Direct evidence for a stem cell common to hematopoiesis and its in vitro microenvironment: studies on syngeneic (inbred) Wistar Furth rats.

When injected into a group of lethally irradiated syngeneic (inbred) Wistar Furth (WF) rats, suspensions of stromal cells grown in monolayer culture from the marrow of WF rats produced hemopoietic colonies in the spleen and rescued 50% of the rats, while 90% of the non-injected (control) rats died within 30 days and had no hemopoietic colonies in the spleens. Fifty percent of the injected (test) rats which died between days 6 and 22 showed hemopoietic regeneration in the bone marrow, while little or no evidence of hemopoietic regeneration was seen in the control animals. Our results suggest that the marrow stroma grown in vitro contain cells with hemopoietic potential and are transplantable.