusion of the HIV virion to the cell surface (fusion inhibitor), iii) a restriction factor inhibiting translocation of the HIV genomic material from the cell surface to the nucleus (restriction factor) and, iv) inhibition of HIV expression within the cell (RNA interference directed to a key portion of HIV that drives its expression). We are presently identifying the optimal combination and vector/target ratio. We have also tested several reagents designed to increase transduction efficiency of hematopoietic stem cells and have validated assays to examine potential toxicity including genotoxicity of therapeutic vectors. Thus far, we have not seen any general vector-induced toxicity. In order for this gene transfer to be applied to patients, the hemapoietic progenitor stem cell transduction must be scaled up significantly. Experiments are currently in progress maximizing transduction of hemapoietic progenitor stem cells at sufficiently high cell numbers for future therapeutic analysis.