This project is directed at developing approaches to effect a "cure" for HIV infection. Human CD 34+ hematopoietic stem cells will be mutated to lack the CCR5 major binding site for HIV, and the derived immune cells will resist HIV infection. This strategy will permit the repopulation of an HIV-infected individual with HIV- resistant immune cells and would bring about long-term survival without the need for antiretroviral drugs.
The objective of this proposal is to develop an effective method for providing a "functional cure" for HIV- infected individuals. The approach is based on the observation that subjects lacking CCR5 expression can be highly resistant to HIV infection. Our hypothesis is that hematopoietic CD34+ stem and progenitor cells (HSPC) can be made resistant to HIV infection via mutation in the CCR5 gene. These cells transplanted back to autologous donors will prevent HIV replication and effect a "cure." First, purified human CD34+ cells or peripheral blood mononuclear cells from uninfected individuals will be converted into induced pluripotent stem (iPS) cells by strategies that emphasize non-integrating vectors. These iPS cells will then be genetically modified to have the ?32bp natural mutation of CCR5 associated with the absence of this receptor expression on the cell surface. Notably, cells naturally lacking CCR5 expression were given to the "Berlin patient" who has no evidence of HIV infection after several years. The iPS-derived CCR5-mutated cells will be converted into CD34+ cells (i.e. iPS-derived CD34+ HSPC) and then differentiated into hematopoietic progeny cells. These cells will be evaluated for resistance to HIV infection and normal cell function in cell culture and after transplantation into humanized mice. The same procedures will be undertaken with genetically modified CD34+ cells from HIV-infected individuals. These studies are directed at optimizing our approaches for providing iPS- derived CD34+ HSPC to HIV- infected individuals to prevent HIV disease progression and potentially establish a "functional cure."