Fluorescently labeled Myc-induced T-ALLs from CG1-strain zebrafish engraft into nonirradiated CG1-strain recipients. (a)–(c) GFP-labeled T-ALLs were isolated from primary leukemic fish, and 1 × 10³ FACS sorted GFP-labeled leukemia cells were transplanted into nonirradiated CG1-strain animals and scored for engraftment at 10, 20, and 30 days posttransplantation. (d)–(f) T-ALL transplant recipients that express Amcyan (d), dsRED (e), and zsYellow (f) under the rag2 promoter. Panels are merged images of fluorescent and brightfield photographs. Images were originally published in [23].

Zebrafish T-lymphoblasts overexpressing bcl2 spread locally but fail to intravasate into vasculature. (a)–(c) dsRED2-expressing lymphoma cells (b) from the Myc; Cre fish intravasate into EGFP-labeled vasculature (a) of the transplant host Tg(fli1:EGFP); Casper by 6 days posttransplantation (see arrowheads in (c)). (d)–(f) In contrast, dsRED2-expressing lymphoma cells (e) from the Myc; Cre; bcl2 fish fail to intravasate vasculature (d) of the transplant hosts by 6 days posttransplantation (compare (f) with (c)). Note aggregates of the Myc; Cre; bcl2 lymphoma cells in (e) and (f). Scale bar is 10 μm. Reprinted from [10].

Syngeneic zebrafish transplant models of T-ALL are a powerful tool for drug discovery: T-ALL growth is suppressed by cyclophosphamide treatment. Approximately 200 cells/5 nL were engrafted into 5-day-old syngeneic CG2 
larvae. Engrafted animals were treated with cyclophosphamide (400 mg/L dissolved in fish water) beginning 5 days posttransplantation. Images of control (a) and treated animals. (b) Tumor growth was assessed based on the percentage of body taken over by GFP+ T-ALL and compared using  t-test calculations. This work was performed in [31] and later published in [61].