SUMMARY
Evaluation of the therapeutic potential of RNAi for HIV infection has been hampered by the challenges of siRNA delivery and lack of suitable animal models. Using a novel delivery method in humanized mice, we show that siRNA treatment can dramatically suppress HIV infection. A CD7-specific single-chain antibody was conjugated to oligo-9-arginine peptide (scFvCD7-9R) for T cell-specific siRNA delivery in NOD/SCIDIL2rγ−/− mice reconstituted with human lymphocytes (Hu-PBL) or CD34+ hematopoietic stem cells (Hu-HSC). In HIV-infected Hu-PBL mice, treatment with anti-CCR5 and antiviral siRNAs complexed to scFvCD7-9R controlled viral replication and prevented the disease-associated CD4 T cell loss. This treatment also suppressed endogenous virus and restored CD4 T cell counts in mice reconstituted with HIV+ PBMC. Moreover, scFvCD7-9R could deliver antiviral siRNAs to naïve T cells in Hu-HSC mice and effectively suppress viremia in infected mice. Thus, siRNA therapy for HIV infection appears to be feasible in a preclinical animal model.
SummaryImmunodeficient non-obese diabetic (NOD)-severe combined immunedeficient (scid) mice bearing a targeted mutation in the gene encoding the interleukin (IL)-2 receptor gamma chain gene (IL2rg null ) engraft readily with human peripheral blood mononuclear cells (PBMC). Here, we report a robust model of xenogeneic graft-versus-host-like disease (GVHD) based on intravenous injection of human PBMC into 2 Gy conditioned NOD-scid IL2rg null mice. These mice develop xenogeneic GVHD consistently (100%) following injection of as few as 5 ¥ 10 6 PBMC, regardless of the PBMC donor used. As in human disease, the development of xenogeneic GVHD is highly dependent on expression of host major histocompatibility complex class I and class II molecules and is associated with severely depressed haematopoiesis. Interrupting the tumour necrosis factor-a signalling cascade with etanercept, a therapeutic drug in clinical trials for the treatment of human GVHD, delays the onset and progression of disease. This model now provides the opportunity to investigate in vivo mechanisms of xenogeneic GVHD as well as to assess the efficacy of therapeutic agents rapidly.
Abstract"Humanized" mice are a promising translational model for studying human hematopoiesis and immunity. Their utility has been enhanced by the development of new stocks of immunodeficient hosts, most notably mouse strains such as NOD-scid IL2rγ null mice that lack the IL-2 receptor common gamma chain. These stocks of mice lack adaptive immune function, display multiple defects in innate immunity, and support heightened levels of human hematolymphoid engraftment. Humanized mice can support studies in many areas of immunology, including autoimmunity, transplantation, infectious diseases, and cancer. These models are particularly valuable in experimentation where there is no appropriate small animal model of the human disease, as in the case of certain viral infections. This unit details the creation of humanized mice by engraftment of immunodeficient mice with hematopoietic stem cells or peripheral blood mononuclear cells, provides methods for evaluating engraftment, and discusses considerations for choosing the appropriate model system to meet specific goals.
SummaryImmunodeficient hosts engrafted with human lymphohaematopoietic cells hold great promise as a preclinical bridge for understanding human haematopoiesis and immunity. We now describe a new immunodeficient radioresistant non-obese diabetic mice (NOD) stock based on targeted mutations in the recombination activating gene-1 (Rag1 null ) and interleukin (IL)-2 receptor common gamma chain (IL2rg null ), and compare its ability to support lymphohaematopoietic cell engraftment with that achieved in radiosensitive NOD.CB17-Prkdc scid (NOD-Prkdc scid ) IL2rg null mice. We observed that immunodeficient NOD-Rag1 null IL2rg null mice tolerated much higher levels of irradiation conditioning than did NOD-Prkdc scid IL2rg null mice. High levels of human cord blood stem cell engraftment were observed in both stocks of irradiation-conditioned adult mice, leading to multi-lineage haematopoietic cell populations and a complete repertoire of human immune cells, including human T cells. Human peripheral blood mononuclear cells also engrafted at high levels in unconditioned adult mice of each stock. These data document that Rag1 null and scid stocks of immunodeficient NOD mice harbouring the IL2rg null mutation support similar levels of human lymphohaematopoietic cell engraftment. NOD-Rag1 null IL2rg null mice will be an important new model for human lymphohaematopoietic cell engraftment studies that require radioresistant hosts.
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