Radiosensitivity of stromal cells responsible for in vitro maintenance of hemopoietic stem cells in continuous, long-term marrow culture.

Marrow stromal cells are generally thought to be radioresistant. However, when the marrow was irradiated in vivo or in vitro before its use for the continuous long-term marrow culture, doses of radiation as low as 500 rad interfered with the establishment of the adherent stromal layer. Moreover, when the stromal layer was permitted to establish, similar doses of radiation interfered with its potential to support the proliferation and maintenance of the hemopoietic stem cell. Thus, marrow stromal cells appear to be more radiosensitive than hitherto thought. The type of damage may vary, however, according to the dose of radiation. Small doses may interfere with such functions as adhesion or cell division while larger doses may completely destroy the cell.