BM-HPCs efficiently generate colonies in vitro in response to a broad spectrum of growth factors and have CFU-S activity.

(A) Colony formation in vitro in the indicated factor/factor combinations of the BM-HPC line generated in SF/IL-6 (no. 5) and the BM-HPC line generated in SF (no. 9). Cloning efficiency is measured as the total number of colonies generated in the different factor/factor combinations compared with the total number of colonies generated in SF/Mix (SF/Tpo/IL-3/IL-6/GM-CSF/G-CSF/M-CSF/Epo), which is arbitrarily set as 100%. Spleen of a lethally irradiated B6-SJL control mouse (B) and a spleen of a mouse transplanted with BM-HPCs (C) 10 days after transplantation and fixed in Bouin solution. Original magnification B-C, × 9.6.