Xenotransplantation of primary human MDS stem cells into currently available immunodeficient mice, such as NOD-scid Il2rg−/− (NSG), has demonstrated limited success with low efficiency and transient engraftment, skewing towards the lymphoid lineage, and engraftment mostly restricted to the injected tibial bone when aided by co-injection of human mesenchymal stem cells (MSCs)7–10. This evidence concerns the gene IL2RG and myelodysplastic syndrome.