FGFR3-TD targets an early B-cell progenitor.

Serial analysis of FGFR3-TD–expressing BM cultured in vitro revealed an excess of pre-B cells by week 7 (A) and an excess of early B-cell colonies by week 4 to 5 (B) when compared to FGFR3-WT and MINV vector only controls. ○, TD; ▪, WT; ▵, MINV. (C) A single plucked colony from an FGFR3-TD–transduced BM culture differentiated into a predominantly B-cell population after 3 months in culture. (D) Circulating pre-B cells were increased in the blood of mice receiving transplants as early as 2 weeks after transplantation. ■, MINV; ░, WT; ▪, TD.