2786 - Radiobiological Mechanism and Quantification of Low-Dose Radiation Therapy (LDRT) for Osteoarthritis Pains
Presenter(s)
S. Li; Department of Radiation Oncology, Fox Chase Cancer Center at Temple University Hospital, Philadelphia, PA
Purpose/Objective(s): To answer the question of how LDRT affected AO, we have explored the radiobiological responses by remodeling B, T, and other type LCs accumulated at the inflammation sites and BMSC migrating to OA sites for regenerating the injured bones and cartilages.
Materials/Methods: Thirty cell survival curves (CSCs) of human BMSCs and twenty-six CSCs of human LCs from 9 literatures were extracted and remodeled using a unified-multi-activation (UMA) model for accurately representing cell response to the typical treatment scheme of low dose of 0.5 Gy per fraction for total 6 every other day fractions. Effects of radiation types such as X-ray, protons, carbon ions, use of radiosensitizers such as Cisplatin, wortmannin and caffeine for BMSC, nonproliferating (unstimulated) and proliferation (CD3/CD28-stimulated) T, B and other LCs with activation of various caspase pathways and changes of cell distributions though the cell cycle or phases were all considered in the assessment of radiosensitivity.
Results: We found (1) All BMSC survival curves were single-population modeled with resulting survival rates from 0.1 to 0.6 after 0.5-Gy x 6 LDRT and use of radiosensitizers or charged particles further reduced survival rates and (2) most LC survival curves were modeled with combination of a radio-sensitive and a less radiosensitive population and the radiosensitive population increase with post irradiation time from 4 to 72 hr. Thus, every other day of twice per week treatment was desired to reduce lymphocytes to a fraction of 0.2 to 0.5 for T and B LC but not effectively for stimulated or radio-resistant LCs
Conclusion: Our remodeling of human BMSCs and LCs explained that 0.5Gy x 6 LDRT could effectively control the bone/cartilage growth and reduce overpopulated blood lymphocytes with acute responses for pain release. Secondary effects such as reducing adhesiveness of LC may also play a role in helping the local blood and LC circulation.