Effects of liquid nitrogen treatment on the proliferation ofosteosarcoma and the biomechanical properties of normal bone

Abstract

To overcome problems of autografts for reconstructionin the presence of malignant bone and soft tissuetumors, we devised a method for treating autografts thatutilizes the hypothermic effect of liquid nitrogen. Wemeasured temperature changes inside the bone at eachcondition and established a one-cycle liquid nitrogen protocolthat included 20min in liquid nitrogen, 15min in room air, and15min in physiological saline. The proliferation potential ofthe tumor cells treated with the liquid nitrogen method wasexamined by means of bromodeoxyuridine (BrdU) immunostaining.Tumor proliferation potential in vivo was examined innude mice. Based on the results we concluded that the tumorcells died out as a result of the liquid nitrogen method. Regardingcompression strength there was no significant differencebetween intact bone and liquid nitrogen-treated bone,whereas the strength of the autoclaved bone was decreased.Scanning electron microscopic examination of the fracturesurface of the autoclaved bone after the compression testshowed an irregular, uneven surface, whereas that of theliquid nitrogen-treated bone was smooth and fine-grained.This might be one of the reasons for the discrepancy in compressionstrength.