“… 18 , 83 To overcome these, microenvironmental alterations to favor human hematopoiesis have been described (Figure 2 ). Methods include (1) mutation of critical murine growth factor receptors, such as the c-kit receptor (NSGW41, NSGWv/+, NSGWv, NBSGW, SRG-W41, and BRgWv mice), 23 , 30 (2) inhibition of growth factor receptor function (eg, anti-c-kit receptor antibody), 84 (3) exogenous human cytokine administration (eg, B lymphocyte stimulator for mature human B cell reconstitution 63 and IL-7 analogues for T cell reconstitution 75 ), and (4) knock-in of human cytokine genes, such as in SGM3, 27 MISTRG, 42 SRG-15, 85 and hIL-6 Tg NSG 28 strains, which include knock-ins of IL-3, IL-15, GM-CSF, M-CSF, or IL-6 to support engraftment of the wider human hematopoietic repertoire, including innate cells and regulatory T cells (Treg). 27 …”