Session Item

The use of low-dose radiation therapy (LDRT) for osteoarthritis (OA) are rarely implemented except some European regions. There is a controversy over its clinical effects whereas little is known about how LDRT affects the actual disease progression. 

Using primary cultured human chondrocytes and synovium-derived cells from OA patients, the effects of LDRT were measured by cell viability assay, quantitative real-time PCR, western blotting, and RNA sequencing. For in vivo validation, a surgically induced OA model was used.

In vitro experiments indicated that LDRT have no significant impact on cell death, but slightly decreased expressions of pro-inflammatory factors including MMP13, without change in chondrogenesis markers. LDRT induces large transcriptomic changes in these cells, especially in mitochondrial activities. Growth differentiation factor 15 (GDF15) which is a mitohormetic signaling factor increased after LDRT and seemed to mediate anti-inflammatory effects of LDRT. We next found that rats treated with LDRT after anterior cruciate ligament transection or surgical destabilization of the medial meniscus exhibited decreased severity of OA compared to no-irradiation group at 10 weeks after surgery (mean OARSI score 3.7 in 0 Gy, 2.8 in 0.5 Gy, and 1.8 in 1 Gy, p = 0.003). The osteoclast activity also appeared to be significantly reduced in the LDRT group.

Taken together, LDRT could mitigate osteoarthritis progression by exerting its anti-inflammatory effects through modulating mitochondrial function.