The Radiosensitivity of the Bone-forming Process of Heterotopically-grafted Rat Bone-marrow

Summary

Haemopoietic tissue when grafted to a heterotopic site has bone-forming potential. The incidence of bone formation by subcutaneously-placed rat marrow was plotted as a function of the number of cells in the transplant. 48 × 10⁶ nucleated marrow cells were then exposed in vitro to varying doses of x-radiation, transplanted subcutaneously, and the incidence of bone formation observed. By using the original curve, it was then possible to determine the fraction of cells surviving radiation. A dose–survival curve was constructed which was exponential, and from the linear part a D₀ of 235 rads with an extrapolation number of 1·2 was calculated. The significance of the relative radioresistance of the bone-forming process when compared to the radiosensitivity of the haemopoietic function of bone-marrow was discussed.