Figure 3. MYXV eliminates human MM cells while sparing normal primary human hematopoietic stem cells.

(A) U266 cells were mixed at a 10:1 ratio with donor human bone marrow derived CD34⁺ HSPCs. Mixtures were then mock-treated or infected with vMyx-GFP at MOI=10 for 24 hours and expression of GFP was analyzed using flow cytometry. Events shown are gated on live HLA-A2.1⁺ (Top) or CD34⁺ (Bottom) cells. Inset number indicates the percent of GFP⁻ and GFP⁺ cells. (B) U266 cells were mixed at a 10:1 ratio with purified human bone marrow derived CD34⁺ HSPCs. Mixtures were then mock-treated or infected with vMyx-GFP at MOI=10 and injected IV into NSG mice. Six weeks after injection, bone marrow was harvested from each mouse, stained with antibodies against human HLA-A,B,C, human HLA-A2.1, and human CD45 and analyzed using flow cytometry. U266 cells were identified as staining HLA-A,B,C⁺/HLA-A2.1⁺/CD45⁻ while progeny derived from normal HSPCs were identified as staining HLA-A,B,C⁺/HLA-A2.1⁻/CD45⁺. Data is presented as ‘level of engraftment’ which corresponds to the percent of HLA-A,B,C⁺/HLA-A2.1⁺ or HLA-A,B,C⁺/CD45⁺ cells in the bone marrow of each mouse. Mice displaying any level of positive cells were scored as engrafted (●) while mice without any detectable positive cells were scored as non-engrafted (○).