“…The first successful report of engraftment of hu-AML into SCID recipients was reported in 1991 (De Lord et al, 1991). Because of innate host resistance and lacking species cross reactivity in cytokines, consequent studies (De Lord et al, 1991;Cesano et al, 1992;Ratajczak et al, 1992;Namikawa et al, 1993;Cesano et al, 1994;Chelstrom et al, 1994;Lapidot et al, 1994;Pirruccello et al, 1994;Yan et al, 1996) were eclipsed by major practical and limiting considerations. While giving exogenous human growth factors, including interleukin 3 (IL-3) (Goan et al, 1995;Cashman et al, 1997), IL-6 (Goan et al, 1995), granulocyte-macrophage-colony stimulating factor (GM-CSF) (Goan et al, 1995;Cashman et al, 1997), a fusion protein of IL-3 and GM-CSF (PIXY321) (Lapidot et al, 1992;Lapidot et al, 1994), steel factor (SF) (Cashman et al, 1997), mast-cell growth factor (hMGF) (Lapidot et al, 1994) and erythropoietin (EPO) (Cashman et al, 1997) to these recipients, resulted in enhanced engraftment and differentiation of human cells in SCID recipients.…”