Hematopoietic Stem Cell-Derived Chimeric Antigen Receptor Expressing Cells Traffic to HIV Reservoir Sites in SHIV-Infected Non-Human Primates

Thesis (Master's)--University of Washington, 2019The successful treatment of 2 HIV+ individuals with allogeneic stem cell transplantations has garnered much interest in its utility as a therapy for HIV. However, there are significant limitations that prevent allogeneic stem cell transplantation from being a viable therapy for HIV infection, including toxicity due to Graft-versus-host disease, and the limited availability of donors who are homozygous for the CCR5Δ32 mutation. One viable option to circumvent these limitations and provide a functional cure, through immune-mediated elimination of the virus, is with chimeric antigen receptor (CAR) immunotherapy. By introducing the CAR engineered to target HIV infected cells into hematopoietic stem cells, we have the potential to generate a self-renewing population of CAR T-cells, thus circumventing some of the limitations with longevity that are seen with CAR T-cells. Here, we report trafficking of hematopoietic stem and progenitor (HSPC)-derived CAR+ cells to HIV tissue reservoir sites, in a pigtail macaque model of HIV infection. CAR+ cells were identified in the lymphoid germinal centers, the parenchyma of the central nervous system, and the gastrointestinal tract by immunohistochemistry, almost 2 years after initial engraftment with lentiviral modified HSPCs. Multilineage engraftment of CAR+ cells were identified in lymphoid germinal centers and the gastrointestinal tract, consisting of T-cells, B-cells, and myeloid lineage cells. CAR+ B-cells in the germinal centers were also actively replicating, characterized by robust Ki-67 expression. No difference was observed in trafficking, engraftment, and cell cycle activity between CAR animals and control animals that carry a “tailless” CAR which lacks the cytoplasmic signal transduction domain. These results show the HSPC-derived CAR+ cells will traffic to, and persist in, HIV tissue reservoir sites, with multilineage engraftment of CAR+ cells. The method could be used as a platform for immunotherapeutic delivery treatment of HIV infection, as well as a variety of other medical conditions