Effects of ionizing radiation on proteins in lyophilized or frozen demineralized human bone

Abstract

ObjectiveThe aim was to study the effects of application of ionizing radiation (gamma and electrons) as sterilizing agents at doses of 15 kGy, 25 kGy and 50 kGy, on lyophilized or frozen demineralized bone tissue for use in transplants.MethodsFive human femoral diaphyses from different donors of musculoskeletal tissue were demineralized and preserved as lyophilized or frozen at −80 °C. The samples were divided into two groups: non-irradiated (control) and irradiated by means of gamma rays or an electron beam. The bone proteins were extracted and used to determine the concentrations of total protein and BMP 2 and 7.ResultsDecreases in total protein and BMP 2 and 7 concentrations were observed. The decreases in total protein concentrations, in comparison with the respective control groups, were significant in the lyophilized and frozen samples that were irradiated at a dose of 50 kGy of gamma radiation and electron beam, with reductions of more than 30%. Significant decreases in the levels of BMP 2 and 7 were also observed at higher doses and especially through use of the electron beam.ConclusionThe reductions in the concentrations of total proteins and osteoinductive proteins (BMP 2 and 7) were related to the radiation dose, i.e. they increased with higher doses of ionizing radiation type and the type of bone preservation. The largest reductions in concentrations were observed in the bones irradiated by means of an electron beam and at a dose of 50 kGy. However, this type of radiation and this high dose are not usual practices for sterilization of bone tissue.

Estudo comparativo da osteointegração de enxertos ósseos irradiados e não irradiados utilizados em pacientes com revisão de artroplastia do quadril

“…The tissues were irradiated with gamma rays at a dose of 25 kGy, with a dose rate of 0.00138 kGy/s and an approximate temperature of -70°C, since these conditions reduce undesirable radiation effects, including high doses, high energy transfer rate and heating respectively, in order to maintain their biological integrity. 4…”

“…However, homologous bone tissues have advantages when compared to autologous tissues, including reduced morbidity, lack of a second surgical incision, and lower blood loss during surgery; moreover, homologous tissues enable reconstructions requiring a greater amount of graft. 2 3 4…”

“…In orthopedics, bone grafts are used mainly in scoliosis surgeries, musculoskeletal tumor resection, pseudarthrosis treatment and revision hip and knee arthroplasty with increasing procedural numbers. 2 4 The improvement of tissue banks in the preparation and supply of different types of graft increased the efficiency of bone transplants and revision arthroplasty surgeries with severe bone stock loss. 5 6 7…”

“…There is a great concern in assuring the quality of bone tissues and the safety of the recipients regarding the transmission of infectious and contagious diseases. 4…”

“…Porém, os tecidos ósseos homólogos têm vantagens quando comparados aos autólogos, tais como a redução da morbidade, por evitar uma segunda incisão cirúrgica com menor perda sanguínea durante a cirurgia, além de possibilitar reconstruções que requerem maior quantidade de enxerto. 2 3 4…”