Abstract
BackgroundRadiotherapy used in tumor treatment compromises vascularization of bone tissue. Hyperbaric oxygenation (HBO) increases oxygen availability and improves vascularization, minimizing the deleterious effects of ionizing radiation (IR). Therefore, the aim of this study was to evaluate HBO therapy effect on bone macroscopy, composition and biomechanical properties after IR damage.MethodsTwenty male Wistar rats weighing 300 ± 20 g (10 weeks of age) were submitted to IR (30 Gy) to the left leg, where the right leg was not irradiated. After 30 days, ten animals were submitted to HBO therapy, which was performed daily for 1 week at 250 kPa for 90-min sessions. All animals were euthanized 37 days after irradiation and the tibia were separated into four groups (n = 10): from animals without HBO - right tibia Non-irradiated (noIRnoHBO) and left tibia Irradiated (IRnoHBO); and from animals with HBO - right tibiae Non-irradiated (noIRHBO) and left tibia Irradiated (IRHBO). The length (proximal-distal) and thickness (anteroposterior and mediolateral) of the tibiae were measured. Biomechanical analysis evaluated flexural strength and stiffness. Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) was used to calculate the amide I ratio, crystallinity index, and matrix to mineral ratios.ResultsIn the macroscopic and ATR-FTIR analysis, the IRnoHBO showed lower values of length, thickness and amide I ratio, crystallinity index and matrix to mineral ratios compared to noIRnoHBO (p < 0.03). IRnoHBO showed no statistical difference compared to IRHBO for these analyses (p > 0.05). Biomechanics analysis showed that the IRnoHBO group had lower values of flexural strength and stiffness compared to noIRnoHBO and IRHBO groups (p < 0.04). In addition, the noIRHBO group showed higher value of flexural strength when compared to noIRnoHBO and IRHBO groups (p < 0.02).ConclusionsThe present study concluded that IR arrests bone development, decreases the collagen maturation and mineral deposition process, thus reducing the flexural strength and stiffness bone mechanical parameters. Moreover, HBO therapy minimizes deleterious effects of irradiation on flexural strength and the bone stiffness analysis.
Highlights
Ionizing radiation (IR) used in radiotherapy treatment of patients with neoplastic lesions [1] induces hypovascularity, hypoxia and reduction of bone cells, impairing bone regenerative and remodelling [2, 3]
The present study concluded that ionizing radiation (IR) arrests bone development, decreases the collagen maturation and mineral deposition process, reducing the flexural strength and stiffness bone mechanical parameters
The present study showed that IR compromises bone growth, decreases mature/immature crosslinks ratio, changes morphology of HA crystals and collagen/HA ratio, decreasing flexural strength and stiffness in rat tibiae
Summary
Ionizing radiation (IR) used in radiotherapy treatment of patients with neoplastic lesions [1] induces hypovascularity, hypoxia and reduction of bone cells, impairing bone regenerative and remodelling [2, 3]. Hyperbaric oxygen (HBO) therapy, performed in a chamber with 100% oxygen at a pressure between 200 and 250 kilopascal (kPa), may be used to treat bone damage by irradiation to improve bone metabolism. Study performed in diabetic animals showed that HBO therapy may contribute to incorporation mineral crystals into collagen crosslinks, increasing the maximum fracture strength [9]. The effects of HBO therapy on bone matrix properties, compromised by irradiation, still remains unknown. Hyperbaric oxygenation (HBO) increases oxygen availability and improves vascularization, minimizing the deleterious effects of ionizing radiation (IR). The aim of this study was to evaluate HBO therapy effect on bone macroscopy, composition and biomechanical properties after IR damage
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